WK4DS Amateur Radio Blog

David Saylors 3/11/26 David Saylors 3/11/26

Ten watts to Spain. Ten watts to Germany. Ten watts to Austria. The EFHW at 35 feet made all the difference.

Activating Hillsborough River State Park (US-1878) with a friend is one thing—making over 100 contacts in a single afternoon using QRP power and a homemade wire antenna is another. That's exactly what Chas and I accomplished using a 65-foot EFHW antenna strung 35 feet up in the Florida pines, a ground mounted vertical, his FT891, a Penntek TR-35, and my sBitx v3 running just 10 watts (Chas was running 50 watts today though). This wasn't just a Parks on the Air activation—it was a field test of how well minimalist gear performs in a multi-operator setup, complete with lessons learned about antenna placement, front-end overload, and working around the Florida sun.

Activating Hillsborough River State Park (US-1878) with a friend is one thing, making over 100 contacts in a single afternoon using QRP power and a homemade wire antenna is another. That's exactly what Chas and I accomplished using a 65-foot EFHW antenna strung 35 feet up in the Florida pines, a ground mounted vertical, his FT891, a Penntek TR-35, and my sBitx v3 running just 10 watts (Chas was running 50 watts today though). This wasn't just a Parks on the Air activation, it was a field test of how well minimalist gear performs in a multi-operator setup, complete with lessons learned about antenna placement, front-end overload, and working around the Florida sun.

Hillsborough River State Park entrance designated K-1488 for Parks on the Air activations.

Hillsborough River State Park: Location and Access

Hillsborough River State Park sits about 12 miles north of Tampa and makes for an excellent POTA location. When you arrive at the entrance, the first thing you're greeted with is a ranger station where you pay your four dollar entrance fee. Yes, you read that right—four dollars for the whole day. This is a really nice park with extensive hiking trails, a large loop perfect for biking, and the Hillsborough River running through it where visitors can enjoy boating and fishing.

There's plenty of infrastructure here for families… playgrounds, picnic areas with covered pavilions, and well-maintained facilities. For POTA activators, the key feature is the abundance of tall trees throughout the park, making it ideal for wire antennas. The main loop road has several pull-off areas with picnic tables that work perfectly as operating positions. Cell phone coverage is good throughout the park, which helps for spotting yourself on the POTA network and coordinating with other operators.

After paying the entrance fee, I drove around the loop a couple of times while talking to Chas on the phone, trying to figure out where he'd set up. Here's the kicker, though, he decided to drive over to my location so we could operate together from adjacent tables. This gave us the multi-operator experience but also taught us some valuable lessons about antenna placement and RF interference, which I'll get into later.

65-foot EFHW antenna deployment in tree at Hillsborough River State Park with yellow highlight showing wire position — The 65-foot EFHW antenna strung into the tree canopy (highlighted in yellow) getting the wire 35 feet high made a dramatic difference in propagation. The wire itself is nearly invisible against the tree background.

The Antenna Setup: 65-Foot EFHW in the Trees

Today saw the use of a 65-foot long wire antenna, an End-Fed Half-Wave from Reliance Antennas. This antenna isn't rated for high power, so I held all of my transmit power to 10 watts or less throughout the day to prevent potential damage to the matching transformer. We deployed it using throw lines to get it about 35 feet up into a large oak tree, then Chas loaned me his 10-foot push-up pole and stand to support the feed point end of the antenna and get it a little higher off the ground as well.

I believe this additional height aided propagation dramatically. Getting the whole 40-meter EFHW that high off the ground, with the far end even higher in the tree, made a noticeable difference compared to previous activations where I'd run antennas lower. I made many contacts all over the United States, into Mexico, and even worked some European stations on the higher bands with just 10 watts. That's the magic of getting a wire antenna up high… height matters more than power in many cases.

The EFHW is resonant on 40m, 20m, 15m, and 10m without needing an antenna tuner, which keeps the station setup simple. I specifically avoided the WARC bands (30m, 17m, 12m) during this activation because the antenna isn't cut for those frequencies and I didn't want to deploy a tuner. Sometimes keeping things simple is the better approach, especially when you're testing equipment and learning how gear performs in the field.

Hillsborough River State Park ranger station entrance building where visitors pay $4 entrance fee — The ranger station where you pay the $4 entrance fee to access the park for POTA activations.

Radio Gear: Penntek TR-35 and sBitx v3 Performance

Once I had the antenna set up and tested, I decided to use the Penntek TR-35 transceiver first. I really enjoy using this tiny little radio, the CW break-in is phenomenal, and the keying from the internal keyer circuit works flawlessly. It's a true QRP radio putting out 5 watts maximum, and I've made some additional accessories for it to turn it into a more complete field station. But even as it sits stock, it's a wonderful little radio that's almost impossible to damage from bad antennas or other field mishaps. Plus, it just works really well at making contacts.

I started on 40 meters and after working through a good run of stations, I decided to move up to 20 meters where activity was heating up. Chas started on 30 meters and worked his way through the WARC bands, eventually ending up on 10 meters where we made a park-to-park contact with each other from 30 feet apart. That was pretty funny, logging a P2P (park-to-park) contact when we could literally see each other across the operating area. I turned my output power all the way down, it showed literally zero output and I was still booming into Chas’ radio!!! Haha!

After finishing my run on 20 meters with the Penntek TR-35, I swapped it out for my sBitx v3. I throttled the output power on the sBitx for two reasons: first, to prevent damage to the antenna which isn't rated for high power, and second, to keep from running down my battery too quickly. I'd brought an 8 amp-hour LiFePO4 battery, and if I'd run the sBitx at full output power I could have easily depleted that battery in an hour or so, especially running FT8 on the lower bands which requires more transmit time. As it turned out, limiting power to 10 watts kept the battery happy all day and I still had plenty of capacity left when we packed up.

Penntek TR-35 QRP transceiver with Dell laptop, CW paddle key, and logbook on picnic table at POTA activation — Initial station setup with the Penntek TR-35, Dell laptop for logging, clipboard with paper log, and CW paddle ready to make contacts.

The first thing I did with the sBitx was get on 15 m and attempt to make contacts there on FT8. This went pretty well and I made several contacts on 15 m before moving to 10 m to see what I could make on that band. The reason I skipped the WARC bands today was because this antenna is not resonant on any bands other than 40, 20, 15, and 10 m. So I stayed on those bands as I did not want to try and deploy an antenna tuner as well.

The sBitx v3 with improvised sunshade, Florida sun glare was a constant challenge throughout the activation. Notice the notebook to keep my arm off that rough concrete!

Contact Statistics:

Between Chas and me, we logged 118 total QSOs during the activation! 66 in my log and 52 in Chas's log(I did operate a little longer than him and we were not in a race either). Here's my detailed breakdown:

David's Stats (WK4DS):

40 meters: 5 QSOs (all CW)
20 meters: 50 QSOs (all CW)
15 meters: 1 QSO (CW)
10 meters: 10 QSOs (8 FT8, 2 CW)

Total: 66 QSOs

CW: 58 contacts
FT8: 8 contacts

Geographic Breakdown:

Domestic (USA): 56 QSOs across the continental United States
DX (International): 10 QSOs reaching six countries:
- Spain: 2 contacts (EA4T, EA5BCO)
- Germany: 2 contacts (DL4JCP, DJ9HX)
- Mexico: 2 contacts (XE2BCS, XE2IF)
- Austria: 1 contact (OE2IGP)
- Canada: 1 contact (VE1ZZ)
- Poland: 1 contact (SQ9JS)
- Czech Republic: 1 contact (OL26WRTC - special event station)

Chas's Stats: Chas logged 52 QSOs throughout the day, primarily working 30m, 17m, and 10m (he might have done more but that is all I know of) while I focused on 40m, 20m, 15m & 10m. This band coordination helped us avoid stepping on each other while maximizing total contacts for the activation.

Combined Performance: For QRP power (my 10 watts maximum and Chas running 50 watts) and simple antennas, 118 total contacts in one afternoon represents excellent POTA performance. The 10 DX contacts on 10 meters with just 10 watts and the EFHW antenna particularly stand out, working Spain and Germany on FT8, then switching to CW for additional European contacts, demonstrates what's possible when propagation cooperates and you get your antenna up high.

Twenty meters was the workhorse band, delivering 50 contacts in my log alone. The concentration of activity on 20m CW (14.061 MHz) is typical for POTA activations, as this is where most hunters are listening for parks. The handful of 40m contacts at the start of the activation caught the tail end of daytime propagation before that band shifted to primarily short-skip domestic contacts.

Operating Challenges - Sun and Glare

Both Chas and I learned pretty quickly that the Florida sun was not our friend today, even though the temperature was pleasant. The glare from the sun continuously made us struggle to see our displays and adjust settings. I think Chas literally just toughed it out and lived with squinting at his screen. I, on the other hand, kept deploying improvised sunshades and repositioning my station to create shade for my equipment as the day wore on, as you can see in the photos. This is something to think about when planning a POTA activation, a simple popup canopy or umbrella can make the difference between comfortable operating and constantly fighting the sun. Add that to my growing list of field operation lessons learned.

sBitx v3 CW Keying: Improvements and Remaining Issues

The CW keying in the sBitx has been dramatically improved as the software revisions continue. The developers keep optimizing the scan time of the Raspberry Pi processor and how the program executes, making the keyer more responsive with each update. It's almost like using a regular radio now, though there are still quirks you need to work around.

I've learned that I have to pay very close attention to my sending cadence when working CW with the sBitx. The keyer isn't as forgiving as a traditional Curtis-style keyer circuit, and it will send errors if you're not careful with your timing. Knowing this limitation, I work much harder to stay at one speed setting throughout a contact when possible. It's easier to develop muscle memory and consistent sending rhythm at one speed rather than constantly adjusting the keyer speed up and down as I might do with other radios.

With a traditional Curtis keyer, minor variations in your paddle timing get smoothed out by the keyer circuitry and everything sends cleanly. The sBitx will occasionally miss characters if you vary your speed too much, if you slow down suddenly, you can actually outrun the radio's keyer circuit and it won't register that you asked for a "dit," so it leaves it out. This isn't a deal breaker, but it does mean the sBitx requires more disciplined sending technique than most modern transceivers.

I do tend to make more mistakes with the sBitx than I do with other more traditional Morse code radios, and I think all of this traces back to the timing limitations from the Raspberry Pi's scan cycle. But it's getting better with each software update, and for a radio that does CW, SSB, and all digital modes in a package this small and affordable, I'm willing to work around the keyer quirks.

Amateur radio operator in orange shirt operating Yaesu transceiver at picnic table during multi-operator POTA activation — Chas operating his Yaesu rig from the adjacent picnic table. His vertical antenna is behind me and to my right. My wire antenna is behind him.

WK4DS David Saylors operating POTA activation with multi-operator setup visible in background at Hillsborough River State Park — My operating position in the foreground with Chas visible about 30 feet away in the background—close enough for a park-to-park contact but creating some RF interference challenges.

20-Meter Band Issues: IRF520 vs IRF510 Amplifier Problems and Receiver Front End Overload"

The final two photos show a couple issues I've been wrestling with on my sBitx. The first image shows my sBitx operating on 10 meters with lots of noise lines visible in the waterfall display. These noise lines are coming from Chas transmitting Morse code on a different band, his signal is getting into my receiver and creating visible interference. I don't remember exactly what band he was on, but the important lesson here is that antenna placement matters tremendously when you're running multi-station setups like this one.

sBitx v3 screen showing FT8 digital mode waterfall on 10 meters with European DX contacts including Spain and Canada during POTA activation — sBitx running FT8 on 10 meters (28.074 MHz) showing the noise spikes from Chas transmitting on a different band nearby 9in the waterfall) this is what front-end overload looks like in a multi-op field setup. The vertical lines in the waterfall are RF bleed-through from his station 30 feet away.

Be mindful of where you place antennas if you're operating a multi-operator event. We were only 30 feet apart, which is far too close for optimal isolation. I was still able to work many contacts even with this persistent noise coming through, though. This is something you learn to work around if you're going to be an amateur radio operator in a multi-operator event of any kind…think Field Day here. It's just part of the game, so you expect it and adapt. We could have used bandpass filters to eliminate most of this interference, but I didn't bring mine to the park.

The next photo shows my sBitx on 20 meters, and on 20 meters my radio has a persistent issue that I'm still troubleshooting. I'm beginning to believe it has to do with the IRF520 MOSFET transistors that I used in the power amplifier section when I built this radio. These IRF520 transistors have significantly more internal capacitance than the IRF510 transistors that Farhan originally specified in the revised amplifier design. I think this extra capacitance is causing the amplifier to oscillate, and that oscillation is what you're seeing as the noise signal in the photo.

sBitx v3 waterfall display on 20 meters CW showing noise from nearby transmitter interference during multi-operator POTA setup — sBitx on 20 meters CW mode (14.061 MHz) showing the noise from what I am suspecting is from oscillating mosfets.

Here's the interesting part: as the radio warms up during operation, this spurious noise signal moves down in frequency within the 20-meter band. If I want to push it out of the way temporarily, I'll switch to 40 meters or 80 meters and run FT8 for a few minutes. You generate more output power on those lower bands, which heats up the amplifier section faster. Usually, if I just run FT8 first thing when setting up, it warms up the transmitter enough to push the oscillation down to below where I normally work CW on 20 meters anyway, giving me a temporary workaround.

This isn't a permanent solution, obviously. I'm convinced I'm going to have to address this capacitance issue when I get back home, probably by swapping out the IRF520s for the specified IRF510s or adding additional filtering to the amplifier circuit. But for now, knowing the workaround lets me keep the sBitx operational in the field for POTA activations, which is what matters most.

Multi-Operator Challenges: RF Interference and Antenna Placement

Operating two stations in close proximity taught us several valuable lessons about multi-operator setups. The biggest challenge was RF interference between our stations. With antennas only 30 feet apart, we experienced significant front-end overload, when Chas was transmitting on his station, I could see his signal bleeding through into my receiver on completely different bands.

The sBitx has a somewhat easy-to-overload front end compared to more expensive commercial receivers, which made this problem more pronounced. But even with a better radio, operating this close together without bandpass filters or careful band coordination is asking for trouble. The solution for future multi-op activations is simple: either space antennas much farther apart (100+ feet minimum if possible), or operate on bands that are far enough apart in frequency that filter roll-off provides natural isolation.

The position of your antennas matters just as much as the distance between them. If we'd oriented our antennas at right angles to each other instead of parallel, we might have achieved better isolation through pattern nulls. These are the kinds of things you learn by doing, and they apply equally to Field Day operations where you might have multiple stations running simultaneously.

Despite the interference challenges, we still made excellent contact numbers. Multi-operator POTA activations are worthwhile because you can cover more bands simultaneously, operate different modes at the same time, and keep the activation going continuously while one operator takes a break. Just be prepared to work around the RF challenges that come with the territory.

Who Should Activate This Park?

Hillsborough River State Park is an excellent choice for both first-time and experienced POTA activators. Here's why:

For beginners: The $4 entrance fee is minimal, facilities are excellent with clean restrooms and covered picnic areas, and the tree coverage makes wire antenna deployment easy. You don't need to hike to reach good operating locations…everything is accessible by car right off the main loop road.

For experienced activators: The park's location north of Tampa puts you in a good spot for both domestic and DX contacts. The tall pines support wire antennas at significant heights, and there's plenty of space to spread out if you're running a multi-operator activation.

Best practices for K-1488:

Arrive early morning (8-10 AM) or late afternoon (3-5 PM) to avoid midday heat and sun glare
Bring sunshade or canopy, there's limited natural shade at the picnic tables
Plan for 2-3 hours of operating to get a good contact count
Cell coverage is good for self-spotting on the POTA network
Spring and fall offer the best weather conditions

If you're in the Tampa Bay area and looking for an easy, productive POTA park with good facilities, Hillsborough River State Park should be on your list.

Activating Hillsborough River State Park proved to be a highly productive POTA outing. Between Chas and me, we logged well over 100 contacts using QRP power and simple wire antennas…proof that you don't need high power or expensive gear to have success in Parks on the Air. The 65-foot EFHW at 35 feet worked exceptionally well, the Penntek TR-35 remains one of my favorite field radios for CW, and the sBitx v3 continues to impress despite some remaining amplifier quirks on 20 meters.

Key lessons learned: antenna height matters more than output power, multi-operator setups require thoughtful antenna placement to avoid interference, and limiting transmit power to 10 watts keeps your batteries happy all day. If you're looking for a beginner-friendly POTA park in Florida with good tree support and easy access, Hillsborough River State Park (K-1488) is an excellent choice.

Have you activated K-1488 or other Florida state parks? Share your experiences in the comments below, I'd love to hear about your favorite POTA locations and antenna setups.

Want more POTA activation reports and technical amateur radio content? Check out my other WK4DS blog posts for detailed equipment reviews, antenna builds, and field operation tips.

Frequently Asked Questions About POTA Activations

What is Parks on the Air (POTA)?

Parks on the Air is an amateur radio operating activity where hams set up portable stations in state and national parks to make contacts. Activators (operators in parks) try to make at least 10 contacts to qualify the activation, while hunters (operators at home) try to contact as many parks as possible. It's similar to Field Day but focused on public parks and conservation areas. POTA encourages hams to get outdoors, test portable equipment, and promote amateur radio to park visitors. The program started in 2016 and has grown to include thousands of parks across the United States and internationally.

How do you activate Hillsborough River State Park for POTA?

To activate Hillsborough River State Park (K-1488), you need to set up your amateur radio station within the park boundaries and make at least 10 contacts. Pay the $4 entrance fee at the ranger station when you arrive, then find a suitable operating location with trees for antenna support. Most activators set up at picnic tables near the main loop. Operate from battery power or a generator, no AC mains allowed for POTA activations. Log your contacts using a smartphone app like HAMRS or POTA Logger, then upload your log to the POTA website within a few days. The park has excellent tree coverage for wire antennas and is open from 8 AM to sundown year-round.

What is an EFHW antenna and why use it for POTA?

An End-Fed Half-Wave (EFHW) antenna is a wire antenna that's fed at one end through a matching transformer (typically a 49:1 unun), making it incredibly easy to deploy in the field. For POTA activations, EFHWs are popular because they require no ground radials, work on multiple bands without a tuner if cut for harmonically-related bands, and can be thrown into trees using a throw line and weight. My 65-foot EFHW works on 40m, 20m, 15m, and 10m, covering the most productive POTA bands. Getting it 35 feet high significantly improved propagation compared to running the same antenna closer to the ground. A properly deployed EFHW antenna at height will often outperform a vertical antenna at ground level for DX contacts.

Can you run two stations at the same POTA activation?

Yes! Running multiple operators at the same park location is allowed and encouraged in POTA. Each operator logs their own contacts and submits their own activation log. Chas and I each operated our own stations about 30 feet apart, which let us cover different bands simultaneously and maximize the total contact count. However, you need to be mindful of RF interference between stations. With our antennas so close together, I experienced front-end overload on my sBitx when Chas was transmitting on nearby bands. Solutions include better antenna separation (100+ feet apart if possible), using bandpass filters on receivers, or coordinating to operate on widely separated bands like 40m and 10m simultaneously.

What's the best QRP radio for POTA activations?

