Weather-Resistant UnUn

When camping or on vacation, one of my go-to antennas is a simple 29.5-foot wire and 9:1 unun. In these situations, the antenna is usually up for days, and I have to use plastic shopping bags to protect the unun from the elements. For this project, I attempted to build an unun that can withstand the elements.

I had been thinking about this for a while. I wanted something that would protect the internal parts and provide some protection for the coax connection. Eventually, my stash of PVC pipe odds and ends caught my attention. I figured if this stuff could keep water in, it should be able to keep water out. What I came up with is somewhat weird-looking, but it should do the job

This is the completed 9:1 UnUn.
This is the completed 9:1 UnUn.


Here are the major parts I used:

  • About 2.5 inches of 1.5-inch PVC pipe
  • (1) 1.5-inch PVC end cap (slightly rounded top)
  • (2) 1.5-inch PVC end caps with flat tops
  • (1) SO-239 panel-mount connector (along with some #4 hardware for mounting)
  • A 9:1 unun wound on a T130-2 toroid
  • (1) 10-24×3/4″ stainless steel screw (along with some #10 flat washers, nuts, wingnut, and lock washer)

I have to mention a few things about the parts. The PVC end-caps with flat tops are hard to find. If you search online for furniture-grade end caps, you might find some. For winding the toroid, the Emergency Amateur Radio Club in Hawaii (EARCHI) has excellent instructions you can download. 


I wasn’t sure how I was going to put this together until I started building it. So, these won’t be detailed, step-by-step instructions. They should, however, give you a general idea of how I ended up assembling it. 

  • First, I glued the two flat end caps together, end-to-end. 
  • While the glue was drying, I wound the unun. I left the leads a little longer than the EARCHI instructions, but I cut them back as needed during assembly. I used some #22 gauge solid hookup wire for the windings.
  • I drilled a 5/8-inch hole through the two attached end caps and installed the SO-239 connector. To keep things simple, I only used two screws to mount it. So, I only drilled two holes for the #4 machine screws for mounting. I also created a couple of weep holes to allow any condensation to drain out. I don’t know if these are needed or not, but they won’t hurt. 
  • I drilled a hole in the rounded end cap for the #10 screw. I made this hole a snug fit for the screw.
  • Next, I soldered the toroid input and ground connections to the SO-239. I left the toroid leads about 1.5 inches long. I used a small lug to attach the gound lead to one of the SO-239 mounting screws.
  • I then soldered a ring lug onto the end of the output wire (antenna connection) and attached it to the stainless steel bolt. I made sure that this output lead was just long enough to make the connection to the bolt. (You probably noticed a splice in this wire. I cut it by mistake, while installing the toroid. Stuff happens!)
  • I squeezed in some foam packing material on both sides of the toroid to hold it in place.
  • Finally, I press-fitted the top end cap. The end caps are on pretty tight, so I decided not to glue the parts together. With a little effort, I can still get inside of it if needed.
This is a view of the toroid. Before I closed it up, I wedged pieces of packing foam on either side of the toroid to hold it in place.
This is a view of the toroid. Before I closed it up, I wedged pieces of packing foam on either side of the toroid to hold it in place.

I don’t typically use radials with this setup, so I didn’t provide for an external ground connection. I rely on the coax shield for the necessary counterpoise. Should I ever need to, I can easily add a ground stud. 

This is a view of the bottom of the UnUn. I added two "weep holes," in case there's any condenstation inside. These probably aren't necessary.
This is a view of the bottom of the UnUn. I added two “weep holes,” in case there’s ever any condensation inside. These probably aren’t necessary.

Field Testing

I took the unun out for a test drive, and it performed as expected. With a 29.5-foot radiator and 25 feet of RG-8x coax, the internal tuner in my KX3 was able to load it up from 80M through 6M.  (This type of antenna is certainly compromised on 80M and 60M, but I have made lots of contacts with them.)

This is the weather-resistant unun in use. I used an adjustable bungee cord to strap it to the Jackite pole. The recessed connector helps to protect the coax connection from the elements.
This is the weather-resistant unun in use. I used an adjustable bungee cord to strap it to the Jackite pole. The recessed connector helps to protect the coax connection from the elements.

The Straight Key Century Club (SKCC) Weekend Sprintathon (WES) was in progress while I was out, so I made a few contest contacts. Running my usual 5 watts, I worked two French stations on 20M. I was also pleasantly surprised to have a station in Hawaii come back to my 5-watt CQ on 15M. So, it looks like it’s working. 

I also inadvertently tested the unun’s mechanical integrity. I accidentally dropped it twice before using it for the first time. No problems.


I admit I might have over-engineered this thing, but it was a fun project, nonetheless. Our first camping trip of the season is two weeks away. Hopefully, we won’t have any rain. But, if we do, my antenna will be ready for it.