For CW-only POTA activations, the Penntek TR-35 is exceptional. It's lightweight (under a pound), battery-efficient, has outstanding CW break-in, and is nearly indestructible, perfect for field operations. For multi-mode operation covering CW, SSB, and digital modes, the sBitx v3 offers incredible value and capability in a portable package, though the CW keying requires careful technique and practice. Other popular POTA QRP rigs include the Elecraft KX2/KX3 (premium price but premium performance and battery efficiency), QRP Labs QCX-mini (CW-only, ultra-portable and inexpensive), and the Xiegu G90 (good SSB performance, acceptable CW, built-in tuner). Choose based on your preferred modes, budget, and how much weight you want to carry into the field.

How many contacts should you expect from a POTA activation?

Contact numbers vary widely based on propagation conditions, time of day, your operating skill, and whether you're spotted on the POTA network. A successful activation requires at least 10 contacts to count, but most activations yield 20-40 QSOs in an hour or two of operating. Our 100+ contacts in one afternoon between two operators was excellent, partly because we covered multiple bands and modes (CW, FT8) and had good propagation to Europe on the higher bands. If you're new to POTA, expect 15-30 contacts on your first few activations. Using CW typically yields more contacts than SSB due to pile-ups from hunters chasing parks, and FT8 can be productive when propagation is marginal or when SSB isn't getting through.

My 66 contacts plus Chas's 52 gave us 118 total QSOs from K-1488 on February 17, 2026. Ten of mine reached six countries across two continents, all at 10 watts or less.

You can help support this channel by using these Amazon Affiliate Links as well:

QRP/Portable Radios:

Antennas & Tuning:

CW Equipment:

Power & Accessories:

Organization & Transport:

BONUS ITEMS

David / WK4DS

Overall, today we had a wonderful day and made many contacts and was able to test antennas and enjoy ourselves in the warm Florida sun far from home where all the cold weather and dreariness is at. So until next time, get your radio out and go power it up and make a contact on it. That’s why you bought it after all.

Chas grabbing a photo from his perspective for posterity! HaHa! Look at all that stuff I brought!

David Saylors 3/4/26 David Saylors 3/4/26

Over 100 QSOs at Chito Branch US-5524 POTA Activation AAR

Today saw me working on my kilo at Chito Branch again. I figured I would net 30, maybe 40, contacts considering the band conditions and the problems I was running into, but nothing prepared me for what happened today…

The Antenna and Radio Setup

I arrived at the park after hitting a pretty heavy traffic jam this morning a little frustrated since I am attempting to secure the kilo before we leave town for the rest of the year. I get to the park and there is not a single person on site other than me, which gives me the pick of the litter of locations. I immediately go about setting up the antenna and tuning it.

I also noticed today something about the antenna that was of interest to me. I will be investigating it further and writing about it soon. It is that the characteristic impedance of the vertical can not be made purely 50 ohms without a reactive component at all. It simply doesnt work. I testing it for a few minutes as I was curious and as I would tinker with the vertical and the radials to move the plot to purely resistive, it would move the frequency of the antenna off at the same time (stands to reason) but I couldn’t get it to a nice clean 50 ohms no matter what I did. I tinkered with it and the radials till I got the null on frequency and the SWR as low as feasible and moved on to the radio.

After I finished setting up the antenna, I chose to use the TenTec Scout 555 amateur radio and only pulled the 15 and 20 meter band modules for today’s activity. I wanted QSOs in the log and not exotic bands today… I had made a mistake last night though, this radio is temperature sensitive to some degree, it will drift in frequency (mine wanders slowly up) till it warms up from use. So when I am running the keyer and the radio is in transmit a lot calling CQ, the radio heats up in the back and slowly that heat creeps forward in the case to warm the rest of the electronics. Once warm I find the radio to be very stable and work exceeding well, but until it does, I have to watch it and turn the VFO down a little at a time till it is warm. This is what I had to deal with today

The POTA Activation Begins…

People were sending me notes in the spots on the POTA website about my frequency so I would know about the drift. I love how the hunters are there for you all the time, even once they have you in the log. That is awesome camaraderie if I must say so. I racked up a staggering 35 QSOs in short order! It was going so well that I figured I would hop onto 15 meters and see if I could get 40 or 45 before I ran out of time… What happened next blew my mind. After I worked those 35 stations it is like the radio simply turned off, I don’t know if I had worked everyone on the band or if the band had started to close, but I could no longer hear anyone calling. So I called CQ a couple more times and finally after not hearing anyone else for a coupe of cycles, decided to QSY to 15 meters.

1/4 wave telescoping vertical antenna with radials — The ¼ wave telescoping vertical antenna was simple and effective today.

TenTec Scout 555 Amateur Transceiver with Begali Travler CW Key

15 Meters Gets Sporty!

Once on 15 meters with a warm radio, I set off with calling CQ on a clear frequency. I called for maybe two or three minutes before I started getting replies…and then I got more, and more, and more till I had a genuine pileup on 15 meters! There was times when I am sure I could hear at least ten stations calling at once and this happened a coupe of times today! I also knew from prior experience that 15 meter is kinda where I start really hearing DX stations when the band is in good shape so I was kinda listening for stations with callsigns that start with letters other than A,K,N and W. I have found that after doing POTA for a while that my brain instinctively listens for one of those letters first in the call. If I don’t hear one of those 4 at the beginning then something in my brain trips and I only get the last 2 or 3 letters of the callsign and require a repeat…unless…I am on 15 meters and above.

It is really rare for me to even hear DX with the antennas I use for POTA until I get up to 21 mhz or higher. To be honest, I am surprised I hear them at all with some of the antenna designs I use. The ¼ wave vertical pictured above is a prime example, I am pretty sure this antenna needs to be a good bit higher in the air for a good DX take off angle, but here we are….

Here is the list of the DX I worked today from a POTA park:

DX Countries Worked:

Working DX on simple antennas is one of the joys of amateur radio. The ARRL's guide to HF propagation explains why 15 meters can be so productive for European contacts from the US.

Venezuela - YV1GIY
England - G0LLU, G3NKQ
France - F6CAX, F6OYU
Spain - EA4MZ
Belgium - ON5JT, ON4ZD
Czech Republic - OK1MGW, OK1XC
Germany - DF2PI
Cape Verde - D4HP
Belarus - EW6GB
Russia - R1QBD/3
Israel - 4Z4DX
China - SH2NR

hamrs logbook application — I use HAMRS for my POTA logging.

AAR POTA Wrap Up

As you can see, I was hearing people from all over the world! I couldn’t believe some of the ones on this list. I don’t think I have ever worked Cape Verde before! He was really weak too, I could just make out the call and signal report after him repeating it a few times, but we got it done! Europe would come booming in with spurts of band openings apparently as I would work two or three at one time then it would go silent in the EU for a while then it would happen again.

Now this is not to say the band was in perfect condition. There was considerable QSB (fading) of the signals today, but it was manageable with a decent set of headphones and a properly adjusted radio. I could hear all but maybe 3 stations that I could hear at all. Of those three, one of them I almost got but then it faded out completely. I was so close too… Anyway, the calls just kept coming in and over the next hour I hit 50 then 60 then 70 and the log just kept building. I use HAMRS for my POTA logging and it shows the total in the top corner like a little scoreboard...

I finally got to something like 78 and had a couple of duplicate calls by now so I wanted to finish with a solid 80 and started really working towards this new little goal I had thrown up. Then I did it and then ran right past 80 to almost 90! It just kept happening! 15 meters was on fire today! I finally got to about 98 and I was almost out of time so I decided to stop at 100 even if I didn’t account for the duplicates. 98 is better than being late for picking up the XYL (the wife)… haha. But then I hit a little run of 5 and landed finally on 103 and the goal being reached, I called QRT and powered off the station. This is what I love about POTA, the callers were coming in from everywhere.!

HAMRS logging software qso map — Screen capture from the HAMRS logging software QSO map.

This map blows my mind, all of those calls were worked on a 30 year old, 40 watt TenTec Scout 555 radio (I turned the power down from factory spec for a reason)that has to warm up to stay on frequency, with an “outdated” mode that appears to be very NOT outdated at all, with a less than ideal antenna! So with all this I have to say, just get something together and don’t worry too much about if it has perfect SWR or if the antenna is “high enough” for DX, obviously that don’t matter when the band conditions get right! Now of note, most of the DX (I think almost all of it other than Venezuela, is 15 meters only) also all of the west coast if 15 meters as well as several of the ones due north of my position.

Elated at the fact that I had put over 100 calls in the log toward my kilo, I hurriedly broke down the antenna and packed the radio away and drove off to get the wife from school. Now if I can just repeat this again tomorrow…haha.

How many watts does the Ten-Tec Scout 555 output? The Ten-Tec Scout 555 outputs 50 watts from the factory, I have mine “turned down” to 40 watts as this is a simple adjustment and helps protect the radio from high SWR issues in the field, which is more than adequate for POTA activations and working DX on CW. Despite being a 30-year-old radio, it performed exceptionally well during this activation and many others in the past.

What bands work best for DX during POTA activations? 15 meters (21 MHz) and above typically offer the best DX opportunities during POTA activations (for me at least). At US-5524, nearly all European DX was worked on 15 meters, while 20 meters provided primarily US contacts.

Do you need a perfect antenna for POTA DX contacts? No - this activation proved that DX is possible with simple antennas. Using a basic quarter-wave vertical with radials at ground level, I worked 12 countries across Europe, South America, Africa, and Asia…in one sitting.

Why does the Ten-Tec Scout 555 drift in frequency? The Scout 555 is temperature-sensitive and drifts slightly as it warms up during transmit cycles. Once warm (after 15-20 minutes of operation), it becomes very stable. Simply adjust the VFO slightly downward as it warms. The radio drifts in frequency due to component value changes as they warm up, this is common in older equipment or less sophisticated designs like the Scout 555. Things like crystals will change frequency when they get warm, other things like capacitors will also change value with temperature if they are not specifically stabilized versus temperature.

What is the best logging software for POTA activations? HAMRS is excellent for POTA logging - it's free, works offline, handles POTA references automatically, and generates helpful QSO maps. It also exports to ADIF format for easy upload to pota.app. Is it the best? For me it is…

Hope you enjoyed this AAR, leave a comment and I look forward to hearing from you in a future one,

You can help support this website by using these Amazon Affiliate Links:

QRP/Portable Radios:

Antennas & Tuning:

CW Equipment:

Power & Accessories:

Organization & Transport:

BONUS ITEMS

David - WK4DS

David Saylors 2/10/26 David Saylors 2/10/26

Joint POTA Activation with NA2B at Moody Branch: 104 CW Contacts in 4 Hours

Today I went to a POTA park to meet up with Chas NA2B, another amateur radio operator that lives just down the road from Chito Branch nature Reserve where I have been spending a lot of time here lately. He saw I was at the park on the spot page and simply hopped in the car and drove over for an eyeball QSO and to see if I wanted to meet up with him at some point and setup for an activation.

Today I had the pleasure of meeting Chas NA2B for our first joint POTA activation at Moody Branch Wildlife Management Area (US-6317) in Florida. What started as a chance encounter on the POTA spot page turned into a memorable 4-hour operating session that netted 104 total CW contacts between our two stations.

This blog post will be an amalgamation of both discussing the activation as well as my new friend.

Planning the Activation

We communicated a good bit over the past week via text to line up a good day, (turns out every day is a good day for Chas…haha) and chose Tuesday as I had some business to attend to on Wednesday and the weather was way warmer than the previous day. The weather actually turned out to be about perfect to be honest about it. We agreed on Moody Branch US-6317 and 9:30 as the start time. We had planned to operate till about 2 if things were going good so on the day of, I load up the truck and head out. It takes about an hour to get there from where i was staying so I stopped and grabbed coffee and snacks along the way. Who doesn’t want a caffeinated CW op on the other end of their QSO???

When I get there I am greeted with the standard issue Florida DNR signage and to my amazement there is a pavilion for us to operate from! Now to be fair, Chas had told me about it and the proximity to the parking lot. You see it was literally 15 feet from my truck to the table. Having the table this close allowed for an incredible amount of gear to be brought out. HaHa

Chas had already arrived and was setting up in the back of the pavilion so that I could have the closer spot and access to some really good trees to hang my antenna in. I decided to setup the antenna “properly” by putting the antenna tuner at the antenna instead of at the radio. This should provide better radiation than using the tuner to match the feedline as part of the antenna system. I simply set the case on the ground and set the tuner on top of it and tied the antenna wire to the case itself. The distance was about 50 feet from the table so I had to couple both of my longest coax cables together just to reach the tuner out by the tree.

The Setup: Remote Antenna Tuner Configuration

I put the antenna tuner way out here on purpose. The remote tuner setup keeps the feedline from becoming part of the radiator. This is important at it creates a more efficient antenna overall.

Since it was so far from the table, I just left the nanoVNA with the tuner so it would be nearby when I wanted to make band changes, of which there was many!

I strung the wire up like an inverted L type from tree 1 to tree 2 and tuned it for 40 meters to start with. Today I chose to start there as I was wanting to make contacts on all the bands I could with the Penntek TR-35 QRP radio. I also decided at the outset that I would work bands other than 20 meters today to see what I could come up with. I usually seem to have great luck with all the bands…other than 60 meters so far… haha. I also chose to run 10 watts or less all day too…well except for 40 meters, I ran 40 watts on 40 meters and still only made one FT8 contact there… lol. The band was just too noisy for me to hear anyone.

Equipment: QRP vs. Comfort

I only ran 10 watts or less the rest of the day because I didn’t have my large battery with me that I bring to power the sBitx at full power. I only had my 8 Ah battery and I didn’t want to deplete it early. I also had the 3Ah battery for the TR-35 and used it with that radio, but those were the power sources I was constrained to. This made me have to work a little harder for contacts, but it also made it a lot more fun to get DX stations in the log! I got at least 2 European stations in the log so I know it doesn’t take a ton of power to do it.

pota two operators — WK4DS (left) and NA2B (right) running simultaneous CW pileups on different bands at Moody Branch

Once setup I used two radios, the Penntek TR-35 QRP rig and the HF Signals sBitx V3. Both of these radios are cool in their own respect. I like the sBitx because I can run FT8 without needing to also connect a computer to the radio. The sBitx will internally log the contacts too so I could theoretically do an activation then when I get back home, down load the contact list and reformat it in ADIF and send it to the POTA site. That is kinda cool. The Penntek TR-35 is small, light weight and has a great receiver in it as well as awesome filtering. This little radio has everything you need and nothing you dont.

Above is me and Chas running pile ups on two different bands at once! We were both running CW today and at times I struggled to hear as my side tone and his were the same. I solved this by adjusting the side tone up a little so then mine and his were different ever so slightly and I could hear mine easily again. I think Chas stayed on 20 meters the whole time today. He racked up 61 contacts with the simple wire antenna. What a day in the field!

sbitx hf sginals — sBitx V3 running FT8 with new color-coded software from the open-source development team

This is what you see with the latest software release from the open source team on Github. This software has been made VERY good by this team of dedicated people and if you want to use this software yourself, just follow this link to JJ’s github page to learn more.

pota field station — NA2B's minimalist CW station: paper logging, pencils, and a clean operating position

Chas had a really clean operating position today. He had plain pencils, which will ALWAYS work, a pencil sharpener and notebook for log data. He was in a blissful state. I also like the battery pack he has too. If I had brought my 36 Ah battery, I would have brought the Scout 555 out and ran it as well. Maybe forgetting it was a sign that I needed to let that radio rest a little…haha. His station looks so clean though, I was impressed.

My station on the other hand looked like I set off a “ham-grenade” lol… I had the logging computer, the foldable keyboard for the sBitx and the whole Penntek station was just piled in the orange storage case. Along with all that, I also had all sorts of other stuff that isn’t in this photo scattered around the table… It was kinda crazy how much crap I brought out.

Operating Highlights

Chas setup his camera and grabbed this photo of us below for the blog. I like how his station has one box on the table and mine is covered in stuff! HAHA!

I will be honest, it was a lot of fun just hanging out while doing the activation. I do so many of these by myself that I forget that I can have someone with me while I do this.

We didn’t get in a hurry, we just took our time and whatever calls got in the log is what we got. There were a couple of time we both had decent pileups to work through, him more so than me as he had more power and 20 meters typically has more operators on the band. It wasn’t about QSO count…till it was… but all day we just made contacts and played radio.

Right before we finished for the day, I asked Chas how many contacts he had. Chas had 60 calls in the log and I had 38. I told him that we needed to have an even 100 calls between us before we stopped for the day. This total number of QSOs was completely arbitrary, but a cool little milestone none the less so we pushed on for a little longer. We finished the day with 104 total calls in the logs. Win! Chas had 61 as a final count and I ended up with 43! What a day!

two operator pota — Multi-operator POTA setup at the pavilion - note the contrast in station complexity!

After about 4 or 5 hours of fun and games, we decided to break down and head back to our wives to get some lunch. It was a great day and I am glad I made a new friend as well.

Activation Summary:

- Park: Moody Branch WMA (US-6317)

- Operators: WK4DS & NA2B

- Total Contacts: 104 (43 WK4DS + 61 NA2B)

- Mode: Primarily CW, some FT8

- Bands: 40m, 30m, 20m, 17m, 15m

- Radios: Penntek TR-35 (QRP), HF Signals sBitx V3, Yeasu FT-891

- Power: 10 watts or less (QRP), 40w on 40m, 50 watts on 20m

- Antenna: Inverted L wire antenna with remote tuner, (Chas ran a random wire)

- Duration: 4-5 hours

You can help support this website by using these Amazon Affiliate Links:

QRP/Portable Radios:

Antennas & Tuning:

CW Equipment:

Power & Accessories:

Organization & Transport:

BONUS ITEMS

WK4DS - David

David Saylors 2/9/26 David Saylors 2/9/26

Ten-Tec Scout 555 60m Band Module: IF Filter Redesign & Final Testing [Part 4]

Today saw me finish the TenTec Scout 555 60 meter Band Module Project in the workshop, now it is on to phase 2, testing in the field… I had wanted to rework the filter in the IF stage as it was not great from before. I was able to get a signal out of the radio, but the filter shape left something to be desired…

This is the final episode in my Ten-Tec Scout 555 60-meter band module series:

- Part 1: Initial Conversion and Filter Design

- Part 2: Crystal Selection and Mixer Circuits

- Part 3: Field Testing and Troubleshooting

- Part 4: IF Filter Redesign (this post)

The first chart image is of my filter after I got the radio to work. This is not what a bandpass filter should look like. The lower photo is of a factory TenTec VERY narrow bandwidth 40 meter bandpass filter. Turns out, this is almost impossible to replicate with discrete components that are not adjustable…as you will see. They used two tunable inductors to achieve this filter shape. I almost went to the trouble of adding some trimmer capacitors to mine, but as you will soon see, I felt it wasn’t needed. I soon learned what a filter Q is and why it matters when your trying to build a filter. I used some online calculators to get the component sizes for the filters and after messing around with a couple, I found one of the calculators had came up with numbers that were actually able to be made in my shop.

Armed with this information I decide to breadboard this filter first so I could tinker with it before soldering it to the band module circuit board. This, as it turns out, is a terrible idea if you plan to simply transfer the parts to the board and solder it all together. There is SO much stray capacitance and inductance at RF frequencies with a breadboard that you can build up a circuit, but when it comes to making the final item on perf board or Manhattan style, that you WILL use different values.

Looks good doesn’t it? Well look at the plot below! It actually looked great! It did have some insertion loss that I was not super happy about, but that plot looks great! Yes, the one inductor is hand made, I didn’t have one small enough in my little kits to work here I so wound one for the job. Notice how long the leads are on those components, that will come into play very soon…

I may have gotten a little aggressive with the passband width… I think it was set to 200khz or maybe 500khz, but it was not much. I think the values I put into the online calculator were 5.4mhz center frequency, 500khz bandwidth and 3 LC stages in a “T” configuration. The bottom line on the chart is -70dB which is unbelievable! This thing was incredible! So I get the 60 meter module out and take it apart and strip out the old filter I had previously built wholesale leaving a clean slate for the new filter…

After I had the old filter gone and cleaned up a little, I cut me a pad as the new filter layout and the TenTec layout are different so I wanted to not have to permanently alter the circuit board other then removing the old components. This pad became the central connection point for the three stages. A little hot glue and I was in business! I simply tinned the whole top of the pad so I could land part leads where ever I wanted on it. This worked really well…much better than the filter I am about to build as it would turn out.

SIDE NOTE ABOUT MODIFYING SCOUT BAND MODULES:

What I am pointing out in these two photos is a home made Via that I added. You see, when you remove the canned tunable inductors from the board, turns out you break the grounds. TenTec decided that since these things were going to be here anyway, might as well use them for something. So they apparently decided to make them connect one ground plane to another in a couple of places on the board. Once you remove the cans, you lose a critical ground path…or two. I took a finger drill and a very small drill bit and drilled a hole from one trace to the ground plane on the opposite side(I am confident these are only two layer boards), then I soldered a bonding jumper wire in the hole so both planes would once again be connected again and all the stuff would continue to work properly. You also get to see the old homebrew filter in the below photo as a bonus.

Below is the result of me simply attempting to move the parts over to the circuit board and soldering them in place… What a mess. I started with the exact parts you saw on the breadboard, but when I connected the nanoVNA to the filter I found the center frequency had moved up 500khz! It was now pushing my desired frequency out of the passband!!! I was seeing something like 16dB of loss at the desired frequency.

This is the world of ultra high Q passband filters made with inductors and capacitors I guess. Once I removed all the stray capacitance from the breadboarded system, all the capacitor values went down enough to make the filter not usable. That is why you see the mess below, I didn’t have room for the trimmer caps I have on hand so it was good ole trial and error method instead to get the passband in the right spot. To be fair, this mess actually worked, it just had something like 12 or 13dB of insertion loss in the filter which made the output power go way down. I used the amp meter to check it and the current draw on transmit with this filter was 1.8 amps and the current draw with the factory 40 meter band module was 9.3 amps. So I took a break and grabbed some food and went back to the drawing board…

I am going to admit something here that might make some people unhappy with me…I decided to use Claude AI to see what it would come up with for a filter design. I gave it all the parameters I had used earlier and (since it is a chatbot after all) had a conversation about what my goal was. I decided to move the bandwidth out to 1mhz giving me a decent shot at making a working filter without adjustable parts and using only what I had available on site.

This AI model came up with a “T” filter but instead of the center 2 LC components being in parallel, they were in series and so I built it. It tested really bad as far as rejection goes as it only attenuated about 8 or 10dB across the whole band and looked more like a poorly designed high pass filter instead. This did give me some inspiration though. So I went back to the online calculators that are there to figure part values for you and changed my approach. I went to this website and just made a low pass filter and then a high pass filter and coupled them together with an inductor. Why did I choose an inductor? Because all the capacitors I tried kept increasing the losses in the filter output is why. As it turns out, if you attenuate the IF signal in the radio the output power get lowered and the radio goes “deaf”…

Below is what I came away with finally. Yes, only 3 inductors and two capacitors.

Below is the filter shape for this simple filter design too. It is a lot better than what I started with and I was able to build it with parts that I had available to me at the time. Could the passband be narrower? Yeah, it could, but I am not going to throw too much shade at this filter. This is what ham radio is all about in my book, experimentation. The marker is at 5.64mhz which is 250khz above the highest place I can transmit so I know this filter wont attenuate my signal and the radio will work as it should.

The original values for the filter ended up being wrong, but I simply did what I did in the previous filter build and just used it as a jumping off point and started switching out parts one at a time with different values. This tactic coupled with looking at the nanoVNA to see what the new part did to the filter shape gave me the results you see. At first I didn’t write down what I had done, but it quickly became apparent I needed to note what I had done and so things progressed much more quickly once I did.

The above photo ( bottom of the second page ) is what I started with on this part and the lower photo is what I ultimately ended up with for the actual parts I used to build the filter. You can see where I was trying all sorts of stuff to get a working filter, these are not the only sketches either…

This is what I ended up with ultimately to get the filter shape above. The impedances are wrong, I am sure as I didn’t take them into consideration at all, but the radio is working correctly now (from what I can tell) and transmits almost at full power. Shoot, they could be right and I just got them right by accident, I really don’t know to be honest.

This is the output power draw now for the 60 meter module on the same radio as the 40 meter module previously compared. I can live with that! I checked it when I got into the shack at the house and it is a little over 35 watts into a 1.3:1 SWR load. That will work just fine for me. (Note: The current reading was into a 50 ohm dummy load at the workbench so I don’t know the exact current draw in the shack.) This radio will produce more output power too, I have it dialed back on purpose to about 40 watts for the 20 meter band module that I use with this radio.

This is what the final filter looked like when I was finished building it. This looks a lot better than that mess I started out with above. Not overly complicated and generates a respectable filter shape. The radio sounds good too. So I am happy with this.

Side note about the above photo, I had noticed in my original filter design that the orientation of the inductors made a difference in the filter profile on the nanoVNA so I started marking them with a paint pen to remember the orientation. This filter didn’t seem to care too much about that for some reason but the original cared ALOT.

The side view photo shows something else the I have not mentioned in these write-ups. The filter has space constraints. The filter can not be taller than that metal post or the other circuit board with hit the parts and the parts can not go past the post either as that is the space for the output low pass filter from the other board. So parts count matters…

It feels oddly satisfying to see the finished module and to use it in the shack. All I did last night was listen to some stations having a QSO and how well it could hear them. I also dialed up the webSDR again and listened to myself calling CQ for a bit with no takers on a different channel. I know the radio is working as the listening station in Utah could hear me…

Tonight I hope to find a chance to jump into a QSO with someone and see how it sounds to them.

I hope this has inspired you to do something with your gear whether it be build a kit or modify a device to do something new or different or even to repair something you have that is not working now…shoot maybe you will learn something you didn’t know before! That is what has happened to me on this journey, I have learned a lot about how filters work and what affects them in use. I am starting to understand impedance matching the stages as well as insertion loss. A lot of things I never understood before are now becoming more clear. I also have a much clearer understanding about how the TenTec Scout 555 radio works as well…

Thanks for following along on this 4-part journey! If you build your own 60-meter module for the Scout 555, I'd love to hear about it. 73!

You can help support this website by using these Amazon Affiliate Links:

QRP/Portable Radios:

Antennas & Tuning:

CW Equipment:

Power & Accessories:

Organization & Transport:

BONUS ITEMS

WK4DS - David

David Saylors 2/7/26 David Saylors 2/7/26

Ten-Tec Scout 555 60m Band Module Build: Final Filter Tuning & Field Testing [Part 3]

Today I took the newly minted 60 meter band module for the Ten Tec Scout 555 out on it’s maiden voyage to a POTA activation. I made a contact in the shack with it before leaving on my short trip to Florida so I felt confident it was ready to use. Today we are discussing what happened and what is going on from there with the 60 meter band module project. (Spoiler Alert: It kinda wasn’t really ready yet…)

As you can see from the spot page report below, I was the only one on 60 meters this morning and it was roughly 9:45 (might have been 10 to be honest, I cant remember) local time before I got everything setup and running. This made 60 meters not a great choice to be honest for a daytime band. The 60 meter band is a great evening and really early morning band, but once the sun comes up these low bands tend to get really noisy. The band noise was quite low to my surprise today. I usually get a good bit of man made noise in this spot so I was pleasantly surprised when the noise floor was really low…or the band was closed. Who knows at this point?… I am starting to lean towards the band being closed as I couldn’t hear the FT8 crowd either, and those guys are ALWAYS on the band if it is open at all.

Undaunted by this and the lack of any kind of signal on the band, I setup and started calling CQ…and called …and called… then I finally got a station in North Carolina ( WA4CHJ - thanks for answering me, I really appreciate it. ) and with that I had a call in the log on 60 meters with a Ten Tec Scout 555!!! I can’t be certain this has been done by someone else, but as far as I know, I am the first to make that happen! After calling CQ for about 7 more minutes with no answers, I noticed that the ALC light was not coming on when I would key the radio and it was showing about 20 watts forward power on the built in meter. I checked the SWR and it was fine so it had to be in the module. I tried calling for a little longer and started getting an odd kind of “hashy” crackle on the CW sidetone and when it would make this sound the power would go up to the normal level and the ALC would come on…Upon this realization, I decided it would be better to sideline the module till I got back to the work bench next week instead of risk damage to the module or the rest of the radio. It also occurred to me that the RBN never heard me, not one time, while calling on this day so the band must have been closed…

You gotta admit though, that setup below is kinda sweet… Also the frequency is tuned off by the side tone (this is normal for the Scout 555) so it is actually on 5.3305 mhz in this photo. (I checked it with my Omni-VII before leaving home so I knew it was on frequency)

I setup a long wire today since my vertical will only tune to 40 meters with the home-brew load coil and I was a little strapped for time and just used an MFJ manual tuner instead. This allowed me to get a 65’ wire up in the air and a couple of radials and run with it. I was able to tune it well into the 60 meter band with the null covering the entirety of the band space so no tuner changes were needed as I moved around in the band.

SIDE QUEST:

This little segment will be about the rest of the activation for my readers that follow those as well.

Today was a great day…once I moved to 20 meters! Turns out 20 meters was alive and well today with only about 6 CW activators on the band. This gave me plenty of room to find a nice quiet frequency as well as lots of hunters were out today as well. I tuned up on 14.047 mhz and started calling CQ, I think it took two calls max to call in a extraordinary pile up for me! The stations were deep and strong! I swept aside my normal pleasantries for the most part and compacted the closing to what I felt was a minimum and the calls just kept coming in! I worked 49 calls in 41 minutes! That is a record for me! At this point I literally called CQ one last time to make sure there was no one else waiting and got no replies so I immediately called QRT and shut down the radio. I was actually out of time and had to get the rig packed up since I needed to pick up the wife from class. This had to be the fastest 49 calls in the history of WK4DS amateur radio in my totality of radio… haha.

MFJ was a company that some complained about (Surely you have heard them called More Fine Junk) but to be honest, everything I have ever bought that they made has worked exactly as described and was pretty reasonable in price too. I hope someone fills these shoes for the future hams coming into the hobby, this little tuner is amazing for what is in that tiny little housing. It tuned this long wire just fine and didn’t need huge capacitors or inductors to do it. Not to mention it was really economical too. Good kit is hard to find so if you plan to do POTA in the field, I recommend one of these in the box of stuff, it WILL bail you out one day. This tuner has bailed me out a couple of times now…

A throw line, a weight (that I made in the machine shop out of scrap stainless steel) and 65’ of wire made for a lot of fun today.

You can’t really tell it in the photos, but I did use my vertical antenna truck mount. I used it as the truck side anchor for the long wire and strung it up into the tree you saw earlier. This turned out to be really convenient I must say.

SIDE QUEST ENDED:

Back to the project at hand…

A week later and back in the shop at home with the band module on the work bench again and a Scout 555 in the shop now instead of the ARGO 556 to give me full power (40 watts) into the module (I pull the output power back to 40 watts to help protect the radio).

Now I can sort out the last of the details with the filters under full load. I am starting to think that the LO BP filter still needs some work as well as the signal level on the mixer output filter is REALLY high. I don’t remember the exact number but think of something like 700 or 800mV level instead of the 50mV that is supposed to be coming out. I tackle this problem first by building up the board like I had before so I could see the level coming out of the mixer filter. I had removed one of the impedance matching capacitors completely (750pf) without understanding what I had done and this was a big part of the problem with the level being so high. I did some simple math and came up with about 600pF instead of the 750pF that was supposed to be in the board since it was now tuned for 5.35 mhz instead of 3.55 mhz. I ended up using a 560pF cap and the level looked like the photo below on the base of Q16 in the radio. Remember this data is at this link if you need it as NA5N made these wonderful signal flow graphics.

Right on the money at 50mv! I will take that everyday! All the noise you see on the signal is generated in the radio as far as I could tell, all the band modules I tried today looked like this on the base of Q16…or I was picking up the noise from somewhere else, I really am not sure to be honest with you. The output from the collector looked fine though so I don’t know what is happening here. I know this is good now as the frequency in the radio is stable and doesn’t drift. Those NPO capacitors paid off! (NPO means “Negative-Positive 0 ppm/°C” or more plainly, these capacitors are stabilized so they don’t drift in value with a change in temperature) My circuit doesn’t look exactly like the original Ten Tec filter but it does work.

Below is what I ended up with for the filter circuit. I added the one capacitor that was not in the original design (the 43pf cap) and this did seem to help with the shape of the filter so I left it. I drew my filter flow direction backwards from the Ten Tec drawing but you can see the differences from the 80m filter I started with below. Also a couple points of interest here. In my 60m module (formerly an 80 meter band module), the output from the mixer chip is pin 5 on my board and not pin 4 that feeds into the filter network. If you look at the spec sheet, this is fine as both pins are output pins, but it was a curious mistake in the schematic I found while troubleshooting my module. Another curiosity to me is that the schematic shows L6 in parallel with C8 (5pf) in the center of the filter. Not one single band module uses L6… at all. The chart underneath the schematic shows a -0- symbol on each one of the modules for L6, to confirm this, I looked in three different modules and none of them have this inductor in them. It isn’t present on the 10 or 12 meter modules either as they have a different layout for their filters. This was a provision that later was deleted I suppose. Kinda neat to find things like this while doing a project. Makes you wonder why they provisioned for the inductor but never used it. The board has two through holes for the inductor as this is where I placed my 15pf cap (which made adding it really convenient.) So it was obviously designed into the system to start with… Maybe someone who was an engineer at Ten Tec back then will comment.

Excerpt from original Scout 555 owner’s manual.

With that out of the way I moved on to the output LP (Low Pass) filter that the 50 watt power amp flows through to get to the antenna.

The above photo is of a LP filter out of an unmodified 80 meter band module I used for comparison. If you will notice the roll-off is right smack dab in the middle of the 60 meter band on this particular module.

The photo below is of the 60 meter band module sweep that I am building out of an old 80 meter band module. If you will notice I have the nanoVNA set to 5.430 mhz on the marker, and it is hard to see, but the signal is at 0.05dB which is basically zero losses at the highest band position possible. This would imply that the filter would allow the 60 meter band through just fine, but it would not…

This is what the radio was sending to the dummy load after it passed through the LP filter module (above photo)… So to test this theory, I installed a different module (40 meters) and got what you see below… That is a little over 120 volts peak to peak on 40 meters. Yeah, you don’t change the output power of a Scout without a screw driver so the fact that the 60 meter band module I made is only letting a little over 30 volts peak to peak through it AND knowing that the 40 meter band module is passing over 120 volts peak to peak, tells me the 60 meter filter is choking off the energy and it is probably heating up the toroid inductors pretty good at the same time. I suspect that is what I was hearing the other day at the park when it was crackling after a while. I just hoped that I had not burned the wire on the inductors with this energy… If so I would have to rewind the inductors completely from scratch. Fortunately, I do have a roll of magnet wire I could do it with…

Into the final output LP filter I went (the one in the can) to see what I could do with it. The first photo shows the “can” the filter is shielded inside of to keep stray RF at bay.

The second photo shows what is inside of this can. This is also a photo of my completed filter with modifications to make it work on 60 meters. I found that this module had been tampered with once inside. Now to be fair, I did work on this module at one point to repair a broken inductor lead, but that was all. Now, I am getting much more serious while inside of the can…

tentec scout band module low pass filter

I took another measurement with the nanoVNA and decided to remove the inductors and measure them with the LCR meter to see what it said they were. Turns out they were right on spec from the owners manual chart of 2.5uH each. At least that is what it looked like I read on the meter…haha. So I decide to remove an arbitrary number of wraps from each core (3 wraps to be more precise) and take another measurement to see what I had then. The meter showed them at 1.8 to maybe 1.9uH after pulling three wraps off. This put me right in the middle of 80 meters (2.5uH) and 40 meters (1.4uH) about perfectly. So I trimmed off the excess wire, scraped off the enamel so the solder would adhere to the copper and soldered them into the board.

Back to the nanoVNA for another round of measurements to find it still wasn’t where I wanted it to be. The frequency was still pretty low at the roll-off point. I then decided to look at the capacitors to see what they looked like. This is when I noticed that the band module had already been modified somewhat as the center cap was sitting at about 850pf already and not the 1500pf it was supposed to be. I also found that the two shunt capacitors on the ends were also different from the 80 meter module for some reason. I pulled these back to 470pf each and checked it again and now the band pass was in the 6 mhz area, this should be far enough away from the operational band to keep me from having problems so I put it all back together and then checked it into the dummy load.

Success! I am seeing over 120 volts peak to peak coming out of the radio! Woohoo! I couldn’t believe it! I had full power coming out on 60 meters finally! This was a real special moment for me to be honest with you. After this, I reassembled the shielding on the filter network and cleaned up the solder flux and put the module back together.

With all that done, all that is left is to set it up with an antenna and make some contacts with it…

Yeah…about that… There seems to be a major solar storm coming in and has been since the previous day. This is a big deal as you can see from the report. It has shut down radio for most operations. I did call CQ for a while and at one point I heard WY7EE calling CQ but he couldn't hear me. Figures. I did turn up on the RBN so the signal was getting out to some degree in the evening. That was kinda awesome to see as well. I know I have signal going out too as the wattmeter is showing 40 watts forward power. (Remember I de-tune my Scouts to pull some load off the finals since they are getting old and I don’t relish the though of having to replace them for a 10 watt boost in power output) 40 watts will do just as well as 50 from what I have seen in the past… anyway.

The next day we had the storm to start fading out a little and I loaded up the webSDR on my computer and listened for my radio on the Northern Utah listening post. Once the time was late enough, I started hearing my signal on the webSDR! I recorded it and posted it to my YouTube channel as a short if you want to go listen to what I could hear. This is the link.

Link to video about 60 meter signal

Like I said, I am going to revisit the band pass filter for the IF again when I get back into town. I think that can be improved a lot. (my current design is too broad banded in the pass band to make me happy, I want to clean that up some more.) I will write that up when I get the chance to work on it—read Part 4 for the IF filter redesign. Thanks for following along on this little adventure and I hope to hear you on the air at some point. Maybe you will work me on 60 meters with my Scout…maybe…

73 and get out there!

All four parts are here:

- Part 1: Initial Conversion and Filter Design

- Part 2: Crystal Selection and Mixer Circuits

- Part 3: Field Testing and Troubleshooting

- Part 4: IF Filter Redesign (this post)

You can help support this website by using these Amazon Affiliate Links:

QRP/Portable Radios:

Antennas & Tuning:

CW Equipment:

Power & Accessories:

Organization & Transport:

BONUS ITEMS

WK4DS

David

David Saylors 2/7/26 David Saylors 2/7/26

Smith Chart Exploration for Ham Radio: Building Impedance Matching Networks with DIY Inductors

Today finds the unsuspecting ham radio op perusing YouTube for something new to learn as it is really cold outside. He stumbles across a video about using a Smith Chart to match impedance and is intrigued…

What happens next is kinda terrifying…lol

Well to be honest, it is really kinda boring till you see how a smith chart sort of works and you start to learn how to use it to some degree. I have known about them for years, but have never understood how they work or even how to read them.