73, Craig WB3GCK

More Fun with the Dollar Store Special

In a previous post, I mentioned an antenna of mine that went missing. The antenna in question was a variation of my old Dollar Store Special. After I built a replacement, I found the original in my truck. No problem; as the name suggests, it wasn’t a huge monetary investment. This antenna is just another example of what can happen with some extra speaker and too much time on my hands.

The original Dollar Store Special (circa 2005) was the first of several projects to see if I could build a usable antenna from a 50-foot length of inexpensive speaker wire. The resulting antenna was a 50-foot radiator and some counterpoise wires configurable for 40M, 30M, and 20M. I used one of these for years as a backup antenna. As with all random wire antennas, it requires a tuner and, of course, some way to get one end up in the air.

For this version, I went with a 50-foot radiator and two 25-foot radials. Besides being more simple to construct, it adds a little more flexibility. Space permitting, I can use the 50-foot wire in an inverted L, inverted V, or sloper configuration. When I need a quick way to get on the air, I can use a 25-foot radiator with a 25-foot counterpoise. (Elecraft documentation often recommends the 25-foot wires as a simple field antenna. [1][2])

My updated Dollar Store Special. In addition to this configuration, I sometimes use one of the 25-foot wires as the radiator and the other as a counterpoise.
My updated Dollar Store Special. In addition to this configuration, I sometimes use one of the 25-foot wires as the radiator and the other as a counterpoise.

I refer to this antenna—with tongue firmly planted in cheek—as the Dollar Store Special 2.0. That makes it sound like a bigger deal than it actually is. I should also note that I can no longer get speaker wire at my local dollar store. I have to spend a few dollars more now, but I kept the name anyway.

Construction is as easy as it gets:

  • Get a 50-foot length of two-conductor speaker wire. I use some inexpensive 24 gauge wire.
  • Separate the two conductors.
  • Cut one of the 50-foot wires in half.
  • I added a spade lug on one end of each wire and made a small loop in the other end.
  • I also added some Goop® sealant/adhesive to hold the end loops together and provide some strain relief to the spade lugs.

The 50-foot radiator and two 25-foot radials cover 60M through 10M using my KX3’s internal tuner. Feeding it through a 4:1 unun, I can cover 80M through 10M. A 9:1 unun works well with this length also. 

With a 25-foot radiator and a single 25-foot radial, my KX3 covers 40M through 10M with no problems. Adding in a 4:1 unun makes this a Rybakov 806 antenna that covers 60M through 10M. If you’re so inclined, you could partially unroll the 50-foot wire and use it as a second radial. 

These results, of course, are highly dependent on the tuner you’re using. There’s nothing special about the 50-ft length. You can trim the radiator back to a length that provides an easier match. I stayed with the 50-foot length since I wanted to make use of the entire pool of speaker wire for these projects. Go with whatever works for you.

I’ve had good results with both configurations, and I have been impressed with the 25-foot radiator and 25-foot radial configuration. Although it’s slightly compromised on 40M, it seems to get out pretty well. 

There’s nothing at all magical about this antenna; after all, it’s just three pieces of cheap wire. However, it makes a decent backup—or even a primary—antenna kit for portable use.

As I was writing this, I jotted down two more ideas for speaker wire antennas. Somebody stop me!

73, Craig WB3GCK

[1] Elecraft KX3 manual, “Antennas,” p. 6
[2] Elecraft AX-Line Owner’s Manual, “Operating Tips,” p. 4

Navy Radioman School – 50 Years Ago

It’s hard to believe, but a half-century has gone by since I graduated from Navy Radioman School. The Navy decided that the 18-year-old kid was ready to do this radio stuff for real. 

U.S. Navy Radioman Patch

Following three months of boot camp, the Navy transferred me to the U.S. Navy Training Center in Bainbridge, Maryland. USNTC Bainbridge was not the most glamorous place. The barracks were run-down, World War II-vintage wooden structures with a cockroach problem. 

I still remember my first day in Radioman school. The instructor gave us a sheet of paper and told us to memorize it. It was the Morse alphabet with the sound of each character. (A = DID-DAH, B = DAH-DI-DI-DIT, and so on). I also took a typing test. Fortunately, I had a typing course in high school and was able to test out of the typing training. The non-typers had to attend an after-hours crash course in touch typing.

Early on, our training focused on CW. As I recall, the requirement back then was 10 WPM, sending and receiving. The CW training also covered messaging handling, logging, and net procedures. Looking back, I think focusing on CW 8 hours a day for a few weeks was a great way to learn it. Plus, I was getting paid to do it!

We did all of our CW copying on a mill. A mill was a manual typewriter will all caps. After I got out of the Navy, I had to re-train myself to copy with a pencil since I had never done that before.

Over time, we moved on to a variety of other topics. We learned about the radio equipment we would likely be using. Radio-teletype was the primary communications mode for the fleet back then, so we also had to learn that equipment.