What happens next is kinda terrifying…lol

As you can see, if you watch this video, (maybe a couple of times), he explains it in simple enough terms that I actually understood what was going on finally! I did come into it with the understanding that the upper half was inductive and the lower half was capacitive from tuning my antennas with the nanoVNA. I would leave the smith chart on out of laziness and simply used the SWR graph to move the null to the operating frequency. But during this time, I started looking at the information presented on the display and noticed at times it would show capacitance and sometimes it would be inductance and also where the marker was sitting. This gave me the clue about what it was sharing with me. That was the extent of my smith chart knowledge though. At least it made sense to me. So the next logical thing to do was to order some smith chart notebooks from Amazon and a drawing compass so I could use said charts. While I was anxiously awaiting the new goodies to arrive, I started binge watching videos on smith chart use and taking away what I could from each video to add to what I already knew. By the time the paper arrived (I know I could have printed them off the web but the notebook format is really nice to be honest) {sarcasm}I was already a “master” at these “simple” charts… haha. {/sarcasm}

I will be honest with you. There is so much about these charts that I still don’t understand that it boggles the mind, but I have figured out how to use them for impedance matching and it is kinda awesome. I actually made the last few pages in my new notebook a cheat sheet based on the above video so I could reference it easily without having to watch the video over and over. I am absolutely going to build one of these fixtures when I get back home too. I would already have done it but I am not able to access my bench to put it together… So what follows is what you do when you don’t have that gear handy.

First things first, I bought a new toy. This is a 200 mhz “scope meter” but this one has another trick it can exploit. This is a actual dual channel oscilloscope AND it also has a arbitrary waveform generator as well! On top of the usual multi-meter functions as well. This thing has a lot to offer…till it doesn’t. It didn’t take long to figure out that the waveform generator doesn’t have the sweep function in it, this would have been nice to play with things. I can’t find FFT modes anywhere in it either so it can’t be a “poor man’s spectrum analyzer”. The little meter does have enough options to be really useful for what I was doing anyway so let’s get started… oh, it doesn’t come in this nice hardshell case. This is an Apache case from Harbor Freight. It is the perfect storage container in my opinion and I am happy to have it trimmed out like this. It didn’t take too long to figure out how to use the oscilloscope and I made a cheat sheet for it too so I can access useful features more easily in the future since a lot of it is hidden in menus due to the diminutive size.

What you see here is pure desperation to see if I can make this smith chart stuff work for me. I am literally about to start making capacitors out of aluminum foil, a sheet of notebook paper and painters tape… Spoiler alert, it worked… You see, in another video I found on YouTube, there was this idea that you don’t need a LCR meter to measure your components as long as you have a known value device, a battery and some ingenuity. I also had a lot of time to play with this concept so here we are… I started by making a really big capacitor to start with to do a proof of concept and to see if there was enough capacitance to make this project work. Turns out there was way more than needed with the initial design, WAY more. So with the proof of concept made from three full size sheets of paper laminated with aluminum foil on one side of each one and then stacked so that the center sheet was one plate and the top and bottom were the opposite plate, I found I had made a .0034uF capacitor! This was more than enough to play with HF radio RF frequencies!!! Woohoo! Now this is all based on me being able to believe my new meter and later I find out that there is 17pf of stray capacitance in my meter and leads. Once I figure this out, and factor it into my math, it is all good but for now with this thing being 3408pf, I don’t think it is really a problem. The cigar box is there to use gravity to apply an even pressure to the “plates” and hold them at a consistent spacing as at this point, these were just three sheets stacked up. The top and bottom are connected to the black lead and the middle one is connected to the red lead. Also tested it with just on plate on the black lead and yep… capacitance went WAY down, so this style of capacitor worked pretty well to be honest. I could make it go up a good bit more by pressing on the cigar box too, I saw 5.0nF at one point while playing with it, that is crazy to me…

I had read somewhere about this idea to be honest. Well a cruder version of it actually. They made an impromptu antenna L network with two sheets of aluminum foil and a sheet of news paper or something like that. That made the capacitor and the inductor was wound on something found commonly in the house in the 1960s or 70s as well. They just used regular old romex house wire to make the inductor and it also worked just fine. Sometimes you just really need to have some “want to” and it can be done. I was a little more superfluous with my build as I didn’t need it to get on the air but rather as an experiment to see what I could learn.I honestly was really surprised to see how much capacitance I could get out of notebook paper and aluminum foil from the grocery store. This tells me that literally anyone that needs an antenna tuner, has one if they want it bad enough. You don’t have to have a Ten Tec 238 to be able to tune that random wire, you just need to gather some stuff you probably already have in the house…

Side note, I also finally acquired a new case for my POTA Scout 555 radio. I still need to finish the pockets for the band modules when I get home, but I now have it in a proper case and not just sitting in a cardboard box in the back of the truck! Also, I made another 60 meter contact today… to the same exact person that I made the first one with a couple weeks back! HAHA! I think we are the only two people on 60 meters CW in the mornings ever…

Here we see what I measured the other day while at a POTA park. What these numbers show is the antenna measurements for the band at the base of the antenna. I literally took the nanoVNA and adapted it to the antenna socket directly to eliminate the 50 ohm feedline from interacting with the measurement. As we will learn soon enough that you can use a piece of feedline (coax in particular) to move the base value around the smith chart should you need the starting point to be somewhere else. But I also learned something else about these starting point numbers below that I will share with you in a little bit.

At the top of the page, right next to the “40m” is what the nanoVNA reported that day at the park. (15.4 ohms and 87.3pf) you have to have two coordinates to plot anything on a chart so these are the two numbers you need to plot your starting point. Ignore the other notes as I am probably wrong on some of it and it actually makes more sense later. But the first thing I had to do was to turn these numbers into the proper numbers that the smith chart uses. This is called normalizing them. You see the chart is relative, you can assign whatever value you want to the center point on the chart and the rest of the chart is “relative” to this value. So if you were to work with 75 ohm coax and wanted to make an impedance matching network to work with it and having minimal losses, then you would assign 75 ohms to the center point. Since we use 50 ohms in almost all amateur radio (if not all) then our value is 50 ohms at the center point.

So here is my 80 meter plot (below) to get to a 50 ohm impedance from where it started at… yes… 1 ohm and 79.7pf capacitive! You see I am designing a matching network to couple my 50 ohm coax to a 18.4 feet tall telescoping vertical with a couple of radials thrown out on the ground. This is not even close to a matching antenna for the 80 meter band at all. Hence the terrible numbers to start with. Well, this was like those jokes you here from high school where you get something simple in the lecture in class about a subject then in the book it might show it with one more complication but the exam shows the Drake equation for the problem on the test! Well this is what happened to me as in the video above, the number in the video was closer to the middle of the lower half of the chart making for a more straight forward solution to the problem. I also did my admittance math wrong too if I am right…lol… since it is all inverted, but this doesn’t matter at this time. What you need to know at this point is that my problem lies outside the unity circle (that is the one I drew on the chart) and I need my “arc of movement” to cross this circle… it does but nearly at the infinity point (on the right side of the chart) which makes the math almost worthless… The reason the math gets pretty inaccurate is the numbers on the chart start getting logarithmic is value and so a small movement on the chart in this area makes huge changes in the values. You want your plot point anywhere else but here, yet this is where I am at in this blog post… haha

Knowing all this, I start this complicated, 3 position move to get me to the center of the chart. Mind you, I think this would actually work, but I am not sure if the math is mathing right at this time. (I am thinking the first move is a piece of transmission line to move the start point around the circle instead of an inductor and the second movement is also not a capacitor either so basically this whole thing is drawn wrong…lol) You will see why in a minute too as to why I dont know. The schematic for this movement is scrawled in the upper left hand corner of the notebook page if you wondered what it would look like to make this circuit. Two inductors and a capacitor to get to 50 ohms… how many antenna tuners have TWO inductors in them? I will help you out here… not many, if any. The number of inductors alone would make this a no go design for the most part unless is was going to be a one band wonder. Just remember I am pretty sure the math on this is wrong, the plot directions are correct, but I am thinking that the suseptance values are needing to be inverted to calculate the impedance for the two movements on the blue lines. Anyway, the point of this blog post is to show what is possible if you want to learn something new and it is not about the math around a smith chart…yet…lol I am diving back into the tutorials to figure out the blue part of the chart next.

After I pulled my hair out for a while…wait, that don’t apply to me…I’m bald already… After getting over the frustration of trying to solve this problem, I redrew it on a fresh page and looked hard at it for a minute and had an epiphany… The plot point is not INSIDE the circle, or even anywhere closer to the middle of the chart at all, which would have been ideal, BUT it is really close to the unity line already. I mean REALLY close, so close in fact, I bet you could simply run around the unity line clockwise to the center point and just “eat” the misalignment on the horizontal resistance line of such a tiny amount and no one would even notice in the real world. You know what this matching network now looks like? A huge by large inductor is what, just a plain ole gigantic coil… Moving clockwise around the impedance lines (the red ones) indicates adding inductance to solve the problem. This is what all the antenna companies use when you buy a mobile 80 meter whip antenna if you think about it, just a huge load coil and nothing more. If you were to zoom in on this, I am guessing the resistive value when you get to the end of the arc, at the horizontal center line (which is the pure resistance line) would be something like 49.2 ohms or something close to that, literally less than 1.1 : 1 SWR maybe less to be honest.

Armed with this knowledge, I wanted to test this theory. So I now needed a way to make a coil to insert between the feedline and the base of the vertical to see if I had learned anything. Well I had this new scope / meter / signal generator widget and I had a way to make a capacitor, I then remembered a video where I guy showed how to measure inductors and capacitors with only a oscilloscope if you have one known device. Well, I have a capacitor that I made and I can measure it with the new meter, so that will give me the “known”.

So I fire up the new meter and plug in the leads and find this. There is no way to “tare” out this number either so you simply have to subtract it from what ever you measure. I figured this would be pretty easy so I just went with it. Below is a photo while I was trimming the capacitor to a size I wanted. I was looking for 100pf and as you can see below on the meter, I was getting close. This is measuring right at 121pf in the photo. I would trim off the edge of the sheet and then check it again, rinse and repeat till it was close to what I wanted.

Once I had my brand spanking new capacitor made and trimmed to size (105pf), I setup a test fixture to do my test with. The test fixture is also expedient since it is all that I had was one of those “BNC to binding post” adapters and just used it as a sort of bread board to attach all the parts to the system. It worked, it was pretty janky, but it worked. All that we have here in reality is a parallel tank circuit. It will resonate at one frequency natively and I can measure that and then use a simple online calculator to see what the inductance is based on my capacitor value and the frequency of the tank circuit. How do I get it to resonate then? Simple, use a battery…

In the other video I had recently watched he showed simply setting the scope to trigger off of a voltage level close to the value of the battery which will allow the scope to capture the ringing of the tank circuit if you pulse it with a battery. I just took a AA out of my pocket flashlight and used it, set the trigger to normal and set the trigger level to about 1 volt and started touching the battery to the two red wires going out to the left in this photo below. This biased the tank circuit (simply applying a dc voltage across the capacitor and charging it) and I was rewarded with what you see below on the scope in the below photo. To be perfectly honest with you, I had done so much wrong in this process that I was honestly surprised that it worked. I even had to show it to Teresa and she had literally zero idea about what she was seeing here, but I had to show SOMEONE that it has actually worked!

The ringing the scope captured is nice and clean and I was able to measure the period of the sine wave at 172 nanoseconds. Transforming the time into a frequency is easy, you simply invert the number or divide 1 by .000000172 and you get 5,813,953 hz. This frequency is not relevant to the ham bands but is only useful in telling us what the value of the inductor is, which is what we want anyway. As you can see from the screen shot below, this inductor is 6.245 uH (micro henrys). I did the plot on the smith chart for 40 meters for this antenna and came up with almost exactly this number, I came up with 6.62uH on the math. This also makes sense as I did this physical coil for the 213” (17.75’) WRC vertical and not this one that is longer that I am using now 221” (18.4’). Another possible reason for the variation from the measured and the plotted values is that my capacitor value could be slightly different from being moved around or being in proximity to metal or some such. You could touch the capacitor with your finger tip and the value would change so this is probably part of the variation…

I made this actual load coil by guessing to be honest, I did use the nanoVNA as a SWR meter when I made it and I would take off a coil or two and measure it and I simply walked the null in on the antenna for 40 meters that day. Now I know how to use a smith chart to do that math ahead of time. That is pretty cool.

Literally using trash to resonate as a tank circuit is kinda cool to be honest with you. The wires for the capacitor are simply taped to the aluminum foil, nothing more as I didn’t have a way to solder them together or anything like that. This was truly a temporary test fixture for experimentation.

The next logical step was to make an inductor for 60 meters and to hook it up to the antenna and measure it with the nanoVNA to see how close I could get it. This is where things started to go south…

First of all, I had problems replicating the same resistance and capacitance from that day at the POTA park. The photo of the VNA above shows what I am talking about. Now it is 1 ohm… yeah basically a dead short for the RF. But more importantly it is different from the day of my test which was about 10 ohms (if memory serves me) but basically this doesn’t matter when you get to the region of the smith chart that this plot is landing in. The capacitance is what really drives this position between these two numbers and it was virtually the same. The amount of inductance will be more for 1 ohm but not a whole lot more.

Well what happened when I hooked up the coil and the vertical and stuff in the driveway was a whole bunch of nothing! It just made a circle around the outside of the smith chart, which is bad if you don’t know. You want your line to go through the center of the chart at the frequency you want to use and if it goes around the outside it ain’t going through the middle!

Deflated that I had probably done all that math wrong…again… I was about to throw in the towel when the wind blew and the plot on the nanoVNA moved towards the center! What just happened??? I start messing with this and that, as you can see in the photo above that the coil output wire is just poked into the coax port on the antenna. This has to be the worst way to make this connection, but if this is all you have, then this is what you do…

I could grab the vertical and that would make drastic changes to the smith plot, so I thought about moving the antenna without touching it and I found a roll of electrical tape and used that to tug on the vertical as it is in a QD mount (which is not a great connection to be honest that I have found). I even cleaned some stuff to no avail, but when I put the tape on the antenna and pulled it in certain directions, I would get the plot you see below. Notice the marker is at 5.340 mhz and at 55.2 ohms and just 1.49nf capacitive. This is less than 1.2 : 1 SWR and I am sure that it is off a little because of the system losses at this point. All the loose and dirty connections along with the random radial placement (I find this makes a pretty large difference with my systems) made getting repeatable results almost impossible. This told me that the coil worked though and that my math was not wrong! I had actually learned something here!

Once I figured this out and took a couple of photos for the blog, I tore the system back down and put it all away so I could get started on this write up about it. This has been an amazing process to do this and I learned way more than just how to do impedance matching with a smith chart. I learned that my system is way too inconsistent to simply make a coil and expect it to work in the system. If I had all the parts hard mounted in place with corrosion inhibiting paste on the connections then I could calculate this coil and it would drop right in. I was blown away by this and cant wait to find another use for my smith chart notebook. I hope this has helped you in some way either by simple entertainment or by learning something about smith charts and antennas, or maybe that there are YouTube videos about how to do this sort of stuff, either way, thank you for reading to here and I hope you come back for more of my ramblings in the future!

You can help support this website by using these Amazon Affiliate Links:

QRP/Portable Radios:

Antennas & Tuning:

CW Equipment:

Power & Accessories:

Organization & Transport:

BONUS ITEMS

WK4DS - David

David Saylors 1/15/26 David Saylors 1/15/26

Converting Ten-Tec Scout 555 to 60 Meters: Complete Band Module Modification Guide [Part 1]

When I first decided I wanted to make a band module for the Ten Tec Scout 555 that was able to get on 60 meters, I had no idea what really was involved.

A little backstory here is kinda needed, you see the Ten Tec Scout 555 has become one of my favorite radios for POTA operations and I even find myself setting one up in the shack to tinker with from time to time. I own 3 Scouts and 2 Argos at the time of this writing if that tells you anything. I don’t know if it is the simple elegance of the radio or the fact that it can operate on almost all of the HF bands in such a small form factor, but I love it. Well there are a few things for sure that draw me to this radio like the fact that these radios have the now infamous Ten Tec full QSK (full break in) keying. This keying works flawlessly too by the way. Another reason for such love for these radios is the amazing receive they have even for such a compromise design. With headphones (or even those little earbuds), it is pretty easy to hear stations in the edge of the noise floor and make contact with them.

Well, if you noticed I said… almost… all the HF bands… This is because we have been granted, by the IARU, some space in the 60 meter band as secondary users.

Some of this band space is open to use with power levels up to 100 watts too. (There has been a recent change that modifies the allocation to allow a bandwidth section that is non-channelized but limits the power to 9.5 watts ERP so play in this area carefully. Basically this new region is a QRP only region for now.) Aside from that though, the Ten Tec Scout 555 can operate quite legally in the other 4 sections… or it could if… there was a 60 meter band module… You see this 60 meter band allocation happened after the Scout 555 production run had ended, so Ten Tec never made a factory band module for the 60 meter band that I am aware of.

I started this journey by digging through the owners manual for the Scout as Ten Tec always shipped complete schematic diagrams with their radios. Sometimes there would be missing insignificant data, but you could trouble shoot the radio just fine with them. Once the radio diagrams were located, I started looking at how the band modules made it change bands.This turned out to really be quite simple but I was missing one or two critical values. You see the Ten Tec Scout 555 band modules have a crystal in them and the frequency on the crystal didn’t make sense…at first.

tentec scout 555 band module if mixer board

Above is the schematic and a photo of the board that goes with it showing the crystal that I couldn’t understand. This is what tells the radio what band it is on. Looks pretty straight forward at a glance, doesn’t it? Well look at that XTAL value at the end of the chart for 80 meters. Yeah, it takes a 7.444 mhz XTAL to get to the 80 meter band. So I figure the PTO is something like 3.0 mhz so it can get the first negative harmonic when mixed or something like that…nope…turns out I was totally wrong…

tentec band module low pass filter circuit

This is the other half of the band module. A classic low pass LC filter and that’s all. This is the output filter that the 50 power amp sends the RF to before it goes to the antenna. Below is what this part of the module looks like. These inductors and capacitors are shielded as they are delivering and filtering considerable power and could interfere with the small voltage levels on the other board that sits right beside it if they were not in the “can” or otherwise known as a ground shield. I don’t know why there is a hole in the shielding either as there is no adjustable parts inside the “can”. I chose this particular 80 meter band module for another reason as well. I have been inside this filter circuit before. When I acquired this module, the fellow I got it from told me it was dead and gave it to me. Turned out to be a broken lead on one of the inductors in this can. It took me a while to desolder this monstrosity to be able to access the parts inside of it. But persistence paid off as I was able to get it repaired and back in operation. I took a lead cut from a transistor and soldered it to the wire on the inductor and simply re-soldered it to the board and it came right back to life. So if you have a module that just stops transmitting all together, I recommend you pull the lid here and look at the inductors to see if one is broken free from the board, that might be all that is wrong with it. I also hot glued the toroids in place to help prevent this from happening again. Anyway, back to the project at hand…

tentec scout 555 band module low pass filter board

I also looked inside several band modules to see what the differences were and I found some interesting things when I did. For starters, the 10 and 12 meter band modules both use the same circuit boards. They just leave out the second crystal and the switch parts for the second crystal and put a crystal in it for the 12 meter band only when configured for 12 meters. I guess, to be fair, I should have also figured out how the PTO worked as well then I could have figured out the reason for the odd crystal values, but here we are…

Another thing I found was that the engineers at Ten Tec used whatever circuit board blanks that they had on hand to build the band modules apparently. I say this because I found 10m circuit boards (the ones meant for two crystals and the switch) fleshed out with parts to make them into 40 m band modules. (Like the one in the photo above) They apparently just used whichever ones they had on hand at the time. Needless to say, what I thought was going to be simple was starting to turn into a pretty major endeavor.

You see it was starting to look pretty daunting since I didn’t understand what the reason for the odd frequency crystal was and that there were 4 tuned filters in each band module. Also the crystal value just didn’t make sense on the surface. The values were all over the place. I was about to throw in the towel calling it just too complicated, even though the parts count in a band module is really low…till I found two things. One was I looked up what the “555 timer” on the board actually was (Here is a hint, it aint no timer) and the other was NA5N’s website.

Excerpt from NA5N’s website showing the level of detail these drawings contain.

NA5N’s Scout 555 page is a figurative gold mine of information with just plain cash money piled on top of it, (just to drive this point home take a look at the piece above I grabbed for reference). I can not thank him enough for this information as without it I would not have been able to get this project working as quickly as I did. He also has some really interesting mods he has done to his own radio as well. If you want to perform his mods on your Scout, he gives you detailed information on what is done and literally how to do it…step by step almost. The greatest part of his page though is his info graphics he has built and placed there. These graphics show all sorts of information that the radio schematics leave out.

This and MUCH more is available on the NA5N website.

Things like the frequency path (pictured above) through the radio in a chart so you can understand how the engineers at Ten Tec arrived at each band frequency with these plug in modules and a PTO. Complete with oscilloscope test point and what you should be seeing at these points! Like I said, a gold mine buried in cash money…

Based on his chart I went through the band module and looked at the filters for the various circuits and decided (more like assumed based on the values of the parts) that I could simply re-tune an 80 meter module and “push” it up to 5.3305 mhz easily enough and without too much fuss…nothing could have been further from the truth.

So I start tinkering with the filters and piping them through the nanoVNA into the s21 input so I can see the filter shape and all is well from what I can see. Turns out the low pass 80 meter band module filter cut off frequency was about 5.5 mhz or so to start the rolloff so the 60 meter band was still in the pass band! One down three to go! Next I figured out that the PTO is the same for every module since it is part of the radio and not in any of the modules so that filter also didn’t need any mods. This left two filters to re-tune, just so happens it is the two with the adjustable inductors in them. So I start with the LO BPF (Local Oscillator Band Pass Filter) that filters the signal passing through the radio from the antenna. Why they call it the same thing as the LO BPF that is in the output of the mixer chip is beyond me, but here we are… This didn’t go well as I was not able to get enough adjustment out of the inductor slugs to get the passband up to 5.350 mhz, shoot I couldn’t get it to tune up past 4.5mhz if memory serves me. It was far enough that I couldn’t get it work so I looked at what I had and decided to wind some air-core inductors to a lower value and see what I could do like that.

Well, to be honest, I don’t know how I was so successful here. Maybe it was the sheer audacity in the fact that I was woefully unskilled in building filters for HF or the mind boggling lack of knowledge of how filters work and how to make them, but I got it almost perfect on the first try! I made a couple different inductors by winding magnet wire on a 1/4-28 bolt (that’s a little over a 6mm bolt for the rest of the world) and the threads made getting good tight coil layers easy. I borrowed my friend’s LCR meter and measured them and blissfully declared them good to go at 2.0uH each. Did I mention this is a budget LCR meter and I have no way of knowing what the level of calibration is for this part of the meter? I also learned later that I can measure my inductors with a signal generator and a oscilloscope. Guess who now owns a signal generator as well as an oscilloscope...

Once wound and “measured” in the board they went! I then tinkered with the capacitors till the pass-band looked close to what I thought it should look like. (I had also learned from the wonderful world of youtube that I should see less than 1dB of loss in the pass-band and the 3dB cutoff point is where the filter technically is measured..typically.) As I mention in a bit, I used the wrong kind of capacitors (the little blue ones) to start with, although the module did work like this, I updated it with NPO capacitors ultimately as well.

circuit board tentec scout 555 band module

I went down a long path of learning on this project, if you haven’t already noticed from the inserted comments in the story. I have very little formal training in Electrical Engineering, you see I went to a two year trade school back in the 1980s and basically got the “intro to electronics” that EE’s would get before learning things like matching the impedance of the filter to the next stage and to use temperature stabilized capacitors in RF filters so they don’t move the pass-band around when they get warm. NPO capacitors have become my best friends here…lol. A hint for my peeps who also didn’t study RF in college, look at the circuit board above that has the crystal on it. You will see the little capacitors on that board and some have little painted tops on them. This indicates NPO capacitors when the letter designation will not fit. I have now purchased a lifetime supply of these caps off of eBay…haha.

Anyway, now the pre-amp band-pass filter was functioning like it should. One to go…

Tune in for part two where we get into the problems I had to solve to get this module working and how well it works now that I have figured out my mistakes.

Continue reading the series:

- Part 1: Initial Conversion and Filter Design

- Part 2: Crystal Selection and Mixer Circuits

- Part 3: Field Testing and Troubleshooting

- Part 4: IF Filter Redesign (this post)

You can help support this website by using these Amazon Affiliate Links:

QRP/Portable Radios:

Antennas & Tuning:

CW Equipment:

Power & Accessories:

Organization & Transport:

BONUS ITEMS

WK4DS - David

David Saylors 12/11/24 David Saylors 12/11/24

sBitx V2/V3 CW Problems: Why I Switched to Ten-Tec and Penntek for POTA Operations

When I first got this radio, I found it had some keying problems on CW but I just adapted to them and used it anyway. These problems are in how the software monitors the CW circuit and keys the radio and such. Turns out that as the radio heats up, the problem tends to get worse causing me to have to slow down the keyer to be able to send accurate code. Even with these tactics, I still send many mistakes towards the end of an activation due to the lag in the keyer.

I have an interesting relationship with this radio…

The reason I currently dont use it for SSB is the audio is terrible and I need to trouble shoot that on the bench to see what is going on there. At first it had a weak microphone element so I made a preamp to correct for this but it still doesn’t seem to work all thatwell. Based on all this, I have not used SSB. (I do plan to revisit the SSB circuit to see if I can get it right)

As I also own several portable Ten Tec and Penntek radios that work wonderfully for SSB and CW, I threw in the towel and just started carrying one of those as well as the sBitx. It doesn’t take long to change out the radios since they are so small and light and I really like the break in on Ten Tec radios (the Penntek has wonderful break in too). Another huge plus is that the filtering on the Ten Tec radios is much better than the sbitx in my opinion. Now to be fair, the sBitx filtering is good, but the Ten Tec radios are just better. The Penntek TR-35 suffers the same problems that the sBitx suffers from. Strong, nearby stations will dull the receiver sensitivity.

What I have found that helps in the scenarios is to simply move. There is nothing an overloaded front end can do to help this problem. I do like the features that are available in CW on the sBitx though. Things like the memories and how easy they are to employ is awesome. Another thing is the waterfall is real nice that runs right alongside the CW decoder which has helped me a couple of times. I dont watch the decoder much, but it is nice to be able to see it match what I copied at times for call signs and such. Another great thing about the sBitx is the touchscreen. Not needing buttons is real nice. The only part of the experience that is honestly lacking in CW is the keying problem. Once someone solves this problem, this will be a game changer for a radio. I am still experimenting with different cooling solutions to keep the machine cooler to see if I can get the keyer to work better.

As you can see, this machine makes for a great FT8 field radio. The lack of a need for an external computer is a huge benefit when it comes to this. I just wished the dev team could sort of the CW keying problem this radio has that makes it less than ideal for this application at this time. One thing I plan to do soon is to set it up and see how running QRP power only helps alleviate the heat problem by not running 20 watts on 15 meters and building up the extra heat. This may solve most of my problems but the radio is designed for more transmitter power so I want to access that power.. Another option is to use a keyboard to send the code as it generates the code internally in software instead of polling the IO architecture to get the keying input. This is fun to me too but a nice key is also fun to use. So till the dev team does come up with a solve for the CW keying problem, I will relegate this radio to keyboard CW and FT8 (and maybe even SSB once I address the audio problem again)… But the main reason I wanted the radio to start with was the built in FT8 function that it has, so in that regard I have a great radio that I love to deploy!

If you are considering getting one of these radios, just be aware that it is far from perfect and it is literally made for experimentation. As long as you keep your expectations in reasonable bounds, this radio can be a lot of fun.

You can help support this website by using these Amazon Affiliate Links:

QRP/Portable Radios:

Antennas & Tuning:

CW Equipment:

Power & Accessories:

Organization & Transport:

BONUS ITEMS

David Saylors 12/4/24 David Saylors 12/4/24

Multi-Band POTA Strategy: Ten-Tec Scout 555 + sBitx FT8 on 15m/17m/20m/40m

The location is all too familiar, but I set out to do a sort of special operation today. I wanted to complete a POTA activation using two radios, 3 modes and 4 bands in one sitting. This doesn’t sound like a tall order but since I am operating inside the truck cab, this does involve a little logistics to not just have stuff piled everywhere while I am operating. As you will see in the photos below, I still ran into this problem somewhat, but it was manageable.

Today was a fun day…

I setup at the disc golf parking lot again, but this time there were quite a few people there and some of them actually quizzed me about what I was doing. One gentleman, Jerry as noted in my log, actually chatted for a good bit about how he has been looking to get into ham radio but the Atlanta area is kinda tough on locating local hams for some reason. I gave him a card and told him to email me and I would give him as much info on it as I could find to get him on the right path…

As you can see in the photos, I set up ham sticks and this time I started on 40 meters FT8. I wanted to get the FT8 portion of my “sprint” if sorts out of the way first as the other two modes were going to be on the Ten Tec Scout 555. I had recently activated with it and it was acting up with chirping on CW and reports of RF noise on my audio on SSB. I attributed this to poor connection of the 20 meter band module as it was fine on 15 meters. Armed with this knowledge, before I left out for the park, I took the radio to the shop and use the Deoxit for gold contacts and a tooth brush to clean the contacts on the band modules. I even wetted one module pretty good and used it to “clean the contacts in the radio by plugging and unplgging the module a bunch of times.

This improvised procedure worked as I got good reports and the CW ran flawlessly as you will see later. Deoxit is magical stuff, if you dont have any, it is work your investment to grab a small can of it.

I really enjoy using this radio for my FT8 operating and with the upgraded finals and RF deck, it runs flawlessly now with SWRs in the 2:1 and even slightly higher range without problem. Today saw SWR levels on transmit of about 1.7:1 and it happily skipped right along making several contacts in a row at one point.

After completing 6 QSOs on FT8 I figured it was time to get the Ten Tec Scout 555 out of the case and see what I could scare up on CW.

The 40m Ham stick that I have must have a really high Q as it is very narrow banded. So I have it tuned for the CW portion of the band and the SWR in the SSB area can be quite bad at times. For this reason, I chose not to hunt any SSB contacts on 40 meters today. Once on CW (this was about 1/2 hour later as this is when I talked to Jerry) the band must have been closing or the band noise was getting so bad that I could not hear many stations. I was able to work Alabama and Tennessee before the call signs faded into the noise. That is something you will learn pretty quick about HF radio propagation, if you want to work closer in stations, use the lower bands, but if you want to reach the west coast from Georgia on a ham stick, use the higher bands like 15 and 20 meters. When 10 meters is open I have worked other continents with ease… Don’t discount those higher bands, they are truly magical.

In the above photo I have the CW key and keyer staged but not connected. The mouse is actually driving the FT8 machine and makes working FT8 so much easier to be honest.

In these two photos you can see what you have to work on constantly. The above photo shows the cable that came with my Ten Tec Scout 555 when I bought it. This is a common issue you will find with home shop made cables. These were stripped back way too far and as I used the cable, the conductors started breaking and I was beginning to worry about blowing fuses.

I happen to own a tool that is designed to remove these pins from the connector, so I am able to dismantle this connector properly. I dismantled it, then took it apart and cleaned it up, properly stripped and re-soldered the pins, then put heat shrink tubing on it all to insulated and protect it better. Now I am not so worried about it either shorting and melting the wire or blowing the fuses and shutting down the activation over something as simple as a cable…

Once I finished on 40 meters and had two modes in the bag on one band, I switched over to 15 meters CW to see what was happening there. There was a contest going on so it was a little crowded and I didn’t understand the exchange so I didn’t jump into the contest, but rather setup on a clear spot and calledCQ and worked a couple of stations there, one station of which is DX!!!

At this point. I got a phone call from KG4WBI about a completely unrelated matter, which we discussed and I told him to fire up his HF rig and we would see if ground wave would make the trip to his house from the park so I could get Georgia in the log as well as a 2nd mode on 15 meters! Well, it worked just fine and we had a great QSO on 15 meters SSB before he had to sign off and go run errands. So having confidence that SSB was going to work better I started calling CQ on SSB.

I got literally zero replies to my calls… so I went hunting instead. I found two more ops that could hear me and I was able to bag a couple more QSOs and these were Park to Park contacts to boot!

These three photo show me installing the band module into the Ten Tec Scout 555 transceiver. It really is that simple to change bands on this radio. Now to be fair, this is not as simple as just turning a knob, but it really isn’t that bad.

To remove the module you pull out the bottom of the little lever on the front of the module and it will pop out enough to be able to slip it out, then you grab a different one off of the pile and stick it back in the slot in the radio. Push it to seat it and then your ready to go.

At this point, I switched over to 20 meters and since the PTO (notice it is not a VFO) was still up in the SSB area, I decided to see if I could hunt some contacts with that mode. I landed one contact in SSB on 20 meters and was happy to get them in the log.

After working the one lonely SSB contact on 20 meters, I decided to give CW a try as well… Remember me mentioning a contest? Well, it was here too. It was going strong as well and because of this I was only able to work one contact on CW as well. If nothing else it netted me another band!

My last stop of the day was 17 meters. The 17 meter band is a WARC band and therefore it is off limits to contesting. Now, to be fair, POTA has been called contesting of sorts, but as of right now it is not considered a contest but is more in the spirit of something similar to a rare DX station activating on the same band and developing a huge pileup there. So I proceeded to hunt me an empty spot (18.078mhz) and started calling CQ.

This is when things literally took off! I netted a whole page of contacts in about a 1/2 hour span of time! What a day! 4th band in the books and I was stoked!!! 17 meters must have been where all the POTA ops had went due to the contest and I didn’t get the memo…lol. The Scout worked flawlessly after the cleaning and I cant be happier now with the old girl.

One of the great things about 17 meters is the propagation is really anybodys call. I worked Hungary at one point as well as California, Alaska and Idaho, then there is a ton of east coast stations too, it was everywhere today on 17 meters. Ham radio is so cool…

Before closing today I wanted to mention that Aaron KV9L and I have a youtube channel and we just hit 2000 subscribers (as of this writing)! If you are into ham radio and watching videos about it, then we would love for you to come over! I am currently doing a series of short form videos that are teaching CW one letter per day. There is no limit to the number ofd times you can watch them so I am hoping these become long term training aids for people.

Once I get the letters, numbers and punctuation done, I am going to start doing words next. After words will come sentences so we will see how it goes. Anyway, I just wanted to thank the 2000 people that made us as successful as we are!

You can help support this website by using these Amazon Affiliate Links:

QRP/Portable Radios:

Antennas & Tuning:

CW Equipment:

Power & Accessories:

Organization & Transport:

BONUS ITEMS

David -WK4DS

David Saylors 11/27/24 David Saylors 11/27/24

Ten-Tec Scout 555 POTA: 74 CW Contacts at Raccoon Creek WMA [US-9875]

As you can see from the QSO map above, the bands were alive and well on this day from Raccoon Creek WMA (US-9875). The calls just kept coming in and I finally had to got QRT, with people still calling, and pack up as I had to meet the wife for a dinner date! I normally clear the little pile up I will draw in and then I can simply power down. I really felt bad about having to shut down with stations still calling me. I now know what those rare DX station feel like… It is surreal to experience that to be honest… especially from Alabama.

Today got so fast paced that I forgot how to do CW properly! Let me explain…

You see, today I activated US-9875 Raccoon Creek WMA and I went at a different time of day. I wanted to spend several hours here today as I dont get over to the area often and I wanted to try to get as many contacts as I could in the afternoon. My goal was 60 QSOs today which is way more than I usually worry about, but like I said, this park is a solid 40 minutes in one direction and I dont go this way too often so I wanted to “make it count” if you know what i mean.

I rolled into the WMA at about 14:30 local time and set out to build the radio down by the Tennessee river. This is a small parking lot at the end of one of the gravel roads into the WMA and a lot of locals come to this spot to fish in the river from the shore. Did I mention it started raining right after I got the antenna setup and I got into the truck? Well, let me tell you, the rain set in and it didnt stop the whole time. I even broke down the antenna and stuff out in the rain today!!!

The above photo shows what the station looks like right before I plug all that stuff in and turn the power on. Everything I need to get on the air is in that pile for both SSB as well as CW. To be fair, I can get by without the Picokeyer and the 1/8 mono to 1/8 mono cable and I could simple plug the paddle right into the radio and it would work just fine. So there is really excess here above what is absolutely needed.

I did get the nanoVNA out and look at the antenna to make sure the rain didn’t do something to it like push it out of band due to the conductivity of the wet earth or what ever. Turns out it was just fine… It was a little low with the water on everything but the null was really close to the bottom of the 15 meter band edge so I used it and didnt worry about it. If you will notice, it was only 1.233:1 SWR at the band edge so it was plenty happy and we never checked it again after this on 15 meters. When I switched to 20 meters, the SWR had moved up to about 1.8:1 or maybe it was at 2:1 but I ran it and as you can see in the log, that didn’t seem to matter at all.

I setup shop on 15 meters SSB for a change and wanted to see what I could get before 15 faded out, but I noticed almost immediately that the ALC light wasn’t coming on at all when I would transmit audio. This lamp should just blink on the energy peaks but it wasn’t coming on at all. I messed with the mic gain and nothing. I did notice that I could wiggle the cord at the plug and it would make all sorts of stuff happen. This pointed me to the connector being faulty somehow but workable to some degree.

I made a few contacts with it like this and basically yelling at the radio would barely get the ALC to illuminate. I asked the last person for a report and they told me the audio was muffled and weak. Armed with all this knowledge, I decided to open the connector and see if a wire was broken. Well, they were not broken…but they were also not connected either. There were two cold solder joints from the factory…figures. I got a pretty decent photo of the green wire in the below photo. Well…that shuts down the SSB portion of this activation so onto 15 meters CW!

The 15 meter band has two things that make it unique. It is quieter than the lower bands for me and the “skip distance” is MUCH further with mobile, or improvised antennas. I didn’t make many CW contacts on 15 but check out the locations! Washington state is pretty common for me on 15 meters, in fact the entirety of the western United States is easier for me to work on 15 meters during the day. But a lot of people apparently don’t know this so lots of times the band will be open but there wont be anyone on it. Case in point today, I worked 4 ops in 11 minutes of calling CQ.

After vacuuming the bands of CW ops, I moved to FT8 to see what was happening and this is my “yardstick” of how open the band is. Turns out it was REALLY open! 15 meters FT8 netted a nice dozen contacts and got me almost half way to my original goal of 60 QSOs! This didn’t take long either and just goes to show that the higher bands are great if you will just go check them.

I had switched radios to use the sBitx V4 (I did the software upgrade and got some new features like the color coding of FT8 information you see below) You can also see that I was transmitting with 17 watts too. This is not precise, but it is close and I use it for my logbook notes.

After finishing on 15 meters I moved down to 20 meters to finish out the day. The sun was starting to set at this point and I knew 20 meters would serve me better at this point. after hunting W9XT, I set up shop on a clear frequency and started calling CQ, this is when things got a little crazy. I had a nice little pileup form pretty quick that took me about half an hour to clear, then nothing… It must be band fading at this point as the stations just vanished. I figured I would switch over to FT8 for a few minutes at this point too and see what I could get in that mode. I didn’t mention that I used the sBitx for CW at this point and to be honest, I dont think I will use it for CW seriously till there is a software change to make it work better. If you try to use it much past 18WPM it is like it fights you and induces mistakes for some reason. The people smarter than me in the email reflector seem to think is has to do with how the software scans the inputs on the radio, but I do know it will induce mistakes in your sending if you are not very attentive and send a very specific way. It will work if your careful and go about 18WPM max. I can use a keyboard to send CW but that really isnt all that much fun to be honest.

I struggled with FT8 today on 20 meters for some reason. The QSO could not complete to the 73 so it would not autolog the QSO. It would also not finish the exchange many times either. I could get it to send the signal report then they would send back and they would just get stuck in that step and never move past it. It got really frustrating towards the end, but I did manage to net some contacts here too.

At this point I had made 48 contacts which is a phenomenal day out for me, but I wanted 12 more to have that 60 that I started out my goal with! So at this point I move back down into the CW portion but this time on the Ten Tec Scout 555 instead since the CW mode on it works beautifully.

It took me a couple minutes to switch the radios out and to find a clear frequency and get started, but once I did, it didn’t take long to get a HUGE PILE UP going!!!! I got so excited during this part that I was racing the clock to see how many I could work before having to shut down the radio and go home as I was almost out of time. I started rushing the closing and it was here that I got sloppy with my CW. You see, I normally use QRP power levels for the most part, just the sBitx and the Ten Tec Scout are QRO by the rules and the sBitx is borderline to me. I will usually turn the power down to 5 watts or so anyway to preserve the finals in the radio but today I had the Scout and it is set at 50 watts and is not easily field adjusted from that power level.

As the pile up raged on, I got so lost in the process that I started sending 72 intermingled with contacts getting 73 instead and finally someone stopped me and asked why I am signing both modes and this is when it hit me. I had been running on autopilot about half the time just logging contacts and the muscle memory would just send the 72 and I would not even think about it. I would then called QRZ and get another call, rinse and repeat… Here is the next problem for me. My ragchew copy and my POTA copy are very different levels. He sent me the message at the speed I was working POTA contacts. Your brain will learn how to copy the formatted style exchanges without even thinking about it. I know that I am going to get a two letter state after the signal report and I can copy callsigns really well for some reason up to about 25 WPM, but send me a full sentence question and it breaks my brain. I cant copy half of it without writing it down. I can ragchew comfortably at 18 WPM max at this time, but if you ask me a question about my radio or something that isn’t part of the usual banter in a POTA contact and I am lost… I apologized for this mistake I had been making for probably 20 minutes without even realizing it and it was really close to when I had to leave anyway so I went ahead and called QRT to get the radio put away as it was raining really well at this point too…

To everyone that reads this that I didn’t get to work on this day, I am sorry to have to had shut down the rig and leave, I was having a wonderful time and wanted to stay longer!!!

The moral of this part of the story is dont get in such a hurry that you cause confusion with the hunters, take your time and be sure in what you are actually sending out over the airwaves.

On a brighter note, I got my 60! and 14 more!!! I dont know how long it has been since I got that many calls in the log in one day. Until next time I hope to work you on the air!

Read more Ten-Tec Scout 555 POTA activations:

- [Another Scout 555 POTA post]

- [60m band module series]

You can help support this website by using these Amazon Affiliate Links:

QRP/Portable Radios:

Antennas & Tuning:

CW Equipment:

Power & Accessories:

Organization & Transport:

BONUS ITEMS

WK4DS - David

David Saylors 11/13/24 David Saylors 11/13/24

Go bag POTA!

The idea behind building a POTA go bag is simple. You want everything you need in one place, ready to grab and go. No hunting for coax in the garage, no trying to remember which box has the paddle, no scrambling to charge batteries. Just grab the bag, throw it in the truck, and you're ready for a park activation. Or an emergency. That's the whole point!

Why Build a POTA Go Bag?

Today was about testing my emergency / travel radio kit to see how it actually performs in the field at Eagle's Nest (US-0716). Spoiler: it works better than I expected, even with some equipment drama along the way.

QRP Guys power SWR dummy load meter with Penntek TR-35 and POTA go bag gear for field testing — The QRP Guys SWR meter checking the Reliance Antennas 40m EFHW before starting the activation. I wanted to make sure the SWR was acceptable before putting power through it.

Complete Gear Walkthrough: Everything in the Bag

Here's every single item in my POTA go bag with approximate costs. This is everything you need for a complete field station that fits in one bag:

Radio and Accessories:

Penntek TR-35 QRP transceiver: N/A (no longer available… sad radio sounds…)
Xiegu G90 HF Radio Transceiver: 465$ (A great Alternative but not quite as small)
N6ARA CW paddle with case: ~$70
Headphones in ziplock bag: ~$20 (any decent pair works)
QRP Guys SWR meter: ~$20 (for field checks)

Power:

10-cell AA battery holder from Amazon: ~$12
10 rechargeable AA batteries (Eneloop or similar): ~$25
Power cord with Anderson Powerpoles: ~$10

Antenna System:

Reliance Antennas 40m EFHW: ~$60
ABR Industries coax with ferrite choke: ~$70
Backup coax (generic RG-8X): ~$30
Arborist throw line (40 feet): ~$8
Throw weight (1" nut from machine shop): Free!

Accessories:

Nylon tool bag from Amazon: ~$25
Small notebook for logging: ~$3
Pen (main) and pencil (backup): ~$5
Ziplock bags for organization: ~$2

Total Kit Cost: Approximately $825

Now, I know that seems like a lot upfront, but remember this includes the $465 radio. If you already have a QRP rig, you're looking at about $350 for everything else. And this entire kit lives in one bag ready to deploy. No hunting for gear, no forgetting critical pieces. That's worth something!

The beauty of this setup is that it's modular. Start with the basics (radio, antenna, power) and add the nice-to-haves over time. I didn't buy everything at once. I built this kit over about six months as I figured out what I actually needed in the field.

I did the entire activation from Eagle’s Nest in US-0716 with just the “kit” radio that I have put together. I have the QRP Guys SWR meter in the photo here as well (it is in the clear plastic case), but this is because I wanted to check the 40m Endfed Halfwave Antenna from Reliance Antennas to make sure the SWR was ok. He cuts them long so you can tune them once in the field and I have not cut mine yet.

You might be wondering, why go through the trouble of building a dedicated go bag instead of just grabbing gear as needed? Fair question! Here's my thinking:

For POTA operations: Having everything organized in one bag means I can decide to do an activation on a whim. If it's a nice day and I have two free hours, I don't need to spend 30 minutes gathering equipment. Grab the bag, drive to a park, and I'm on the air. This makes POTA way more accessible and way more fun.

For emergency communications: This is the real reason I built it this way. If there's ever a real emergency where I need to set up communications quickly (hurricane, power outage, whatever), I don't want to be hunting through the garage for my radio gear. The go bag concept means I can grab it and have a complete, tested, working field station ready to deploy immediately.

For travel: The bag is small enough to throw in the car for road trips or to check as luggage on a flight. Having everything self-contained makes it easy to operate from anywhere. I don't need to bring my whole shack, just this one bag.

The mindset shift: Building a go bag forces you to think about what you actually need versus what's nice to have. Every item has to justify its space in the bag. This makes you focus on core functionality rather than bringing every gadget you own. It's a good exercise!

The result is a system that's ready when you are, tested and proven in the field, with no excuses for not getting on the air.

POTA go bag opened showing Penntek TR-35 QRP radio 40m EFHW antenna power cord Anderson Powerpoles — One side of the bag showing the Penntek TR-35, the 40m EFHW antenna, power cord with Anderson Powerpoles, and the throw line with weight. Everything organized and ready to deploy.

The Penntek TR-35: Heart of the Go Bag

This particular nylon bag came from Amazon and has two main sides that unzip and lay flat. Inside each side are additional pockets to hold small, thin items as well. I have organized mine to hold the Penntek TR-35 and all the stuff needed to deploy it in the field. Literally everything. Let’s go for a short “walk” through this bag.

In the above photo is the radio, antenna and a power cord with Anderson Powerpoles installed. I also have the battery pack in the zippered pocket (more on that later). As well as a rope and weight for throwing a line up into a tree to haul up the wire antenna with. I just wound off about 40’ or so of arborist throw line for this kit and I have included a huge 1'“ nut from the machine shop for a throw weight, which works perfectly…

The other side contains the coax for the antenna and this is the only thing that I have two of in the kit. Coax has let me down more than once while out at parks so I now carry backup coax. No matter how careful you are with this stuff, it will fail on you. It just ins’t designed for all that movement and eventually you will break the center conductor. This is also why I check my system with the nanoVNA before starting…except today where I used the little SWR meter instead. One of the coaxial cables is the gold colored one made by ABR Industries and it has the ferrite common mode choke built into it. This is really wonderful coax and I wished I had learned how important quality coax was a long time ago…it makes a huge difference.

Also in view in the below photo is the N6ARA CW key in the little storage box it comes in and the headphones are in a ziplock bag to keep dust and dirt out of them. Nestled into the pocket behind the coax is a small notebook for logging. I also have a pen (my preferred tool for logging as I can see it easier than pencil) and a pencil since a pencil never runs dry, it is my long term back up to me pen…lol. I dont really trust pens either…haha.

POTA go bag coax cables N6ARA CW key headphones logging notebook pen pencil field accessories — The other side holds coax (including backup coax, because it will fail on you eventually), the N6ARA CW key in its case, headphones in a ziplock bag, and a notebook with pen and pencil for logging.

N6ARA CW paddle in storage case with headphones ziplock bag field logging notebook POTA activation — The N6ARA CW key comes in this little storage box which fits perfectly in the bag. Headphones stay clean in a ziplock, and the notebook/pen/pencil combo is my preferred logging method in the field.

So here is the station assembled and under power. You would be surprised at how long this radio will run on those AA batteries too. It is really shocking to me how well this little system works. I have yet to have the batteries die during an activation and one of them was three hours long. I need to run them till the radio dies to just see how long they will last at some point, but for now I know I can get at least three hours out of them. Also note that it is 10 AA rechargeable batteries, this gives me almost 14 volts which is what a car battery produces when new.

Penntek TR-35 QRP transceiver operating at Eagle's Nest US-0716 POTA activation with go bag setup — The station assembled and under power at Eagle's Nest (US-0716). You'd be surprised how long this radio runs on 10 AA batteries. I've never drained them during an activation!

RG-8X coax cable routing for 40m EFHW antenna showing SWR tuning adjustments field setup POTA — Pointing to how I routed the coax. Started with it in a U-shape and got 2.6:1 SWR. Straightened it out and SWR dropped to 1.7:1, much better! This is why you check things in the field.

Here I am pointing to the coax that I used showing how I laid it out. I started with it in a “U” shape at first but the SWR showed to be 2.6:1 and I did use this for a bit as the TR-35 has final protections that make it pretty much impossible to damage them.

After a few minutes though, I decided to straighten the coax and this moved the SWR down to about 1.7:1 making me much more comfortable. I then checked all the bands that the TR-35 covers and only 30 meters was not usable. So that is why you see contacts on three bands instead of 4 today. Haha

40m EFHW end-fed half-wave antenna support system showing tension cord setup at POTA activation — My makeshift antenna support keeping tension on the wire and keeping it off the coax. It worked okay, but next time I want to get the wire higher. 30-40 feet would be better than the 15-20 feet I got here.

This is what I came up with to keep tension on the wire antenna and keep it off of the coax. It worked OK, but it the future, I would prefer to get the antenna higher. I also want to add another piece of cord so I can raise the transformer end of the antenna off the ground too. I think this will also help with radiation angle and pattern. The Reliance Antenna EFHW works really well and I am glad I got one from them. This is one of those items from the “Ham Made Gear” forum on QRZ.com. I have bought a few items from this area and have never been disappointed.

In the below photo, you can see my truck parked where I normally activate from and on the right side of that are a couple of trees that I tied the antenna up into. It is strange looking out on it now that it is cleared compared to just a few weeks ago.

Eagle's Nest US-0716 POTA operating location showing truck 40m EFHW antenna deployment trees Florida — Wide shot showing my truck where I normally park and the trees on the right where I tied up the antenna. This area was just cleared a few weeks ago so it looks different than it used to.

AA battery holder with melted springs from short circuit damage ham radio power safety POTA lesson — Here's what happens when you short circuit a 10-cell AA battery pack! The springs melted completely through the plastic housing. This is what I get for storing it with the power connector attached. Live and learn!

The Battery Pack Disaster (And What I Learned)

Now I need to tell you about the battery pack disaster, because this is the kind of thing that happens when you're figuring stuff out in amateur radio!

When I pulled the batteries out to charge them before this activation, I noticed the springs were melted completely through the housing. Like, melted through the plastic and everything. It took me a few minutes to figure out what happened, and when I did, I felt pretty dumb.

Here's what went wrong: The power connector barrel plug has the ground connection on the outside ring. When I stored the battery pack in the bag with the power cord attached, that barrel connector must have shifted and contacted one of the metal points along the battery bank on the outside of the holder. This shorted several batteries directly to ground!

Turns out when you short circuit AA batteries, they dump a LOT of current very quickly. Those poor springs turned into heating elements and melted the plastic housing. I'm honestly lucky the whole thing didn't catch fire or rupture the batteries. This could have been way worse!

What I learned (the hard way):

NEVER store the battery pack with the power connector attached. Ever.
A simple inline fuse would have prevented this entirely. I'm adding one.
I stretched out the melted springs and the pack still works, but I'm watching it closely.
I now store the last battery in the bank in a separate ziplock bag so nothing can short across the holder.

This is why we test equipment before we need it in an emergency! If this had been a real emergency situation and my battery pack was dead because of a storage mistake, that would have been a problem. Now I know better, and hopefully you can learn from my mistake without melting your own battery pack.

‍ ‍AA Battery Power: 3+ Hours of Runtime

Let me talk about why I went with AA batteries instead of the fancy LiFePO4 packs everyone recommends. Yeah, LiFePO4 batteries are great. They're lighter, hold more capacity, and last longer. They also cost $100 to $200 for a decent pack!

This 10-cell AA battery holder cost me $12 on Amazon, and a set of 10 Eneloop rechargeable AAs runs about $25. That's $37 total for a power solution that gives me 3+ hours of runtime with the Penntek TR-35. I've done a three hour activation and never came close to draining the pack.

Even better: AA batteries are available everywhere. If I'm traveling and forget to charge my batteries, I can walk into any gas station or convenience store and buy alkaline AAs to get me through an activation. Try that with a LiFePO4 pack!

The 10 cells in series give me about 14 volts when freshly charged (this presents a small problem with Alkaline batteries as the voltage is greater by .3 volts! I guess I need to get two dummy cells so I can “detune the pack for Alkaline batteries), which is perfect for the TR-35. As they discharge, voltage drops to around 12 volts, but the radio still works fine all the way down. I typically recharge them when I get home, even if they're not fully drained, just to keep them ready to go.

Is it the most elegant power solution? No. Is it the lightest? Definitely not. But it's cheap, reliable, and universally available. For a go bag / emergency radio setup, those qualities matter more than saving a few ounces.

Melted battery holder springs close-up showing short circuit damage amateur radio battery safety — Close-up of the melted springs. The barrel connector contacted the battery holder and shorted several cells to ground. Those springs turned into heating elements real fast. I'm lucky it didn't catch fire!

POTA field logging notebook showing contacts on 20m 17m 40m bands Eagle's Nest US-0716 activation — My paper log showing contacts on three bands (20m, 17m, 40m). 30m wouldn't tune because I haven't trimmed the antenna to resonance yet. I still use paper logging as my primary method in the field.

Complete Go Bag Checklist and Cost Breakdown

1. Get the antenna higher I only got the wire up about 15-20 feet using the tree right next to my operating position. This worked fine, but higher is always better for HF propagation. Next time I'm bringing a longer throw line so I can aim for branches 30-40 feet up. The extra height will help with DX contacts and cleaner signal patterns.

2. Add a second cord for the transformer end Right now the EFHW transformer just hangs near the ground. I want to add another piece of cord so I can raise that end off the ground too. This should help with the radiation pattern and might improve performance on the higher bands.

3. Inline fuse for the battery pack Yeah, after the melting springs incident, this is happening. A simple 5-amp inline fuse between the battery pack and the power connector would have saved me a lot of stress. I'll add this before the next activation.

4. Pre-tune the antenna The Reliance Antennas EFHW comes cut long so you can trim it to perfect resonance in the field. I still haven't done this trimming, which is why 40 meters wouldn't tune properly (SWR was a little high). I need to take an hour and actually tune this antenna across all the bands the TR-35 covers. Then I'll know it'll work on 40m,, 20m, and maybe 17m (if I can live with the SWR) without field adjustments. (30 meters never tunes on these antennas so I dont count it.)

5. Add a small groundsheet The bag sits directly on the dirt/grass right now. A small tarp or groundsheet would keep everything cleaner and drier if I'm setting up in damp conditions. Nothing fancy needed, just something to protect the gear.

What's working perfectly:

The bag itself is the right size
Having backup coax has saved me multiple times
Coax with ferrite common mode choke from ABR Industries
The AA battery runtime is more than adequate
The throw weight works great
Everything fits and is organized

Overall, I'm really happy with how this kit performs. These are all minor tweaks, not major problems. The core concept of "everything in one bag" is solid!

Let me give you the actual numbers from this Eagle's Nest activation using just the go bag kit:

Activation Details:

Park: Eagle's Nest, US-0716
Date: November 13, 2024
Equipment: Penntek TR-35 at 5 watts QRP
Antenna: Reliance 40m EFHW at ~15-20 feet
Power: 10 AA rechargeable batteries
Bands: 20m, 17m, 40m (30m wouldn't tune)

Contact Breakdown: I started on 20 meters calling CQ and had a good little run of contacts. After working through the initial pile-up, I switched to hunting for other POTA activators on the band. Then I moved to 17 meters (one of my favorite bands these days!) for a few more contacts before finishing up on 40 meters.

Total activation time was probably 90 minutes, and the batteries still had plenty of charge left. I didn't drain them even close to empty. This confirms what I've seen before with this setup: you can easily get 3+ hours of field time on a single charge of AAs.

The go bag concept worked exactly as intended. I grabbed the bag from my truck, walked about 50 feet to my operating spot, threw the wire up in a tree, and was on the air in maybe 15 minutes. When I was done, everything packed back into the bag just as quickly. No loose gear rolling around in the truck, no forgetting pieces of equipment. It all stays together!

David Saylors 11/6/24 David Saylors 11/6/24

Rainy day CW POTA is the best...for me.

When I set out to activate a park today, I didn’t know where, but rather, only how I wanted to do it. I have been using FT8 so much lately that I got to missing my little CW only radios.

Today saw the re-emergence of the Penntek TR-35 and all the little widgets I made to go with it. I really love this little radio and now I have built an actual travel kit around it so if I wanted to take it somewhere on a plane, the kit will fit in my carry on baggage.

The travel kit doesn’t include the s-meter module or power pack/speaker, but those are “luxuries” anyway. The kit does have everything needed to get the radio on the air and making contacts and that is all that it has. Anyway, let’s get to today!

Pictured above is the radio and the “S meter” I built to go along with it. This meter works really well and makes using the radio just a little more fun for me. Is it needed? No, not at all, but that isn’t the point. This needle bouncing around while I copy code somehow is soothing for some reason and I can see how strong the signal is visually as well. I wrote about how I built in in this blog post.

Another thing of note is that this tiny little N6ARA key works REALLY well. Way better than something this simple should work… It actually works so well that it is worth using as a regular key. It is that good. Now to be fair, I dont know what the life of the key would be as it is PC board material so the contact thickness isn’t that much, but these keys do work really well. It takes a while to get it dialed in (read that as adjusted to your sending feel and style) but once you do, it is amazing how well it works. I should have gotten the larger variant, but I had this silly idea about minimalism and because of this, I got the little one.

Getting the key adjusted correctly and then some practice using it and this thing is amazing. Take it from me, if your not super concerned with every gram of weight, then get the bigger unit. It gives you so much more to hold onto that it isn’t even a option for me now. I still have the small one, but I do plan at some point to get the larger case for it.

I posted this screen shot, of my spot on the POTA website, because I wanted to thank David- WA2OTC for going to the trouble of spotting me on the website while I was at the park without good cellular signal. He even came back to me and let me know that he had gotten the spot on there before moving on with his hunt. Thank you David!

It was really nice to not have to worry about getting on the website and getting myself spotted. You are probably thinking, then how did you get the screen shot? Well, I didn’t have a total black out, but just weak signal, so I simply loaded up the website and waited the 5 minutes or so for it to populate (seriously, I thought it would never load) so I could grab a screen shot for the blog. It would update EVER SO SLOWLY if I left it on the page. This location is a geographical oddity, it is close to the city but in a particular spot where there is terrible cellular coverage for some reason.

Welcome to fall and winter in the south. I have realized over the years that we get most of our water in the winter and I have planned accordingly. Things like the tape on the coax connector below to keep the rain out during an activation… Don’t forget to keep a roll of electrical tape in your car. Another trick I learned in working electrical maintenance over the years is that if you wrap the tape inside out (sticky side to the outside) then it wont leave residue on the cable and it works just as well for this purpose. We used it on factory motor connections so the rubber insulating tape would not stick to the connectors and it make changing the motors so much easier.

This exact weather event is what drove me to build the truck-tenna mount and figure out a power source for inside the truck cab to start with. POTA in the rain can still be fun as long as you plan for it.

Another thing that has happened at this location is that someone has cleaned it up… I am guessing the park service since there were chainsaws used…a lot. The cut all of the dead trees out as well as cleaned up all the dead-fall and then mowed the entire site! This is the first time I have seen this happen since doing POTA! The photo below was take just a month or so back.

So after getting the radio setup and checked for SWR, I hopped on 20 meters right away. I wanted to be sure to get the activation fairly quickly as I didn’t a long time to stay and I also was using my Penntek TR-35 radio which is QRP power too. This gives me the best possible chances at activating…well, I underestimated the capability of the radio a little as you can see from the log. LOL. I first hunted AC4BT to just see if I could get through, this is because lot’s of activators today use 100 watt radios so just listening to the other stations no longer gives you an idea of how strong your signal will be. I make my point with the signal reaport I got back. He was booming into my radio and I was a 339 to him. 339 is workable so I moved to a clear spot, called QRL a few times, then called CQ and that is when things took off!

For almost the next hour, the bands were on fire! The only time there was a significant time between contacts was when I tried to reply to KM3STU and couldn’t get him. He came in strong and then vanished. Shoot, at one point I worked Germany! He was closer to the noise than the other stations but I was able to dig his call out after a minute. It is ALWAYS awesome to work another continent with a QRP radio!!! Alas, after about 45 minutes of non-stop contacts, the band just fell silent for me and after calling CQ for a few minutes, I called QRT and shut down the station as I needed to pack up anyway. This was a great POTA activation for me and one where I look back fondly at how much fun a tiny little radio can be.

I will say it again, if you have thought about activating a park, just do it. If you have hunted, then you know the exchange. Just write the park number at the top of the page for when you work another activator and the want to exchange park numbers with you. You can see that I paper log in the field then enter it into a computer when I get home to submit it to the POTA site so the hunters get credit. I will be honest here, if the hunters didn’t get credit for the contacts as well, I wouldn’t bother uploading the logs at all. For me it is about the experience and not the awards, this is why I have never submitted anything for awards from any organization. I just like operating on the air. So those logs upload are for you, not me… you see, without the hunter, this would not be a huge hobby like it is today, so I want them to get the credit they deserve. Anyway I will stop rambling and until next time, get your radio out and talk to someone on it!

David Saylors 10/30/24 David Saylors 10/30/24

Getting back to my roots…with CW

Today I activated park US-2169 with the Ten Tec Scout and only used CW.

This was a pleasant change from the FT8 I have been using so much recently. I was actually planning on switching to SSB then FT8 as well and use all three modes in one sitting…but…CW was working SOOOOOO well.

I also decided to setup at the picnic table by the canyon rim so I could use a 41’ wire antenna and a tuner. This allowed me to go up to 10 meters as I checked the spot page and a bunch of people was already there. I worked on getting the antenna tuned a while, only to find that I had used it wrong. Once I figured this out, I was able to get it to tune to about 1.5:1 and this is perfectly fine for a Ten Tec.

I was blown away by what happened next.

Here is what I took with me today… all those cases have different radios in them. The orange case is the sBitx (my goto FT8 rig in the field) the green case is the Ten Tec Argonaut 5 and the tan case is the Ten Tec Scout. I was loaded for bear. Lol. I was going to use the Scout for CW and SSB and then switch to the sBitx for FT8. Then why did I bring the Argonaut 5 out? Because the keyer and paddle are in that case that I wanted to use. HaHa. I also used the tuner and some cabling out of that kit as well.

Let’s talk about the Scout for a minute. This is a unique radio in that to change bands you change these modules that plug into the front of the radio. I have the whole set of band modules for my Scout and keep them in the hard case with the radio. It is an interesting little radio that also has a unique tuning device. The radio has a PTO instead of a VFO. So the knob has a distinctive resistance when you turn it as it is a mechanical screw driving a core into an inductor. This also means it remembers the frequency you are on without the need for a memory battery.

I kept the nanoVNA on the table for tuning when switching bands and I elevated the tuner on a pair of lineman pliers to make tuning a little easier. My Scout is unmodified from original and works really well. It does have some quirks but nothing that is a deal breaker.

The station as operated today. I like this spot as it is also in the public view and can sometimes spark conversations with passerbys. I had a conversation with a man and his wife on this day and he was in the signal corps in Korea and was copying the code as they walked by. He waxed nostalgic for a few minutes and we had a wonderful conversation and then they were gone…

The below photo shows the tree where I strung my antenna up to and you can see the table in the background it went down to. I like to string up a huge 65’ wire most of the time but today I just used my 41’ random wire since it was already in the kit.

These new LiFePO3 batteries are truly amazing to me. They weigh almost nothing and I operated for two straight hours at 50 watts and the battery was still at 13.26VDC. This blows my mind. I can pick this battery up with two fingers! I also ran it through my fuse distribution block so everything was fused.

This log shows how awesome the band was on this day. I started on 10 meters CW as I was listening around and the first call I copied was England! That was when I knew it was going to be good. I didn’t get him, but shortly after I started calling CQ and 6 out of the next 10 contacts were DX!!! The first one was Chile and I am pretty sure that is the first Chilean I have ever worked.

After that I noticed the rest were from the European area of the world which is still awesome! The other domestic callsigns were still very far away and I was stoked to mess with other bands as well to see what I could hear. After these initial 10 QSOs, I found that the band was fading so I figured I had hopped on the air at just the right time and caught a wave. At this realisation, I figured I would give 17 meters a try and see what happens. It was much more difficult for some reason, not much activity at all… I guess everyone was up on 10 meters… haha.

So after that, I figured I would just test 15 meters before calling it quits for the day. Well, I must have hit a band opening on 15 meters as well. The calls started coming in and as you can see below I got South Africa! That is also a first for me!!! I normally cant hear Africa since I use less than ideal antennas. I had a blast on 15 meters and the logbook reflects that. I even worked two “regulars” that I know by name but have never met in person! KJ7DT - Paul in Idaho and K9IS (who I have written about before) - Steven in Wisconsin. Both of these men have worked me well over 50 times and I am pretty sure Paul is over 100!

It is really cool to get “Z” calls in the log though as I rarely hear this call letter on the air. I always think it is way off, and sometimes it is, like the South African station but then I get one and it next door in the Caymen Islands too…lol.

This was an awesome day and I am glad you followed along in the story with me. Until next time, I hope to work you on the air!

WK4DS - David

David Saylors 10/19/24 David Saylors 10/19/24

Jumping on 40 meters right quick…

Today saw me testing a theory, that 40 meters wasn’t closed just because it was late in the morning…

When I got to US-2169 today, I wanted to get on the air quickly, so I decided that I would activate the Sitton Gulch parking lot instead of going to the top of the mountain. This one thing adds about 40 minutes to my operating time as it takes me about 20 more minutes to drive to the top of the mountain from here and then there is the drive back down. Armed with this extra time, I decided to also add a long radial so 40 meters would tune up to a usable SWR. I was able to get the SWR on 40 meters CW down to about 1.6:1 and this is what I made all my 40 meter contacts at. The beauty of Ten Tec radios is their notoriously robust transmitters and the legend that they can survive transmitting into 10:1 SWR without ill effects. I have personally used my Argonaut 5 in 2.5:1 conditions and had no problems at all.

Today I thought I would just jump on 40 meters for a minute and see what I could scare up on CW then move over to FT8 before heading up to 20 meters. I was not ready for the pile up that happened next… It was interesting as there really wasn’t much activity on 40 meters at the time when I hopped on. It was almost lunch time at this point (late morning) and the noise on the band was picking up. I sent out my CQ a few times and it didn’t take long to get an answer. I also spotted myself on the app too and I am certain this helped immensely as well.

I worked over 10 contacts in about as many minutes and was stoked to have bagged the activation so easily. I switched over to FT8 now that I have cleared my little pileup on CW and see what I can find there!

I simply added a couple more radials to the antenna to help with SWR so that I could operate on 40 meters today. One of these radials was over 30 feet long! The 40 meter ham stick that I have is not that great of an antenna from what I have seen. The SWR is really touchy with it and I can not get it to tune without several large radials helping it. I dont know what I am doing wrong with it, but I really need to figure it out as the 40 meter band is a lot of fun!

The measurment kit below has becoume part of my permenant truck POTA kit that I take with me everywhere. It has the nanoVNA and all the associated widgets for it as well as a simple little multi-meter to check things with out in the field. This has been very valuable at times and a I recommend everyone carry a simple meter with them.

Here is a simple little hack that I found with my Ten Tec Argonaut 5 radio that I though was cool. You can make up a front (mic plug) connector for the keyer cable instead of using the tiny one on the back if you will simply wire the keyer contact from the keyer or key across the PTT contact on the mic plug. It works flawlessly and is simpler to setup for me. I have the cable for the back too should this one fail for some reason, but this is more elegant for me. Notice all the RF blocking devices I have added to the lines to reduce (read that as eliminate) erroneous characters from being sent due to stray RF.

After my little interlude on 40 meter CW, I switched radios to the sBitx to be able to work some FT8 on 40 meters as well… This was not a great idea as the SWR was 3.5:1 in the part of the band and I didn’t want to risk damage to the finals so I made one contact and then moved to 20 meters for the duration of the activation. Once on 20 meters, this is where things REALLY took off for me today. I started hunting and pouncing on contacts on FT8 before I finally just setup on an empty slot and started calling CQ myself. This produced a lot of contacts. A really good run ensued and I was glad to see that I was able to put many calls in the log on this day with the sBitx. Shoot, I even worked a couple of SSB contacts as well, but it was a struggle to be honest with only about 9 watts or so in the SSB portion since my antenna is tuned for the CW portion of the band.

Here is a rare glimpse into my “go” kit for my Ten Tec Argonaut 5 as a CW kit. I need to add the microphone to it so I can use it for SSB as well but I am not sure if the SSB mod has been done to this one yet. Haha. It works so well for CW that I have not bothered to check! But the kit contains the radio, tuner, wire antenna, key and keyer plus all the cabling to get everything connected. It is only missing a power source but that is by design. I carry batteries for remote ops or plug into the truck for mobile operations which is why I dont have a battery in the kit.

Here we have yours truly operating the sBitx on FT8 and to be honest, it works almost too well for this. To the point that I am almost not even interested in the other modes with it… Almost… I love working from the bed cover if it is nice outside as it is the perfect height for my uses.

This was a great day for radio and the logbook reflects it, looks like the solar cycle is picking up for the winter run! This is the time to get on ten meters and work some DX yall! I should know as the next blog post will reveal next week!

David

David Saylors 10/16/24 David Saylors 10/16/24

Activating a park in bad conditions

POTA activating in bad conditions can be challenging… for some modes. Seems that FT8 doesn’t really care if the bands are crappy and will gleefully allow you to play radio anyway.

This was an experiment to see if the sBitx amateur radio could work in terrible space weather like you see below in the report.

The above and below photo show how fast the band conditions changed on me while activating on this day. The band noise could be seen on the display “walking” across the band segment at times. This band noise would pretty much wipe out what you could hear on the band, but the radio could still decode the FT8 signals so I was able to work almost 20 stations in about an hour even with this sort of noise coming into and out of the band.

I normally dont bother activating in bad band conditions, but this day I really wanted to see just how good FT8 was at extracting signals from the noise. I can honestly say that I was impressed by the performance of this mode. Digital modes have their place and this is very much one of those places. Weak signal in poor band conditions shows just how important it is to use all the modes available to the amateur radio operator. I was once a die hard CW only op and to be honest, it is still one of my favorite modes, but of late I have started getting into SSB more and now I am also dipping my toe into digital modes more and more and I am really liking it. Dont limit yourself out of a stigma like I did, you might just like what you find.

Below is a photo of the display that shows something that i had never seen before and that is the pulsing band noise. That was a new one for me. It too would come in waves and these would last much longer it seemed. The sBitx just kept chugging along though, I would sometimes pick calls and sometimes answer calls and this is what makes FT8 awesome. I couldn’t have possibly made SSB contacts in these conditions…

Here you can see the operating position for the day. Perfect blue skies and nice temps makes for a great day on the air at a park. I had to goto this spot as the lower lot was completely full since the weather was so nice, it was fall and a Saturday. Sometimes going to this spot has it’s perks like lower band noise from the campground inverters and such so I dont really mind it.

I had planned on using a battery and setting up on the picnic table I usually occupy down next to the canyon rim, but there just wasn’t anywhere to park and I didn’t want to wait on someone to leave just so I could park.

This radial is on it’s last leg. I have twisted this broken radial back together for months now and on top of that, the connector on the other end has also broken off. This is almost comical as this is the best performing radial in my set! That is why I am reluctant to repair it at this point…lol. It just works and if it ain’t broke (figuratively) then dont fix it.

I dont know when this bug (I think it is a jumping spider) decided to join in on the fun but here he was playing on the antenna mount. By the time I finished the activation, this little guy was long gone. Kinda fun to notice the little things like this when you are out in the park.

By the end of the activation, I had worked 18 unique contacts and garnered one dupe because I didn’t read my logbook very carefully and called one ham two times…then I decided to attempt to work some CW. This was pretty futile though as I only worked one contact out of about 15 minutes of calling as this is abysmal for me when I work CW. I can usually work about one call per minute even when I am running QRP power levels. So when I only work one…that is bad band conditions. The stations would literally just disappear then reappear and it was impossible to get complete calls so I called it quits after one.

All in all, it was still a great day in the field. Hope to work you soon!

WK4DS

David Saylors 9/25/24 David Saylors 9/25/24

sBitx V3 HF radio special functions

I recently activated a couple of parks and decided to add a bluetooth keyboard to the sBitx V3 and see how operational it would be like that.

On this day I decide to activate Chickamauga Battlefield but first it seems a “widow maker” dead tree fell into the pull off at US-0716… I cleared what I could without a chainsaw and then setup the radio.

The below view gives you a good measure of just how big this “parking lot” is…lol. This lot would hold two small cars or my truck and a motorcycle and that is about it. The cars going by are the worst part though. These cars sometimes emit terrible amounts of RF hash… first world problems I guess…

I setup the usual antenna system but only for 15 meters as I was feeling a bit adventurous today and figured I would stick it out on 15 meters till I got the activation secured. I could have done the same thing in 15 minutes on 20 meters using CW, but there are plenty of ops on 20 meters already so I figured I would warm up another band instead. Well, the QSB was obvious when watching the FT8 waterfall, you could see the band come in and out as the stations would get real loud then fade almost all the way out. This made FT8 challenging since it takes a couple of minutes to complete the series of messages. None the less, I was able to get 11 contacts anyway, even with the frustration of some more that never did complete… but so is HF, she is a fickle girl at times…

Today saw the common mode choke come back as I had it nearby and the SWR was a little off. So I threw it inline with the radio to keep it happy. These are really simple to make and I show how I do it on a video, that is in live-stream format, on YouTube, at this link if your interested. Link to video about making a common mode choke for QRP work (it can probably handle 100 watts without issue but I have not tried it) and POTA ops.

Below we have the operating position for today, notice I didnt even bother with the CW key today as I had planned from the outset to only work FT8 and then pack up. Took me longer than I had anticipated but I did it! haha. Well, to be fair, I did have a CW key in this photo, you see the sBitx will also send CW from the keyboard. I use this to great effect at the other activation I am going to talk about shortly…

The one thing I really like about using 15 meters from a park with a ham-stick antenna is that I am able to work DX pretty consistently. As we see here I worked 5 DX stations out of the 11 I got into the logbook that day. That is a phenomenal amount of DX stations for me. I just seem to get REALLY good propagation when I get on 15 meters for some reason. I will get one every now and then on 20 meters, but I get them regularly on 15… just something to think about if you are into chasing DX and want to also do POTA…and use a ham-stick antenna. You see every contact you make from the park counts towards your POTA log, so even if they are not participating in the program, like a recent ragchew I had while at a park, still counts to your 10 you need for that day.

The other park I went to recently was Booker T Washington just NE of Chattanooga TN. I have not been back to the park for a while so it was nice to put it in the log again. Instead of struggling around on 15 meters at this location I chose to run 40 meters and 20 meters for a while instead. I hopped on 40 meters FT8 to start with as I have not been on that band from a park using FT8 yet. It did not disappoint. There were a few stations still lingering on the air so I was able to work several of these stations before the band noise got so bad that I could not complete contacts and further. I even worked the W0E special event station which is really cool.

This is a really old park and has changed over the years. These were once campsite areas but have since been simply turned into day use “picnic” areas with most of them essentially becoming simply parking spaces for people that go for walks. There are a few that have picnic tables and even grills but most are now just parking spaces along the loop.

After working 40 meters FT8 for about 1/2 hour or so, I decided to give keyboard CW a try on the sBitx V3. This also did not disappoint. I was surprised how easy it was to transition from using a paddle to using the keyboard to send CW. It did take a little getting used to for me to become proficient with it, but after just a few minutes it was like I had been doing it for years and I even figured out the keyboard short cuts for the memories too, so I could use them easily for the exchange and such. This made it easy to log as well as send so I kinda liked using it this way to be honest. It is more fun to me to use a keying device of some sort, but if I forget my key, I now know I can still get on CW and make POTA contacts with it easily. That is a nice option to have in a 400$ radio to be honest about it. Well, to be fair, if you have used an sBitx for sending CW, then you also know how frustrating the keying is with it. It is possible to use it to about 20 WPM or so without much issue but above that, the keying delay because of the way the code is written, will cause the radio to send mistakes. Once you learn to hold the key just a little longer than usual it works just fine at speed of 20 WPM and less so it isnt a huge deal for me. Much over that though and the radio just wont work as of right now. From what I have heard, there is a beta of the next version of the code that will address this problem, but I am not able to compile the code properly so I am patiently waiting for the official release to drop before upgrading again. JJ just released an update to his fork of the code as well and it has a bunch of new features like a tune button and such, but I am also waiting on that one as well so that the bugs get ironed out before I install it on my machine. Now back to the activation…

After that I hopped on 20 meters FT8 and jumped into the fray for a few minutes to see if I could grab a few more calls for the day right quick and that would be a yes! I got 3 more stations in the log using this mode on 20 meters as well. What a day!

Today also saw nice enough weather to setup on the bed cover and these two photos show how I have to do this if I am on the truck power cable from the cab. It is just long enough to reach out the window and power the radio…lol. Barely… (I really should make a longer power cable or something…haha) This worked out today as the whole location was in the shade so I didn’t have to fight off the sun while trying to activate. A lot of the time, this is the reason I don’t operate from the bed cover in the summer, it is in the sun and just plain hot…

As you can see below, the height is about right for me activating too, I can write as well as operate the radio and it is at just the right height for me and my stature. If you like to work POTA, and you do regularly activate, what is your normal operating position? I have a few with this one being one of my favorites even though I don’t use it much.

Thank you for following along and I hope to work you on the air soon!

73 - WK4DS

David Saylors 9/18/24 David Saylors 9/18/24

POTA AAR using 3 modes on the sBitx transceiver

Today marks the second deployment of the sBitx and me using it on three different modes.

You see, I spent a good bit of time recently solving the weak audio problem with the SSB mode in this radio. I found the microphone input level is really weak and there was a common solve by installing a more powerful microphone element in the hand mc. I tried this approach and it really didn’t help much for me. l was essentially still yelling at the radio to get it to work. Pictured below is what my radio looked like on the work bench as I worked on the audio level for the microphone input.

I ended up building a pre-amp circuit to boost the audio several dB and this fixed my weak audio problem. I wrote about it in the blog and recently published that post as well if you would like to know more.

Back to the activation, it was a beautiful day and wasn’t really all that hot either. This is a nice departure from the July temperatures I had been dealing with recently.

I setup in my usual place but indexed the truck about 90 degrees so the sun wouldn’t shine directly in my open door. This allowed me to leave it open for the most part. I get so much more aurflow with the door open as opposed to just rolling down the window.

I also ran my 20 meter ham stick on the truck hitch mount I made and just deployed the two radials I tuned for 20 meters. I planned on this activation being kinda short so I didn’t setup for any other band since 20 meters is so active I should easily get my activation locked in on just that band.

I do have some future plans for the antenna mount though. One of thise is to incorporate multiple ham stick mounts (2 specifically) to allow for band hopping without having to get out of the truck. This way if I am setup on a rainy day, I can go ahead and setup two bands at the beginning and then just stay in the truck.

I am beginning to think I want to install a screwdriver antenna again like a Tarheel or something like that and just use that for the quicky ones. I have heard good things about Tarheel antennas and it would make a bunch of my activations so much faster.

I use these CB antenna mounts you get from the truck stops for my base connections. It is an easy way to build an antenna mount from scratch as it has everything you need to attach the antenna to the base.

Something else I like about the sBitx is that even though it is a touch screen design, it can also be mouse operated. This makes using the radio about 100 times easier as some of the touch functions can be fickle. Like picking a station to call on FT8 from the list. It isn’t super hard to do by hand but it is MUCH easier to do with a mouse. Because of this, I have started bringing a USB mouse with me on my activations.

Yet another reason I like this radio… lol. It can also use a USB keyboard as well and you can “type” CW with it if you want but I dont worry with that as I really dont have the room for the keyboard at this time. Maybe at some future point I will add a shelf for those items. Haha.

All in all it was a great activation and I really enjoyed the time at the park as well. It was really cool to be able to use SSB with this radio! That alone made this particular trip unique. I think prior to this that I had made just one SSB contacts total! ONE! Now that mode is going to be showing up in the logs more and more and I can’t wait to share those trips with you one here.

WK4DS

David Saylors 9/11/24 David Saylors 9/11/24

Working on the microphone input of my sBitx

This is what a project in progress looks like for me…

I have been hobbled by the low audio in my sBitx since it was purchased back in 2023. This radio is a godsend for FT8 but the SSB microphone level was almost unusable. It was weak and you had to yell at the radio to get it to work at all. I didn’t really want to go into the software and start changing stuff in it, so I decided to bring the level up by adding a pre-amp to the circuit.

So I get out a breadboard and build up a simple audio amplifier circuit on it with a 2N3904 transistor and set about to see what levels I could get with a simple 9VDC battery powering it and feeding the input with the actual microphone I plan to use. I used a couple of potentiometers to adjust the input level and the gain of the circuit so that I could tune it to work with my radio. Below is the circuit I found online (why go to the trouble of designing one from scratch when it has already be invented?) So I built it up and changed 10k resistor and the 100k resistor with the pots I mentioned earlier and it was time to put the scope probe on it and see what I got.

It worked beautifully well. I could drive it to clipping if I wanted but I had PLENTY of gain before that happened. Way more than I needed I would find out later when testing it on the air with my friend on 80 meters. I chose to setup the bench test by simply getting the board out of the radio and powering it without the Raspberry Pi installed, this would power up the audio amplifier circuit without the hassle of it biasing the RF section. I put a scope probe on C119 at the output of the transistor (which you will notice looks very similar to the one I built actually). This circuit powers up when the switch is turned on so you dont need to even have the Pi installed to work with this circuit. For testing I simply connected the output of my amp to the mic jack with jumper wires and then spoke into the microphone while watching the scope. It worked really well to be honest. It worked so well that I looked at the sBitx circuit and figured that full output was 3VDC peak to peak or so as there is a 3.3V zener diode on the input of the IC this circuit is feeding. 3.3V logic protection if what I am figuring and these zeners are clamping the signal to that voltage max for safety.

This was a mistake turns out as it needed me to dial back the input significantly to get good quality audio out of the radio, but I had signal finally! It worked!!!

The yellow trace is what was going into the mic input and the purple trace is what was coming out of the pre amp I built. I was well pleased with this. I then proceeded to move the parts to a perf board and install it into the radio semi permanently to test it.

In the photo below I am pointing at the little “daughter” board I built with my pre-amp circuit on it. I tapped power from the input right at the massive reverse polarity protection diode that I also installed in my radio. The factory diode is really small and if you didn’t consider a small enough fuse in your power cord or worse…no fuse at all, then it will burn open after a short time and will let the reverse voltage wreak havoc on your radio. The reason I know this is that it has happened to others with this radio. This diode, combined with my 10 amp fuse, works like it should. It will blow the fuse every time and not damage the diode. I tested the idea a few times with a few fuses to make sure it would work and it did.

Here you can see how I hard wired the amp into the radio. I lifted the end of the RF choke that was connected to the microphone port and soldered my pre-amp output to the inductor and then my pre-amp input is simply soldered into the through hole the inductor was in. This made for a simple and non-permanent installation should I want to remove my mod at some point. After this, I simply wrapped the board with a little electrical tape and zip tied it in place so it doesn’t wiggle around too much while I test it in the field some. Once I got the pre-amp tied in I realized I was “double biasing” the electrolytic DC blocking capacitor that I was using to couple the pre-amp to the amp in the radio. So I simply removed the SMD resistor RD21 as this resistor is normally used to power the microphone elements and I had my own bias resistor already in the circuit.

Here is what the audio waveform looked like on the radio when transmitting later after I got the radio put back together. Before ( I should have taken a photo…) it was barely visible when you would talk into the microphone. and it was showing power out too!!! Success was had the next day when I made two SSB contacts with it on a POTA activation.

I hope this inspires you to make some improvements to your electronics in some way, this was really fun and rewarding in the end as it enabled a mode on this radio that had been previously disabled by default.

David Saylors 8/28/24 David Saylors 8/28/24

POTA at US-0716 with only Digital Modes...

My plan was to only use FT8 and get the activation as quickly as possible, but in the end it ended up a little differently. This POTA park is a national military park commemorating the battle of Chickamauga during the US Civil War in the late 19th century. It is now a recreational hot spot along with a tourist destination so they have all the trappings of a outdoor recreational area along with the monuments about the war. This trail head was across the street from where I parked the truck today.

Another reason for the singular mode was that it would only require the use on a single radio this time since I am currently using the Ten Tec Scout along with the sBitx SDR for my POTA activities. I only deployed the sBitx SDR today so I could stay inside the truck and run the air conditioner as well since I didnt need to hear as well as I would if I were doing CW or SSB.

By only using one radio the rain that moved through the area didn’t hamper my activity at all. I was able to get setup quickly enough that I beat the rain and was on the air before it started to fall.

I like this location on sunny days since it is in the shade, but today it was overcast and rainy and this didn’t really matter. I did like it because it is “RF Quiet” and there is little to no RF noise except when certain cars drive by that are a little noisy.

I used my field expedient sealing technique again today, I know this is not a real seal but it will shed water long enough for me to complete my activation and then I can break it down and stow it in the truck easily enough. Long term would be a different story, but it works well for me like this for simple short time frames like a POTA activation.

This time since I was going to stay on 20 meters, I simply deployed the two radials that are associated with that band and I ran them at right angles just to see how it would perform, it looked great on the nanoVNA with the SWR running about 1.2:1 across the digital portion of the band.

I meant to get a photo of the waterfall and somehow ended up with an image of the transmit signal and associated info…figures. The point was going to be that the 20 meter section of FT8 was filled with ops today. So much so that is was hard to find a spot to send from. The band segment was that tightly packed today. I had to frequently move as I would go for several cycles with out so much as a hint of someone answering me only to find out that a strong station had setup on top of me and was sending over my little 20 watts. Get a contact, listen to the band a minute and find a new clear spot and repeat. This was the modus operandi for the day. I considered at one point of moving up to 15 meters just so I could more easily find band space, but talked myself out of it since I didn’t want to get out in the rain and change antennas and then worry with the tune of the radials and such.

After getting my minimum of ten contacts on FT8 thereby securing the activation, I wanted one more just so I could have a little buffer if one was a pirate of some such. Turned out that this was a huge problem as it took me a long time to get that last QSO in the log, I even went over to CW thinking it would be easier (which it was not) and finally got that last station… The QSB (signal fading in an out) was so bad that I could almost not hear strong stations that were normally easy to copy, but I did get the one I wanted before going QRT for the day. I grabbed the photo below to show the band fade and it is kinda visible in the signal on the lower edge of the waterfall, but it would go from what I would call S9 to nothing in literally 5 seconds, they signal would just vanish. I was blown away with how bad it was and then I checked the space weather and saw why, there is a ton of solar activity causing terrible band conditions right now…figures.

11 contacts in almost an hour is not a great hit rate for me where I am used to working about 1 CW contact a minute and a FT8 every two to 3 minutes, but it was fun none the less. Any day I can get out and do POTA is a good day. Until next week…

WK4DS

David Saylors 8/21/24 David Saylors 8/21/24

A shorted diode…and the sBitx

I blew a diode while pushing the boundaries of my IRF520 output transistors messing around with FT8…

Troubleshooting was actually pretty simple this time as I chose to use technology to my advantage and simply scanned the parts during transmit with the infrared heat gun and found a diode was 25 degrees hotter than everything else around it. This has to be cheating…

Let’s rewind time just a little so you can understand what I have been doing here… You see, this radio came with some fairly fragile finals from the factory. So fragile in fact, that they sent a spare set with the radio. The IRFZ24N transistors were wonderful, but under full load on FT8 and into less than perfect SWR would prove fatal for them. I ended up killing 3 of them before changing my radio over to the V3 spec. The V3 specification changes the finals and also changes a few other components in the amplifier chain to use them properly. HF Signals sent out a bulletin showing what all needed to be done and it was actually pretty straight forward. I decided to use some IRF520 transistors instead of the IRF510 transistors speced for the update as they had better current specs than the IRF510. They are rated for the same power dissipation essentially, but can handle almost twice the current without damage. This combined with the fact that I had them on hand, led to the construction of a bomb proof set of finals in my sBitx radio!

Once I had them installed, I set the bias and was off to the races. They literally handle anything I throw at them and I have run them hard to make sure they would not fail in the field at an activation. This is good and bad you see, these transistors work so well that I now can get over 65 watts (with the drive set to 100%) on 80 meters with them…and this is a problem.

The sBitx is not engineered for transmitter output powers this high, the original design was for 40 watts maximum forward power. and the components in the amplifier chain are sized accordingly. I learned this when I powered up the machine after messing around on 80 meters and accidentally transmitted into a 10:1 SWR with it last night (probably infinite SWR since it was into the coax with no antenna on it... It blew the 10 amp fuse almost immediately, which I figured would protect the radio…and it did, sort of... I was able to put a new fuse in it and get right back on 80 meters without any trouble at all. I didn’t leave that band though so I had no idea what had actually happened.

Fast forward back to today, I turn on the rig and dial up 15 meters to see what was happening on FT8 there, tune up the antenna with the Comet Antenna Analyzer and the manual antenna tuner and I am off to the races! Or so I thought. Seems when it would go into transmit, there was zero watts going out to the antenna, but the Astron RS-35M power supply was showing proper current draw for 15 meters FT8 transmit! How is it pulling the right amount of amps (6 amps is 20 watts on 15 meters) and not putting anything into the coax? That math ain’t mathing… I remember that whole current law about current going in has to match current coming out, so I start looking around.

I tested 10 meters and it was the same, so was 20 meters, but when I got to 40 meters, suddenly I had power to the antenna again. I also had it on 80 meters as well, full output power was there till I left the two lower bands. Something is either wrong with the 80/40 section OR all of the others. So I take it down to the shop where my test bench is located and rig it to a dummy load to see what I could find with the heat gun.

The photo below shows the diode that is shorted where I pulled one leg, so I could test my theory prior to dismantling the radio to replace it properly. This is a 1N4007 and it is being used to switch the radio’s transmitter band pass filters into and out of circuit. It has four filters to cover 8 ham bands (80 & 40, 30 & 20, 17 & 15, then 12 & 10 is the last one). The diode that failed was on the 40 & 80 meter filter. This essentially turned it on all the time. and also turning off the others by putting the switching voltage on both sides of the other filters output diodes. This makes them all have zero volts dropped across them essentially turning them all off. So only the 40 & 80 meter filter could be turned on at this point. You can see what I am talking about by looking at the schematic below where I am pointing out the diode that failed on the print.

The foreground, in the below photo, is the board showing the new diode in place after removing all the stuff in the background to get to it. You have to literally take the whole thing apart to get to this part of the radio. Fortunately for me, I have done it so much I have memorized the process and can do it in maybe ten minutes. You can also see the two IRF520 finals next to my thumb, you can also see all the heatsinks I installed to help mitigate the heat buildup in the radio.

Did a static test on the bench, just to make sure, and it worked perfectly with the dummy load attached. Luckily I did it right and dont have to take that whole thing back apart! HaHa. In the background is another little project I may write about. Seems the sBitx has this systemic problem with low audio on SSB and I tried the new microphone element others in the email reflector suggested to no avail. So the next solve is a more “active” solution with the use of a small single transistor amplifier is a sort of (pre-amp) configuration so that I can increase the audio signal going into the radio and make it actually work like it should. The radio already has one of these circuits in it, I don’t think it can handle any more gain with out distorting so I want to pre-amp into it with a variable gain setup so I can go into it with 2x, 3x or even 5x the input signal so I can get decent audio out of my radio. More on this later…

Man, I had no idea how messy my bench was till I looked at this photo… I will have to clean that up! Sorry about that everyone…

So today had the real test. I took it to US-2169 and setup in my usual spot and decided that today I would stay on 40 meters till I secured the activation then I would move to 15 meters to see what I could find. Seem I found a lot. 40 meters and hamsticks will usually produce contacts that are closer to home for me, maybe as far away as Texas or Michigan is a long haul on 40 meters but 15 meters is a different story all together. With me getting contacts in Russia and Japan on this trip! If you will notice the power levels are lower, this is because the truck, when shut down, has battery voltages around 12.5 VDC and not 13.8 as these are older batteries, well this produces less output wattage since the voltage is lower. Still had plenty to make a ton of contacts with while I was at the park! Of note here, only the FT8 contacts are with the sBitx, all the CW contacts are with the Ten Tec Scout 555 portable radio. I did scan through the 15 meter side band section of the band and heard zero QSOs so that is why I went to CW. There was a station with a mild pileup on CW and so I moved up 5kc or so from them and set up shop there for a while. I was able to get all three west west coast states a Russian, a Canadian, and Massachusetts! Enough about the Ten Tec Scout though, this is about the sBitx…

The sBitx is up and running again and it is all good now. The radio runs flawlessly (other than the SSB audio) and I am happy as a lark now. More to come as they software gets dialed in for better CW operation!

Hillsborough River State Park: Location and Access

The Antenna Setup: 65-Foot EFHW in the Trees

Radio Gear: Penntek TR-35 and sBitx v3 Performance

Operating Challenges - Sun and Glare

sBitx v3 CW Keying: Improvements and Remaining Issues

20-Meter Band Issues: IRF520 vs IRF510 Amplifier Problems and Receiver Front End Overload"

Multi-Operator Challenges: RF Interference and Antenna Placement

Who Should Activate This Park?

Hillsborough River State Park is an excellent choice for both first-time and experienced POTA activators. Here's why:

Frequently Asked Questions About POTA Activations

What is Parks on the Air (POTA)?

How do you activate Hillsborough River State Park for POTA?

What is an EFHW antenna and why use it for POTA?

Can you run two stations at the same POTA activation?

What's the best QRP radio for POTA activations?

How many contacts should you expect from a POTA activation?

You can help support this channel by using these Amazon Affiliate Links as well:

The Antenna and Radio Setup

The POTA Activation Begins…

15 Meters Gets Sporty!

DX Countries Worked:

AAR POTA Wrap Up

Related Posts

You can help support this website by using these Amazon Affiliate Links:

Planning the Activation

The Setup: Remote Antenna Tuner Configuration

Equipment: QRP vs. Comfort

Operating Highlights

You can help support this website by using these Amazon Affiliate Links:

You can help support this website by using these Amazon Affiliate Links:

You can help support this website by using these Amazon Affiliate Links:

You can help support this website by using these Amazon Affiliate Links:

You can help support this website by using these Amazon Affiliate Links:

You can help support this website by using these Amazon Affiliate Links:

You can help support this website by using these Amazon Affiliate Links:

You can help support this website by using these Amazon Affiliate Links:

Why Build a POTA Go Bag?

Complete Gear Walkthrough: Everything in the Bag

The Penntek TR-35: Heart of the Go Bag

The Battery Pack Disaster (And What I Learned)

‍ ‍AA Battery Power: 3+ Hours of Runtime

Complete Go Bag Checklist and Cost Breakdown

Search Posts