My diploma from Navy Radioman A School in March of 1971.
My diploma from Navy Radioman A School in March of 1971.

We spent the last week of school standing radio watches in a simulated shipboard radio room. This part of the course was called the PRAC-DECK. We set up radio circuits and sent and received message traffic. To make things interesting, the instructor would inject some equipment issues for us to troubleshoot. 

On my first mid-watch (night shift), the instructor said I had to learn the most important skill I would need out in the fleet. That skill turned out to be making coffee in one in one of those 25-cup percolators. I ran into that instructor a few years later. He laughed when I reminded him about that lesson. I told him he was right about a pot of coffee being necessary for communications. 

All in all, it was an interesting four months. Fifty years later, I’m still using the CW I learned back then. 

73, Craig WB3GCK

Antenna Testing in the Field

While other parts of the country are bracing for snowstorms, the East Coast has had a run of Spring-like weather. I took advantage of one of those days yesterday to do a little antenna experimenting.

I headed back out to the property that my daughter and her husband own. I wanted to play around with some end-fed wires that I plan to use as backup antennas. (The antennas were nothing exotic, but I’ll do a couple of future posts on them.)

I set up my equipment in one of my favorite spots and started experimenting with a couple of antenna configurations. It was a little breezy on top of the hill but nowhere as bad as it was back in January.

Field testing some end-fed wire atennas
Field testing some end-fed wire atennas

I spent most of my time playing around with antennas, but I did make some contacts. The monthly SKCC WES contest was underway, so I worked eight of my fellow members. I also heard a POTA activator in North Carolina, so I gave him a call.

I accomplished what I set out to do and made a few contacts in the process. So, I declared victory and packed up for the drive home.

One of the antennas I used today was the one that had been missing since November. This time out, I couldn’t find the replacement antenna I made up. As I was searching around in my truck for it, I found the missing original antenna. As luck would have it, I also found the replacement antenna when I got home. This time, I put both antennas in places where I’ll be sure to find them. Hopefully, I’ll remember where those places are.

73, Craig WB3GCK

My HT Go Bags

I mentioned in a previous post my obsession with bags and cases for equipment. Well, this post is further evidence of that.

Over the past year or so, I purchased a couple of new HTs. It was a long-overdue upgrade. I first acquired a Kenwood TH-D74. About six months later, I came across a deal on an AnyTone AT-D878UV I couldn’t resist. Accessory-wise (batteries, chargers, antennas, etc.), these radios are very different. So, I wanted a way to organize these accessories and pack everything for travel and ARES-RACES events.

After looking at available options, I settled on an electronics travel organizer from a company called Bagsmart. They weren’t very expensive, so I bought one for each HT. I purchased my bags on Amazon for well below the list price shown on the manufacturer’s website. The specific models available on Amazon, however, seem to come and go. 

The bag measures 9.4″L x 7.5″W x 2.8″H and is constructed of water-resistant—not waterproof—nylon. It weighs a mere 0.25kg/ 0.55 pounds. There three padded partitions that attach with Velcro that can be repositioned or removed. The bag also has a zippered mesh compartment under the lid that is great for storing cables, adapters, etc. There’s also a small compartment intended for memory cards or thumb drives. Despite its small size, it has sufficient room for everything I use for each radio. 

My HT "go bags." Several items were left out of the open bag, for the sake of clarity. I often pack a desktop charge, roll-up J-pole, a couple of spare batteries, and a hotspot for digital voice modes.
My HT “go bags.” Several items were left out of the open bag, for the sake of clarity. I often pack a desktop charge, roll-up J-Pole, a couple of spare batteries, and a hotspot for digital voice modes.

These bags have been perfect for my needs, but they do have their limitations. While they offer some protection for your radios, we aren’t talking Pelican cases here. If you need something water-tight that you can bang around on a rock, these bags aren’t for you. These are light-duty bags, to be sure. 

My only complaint with these bags is that the partitions are somewhat flimsy. Something a bit more rigid would be more to my liking. They do, however, keep things separated inside the bag. 

There’s nothing earth-shattering here, but if you need an inexpensive way to organize your gear, this bag (or something similar) might do the trick. The usual disclaimer applies: I have no financial interest in this company or their products. I’m just a satisfied customer. 

73, Craig WB3GCK

Finally Portable Again

You can tell from the lack of posts here that February hasn’t been a good month for me, radio-wise. Between the snowstorms, freezing temperatures, and family obligations, I haven’t been out portable at all this month. I set out this afternoon to change that before the month ends. 

We’re in a stretch of moderate temperatures this week here in Pennsylvania. The good news is that the snow is melting away; the bad news is that mud is replacing the snow. Coupled with a rainy weekend forecast, I set out for somewhere paved where I could hunker down in the truck. 

That quest lead me back to Black Rock Sanctuary near Phoenixville, Pennsylvania, one of my usual haunts. I used my trusty 19-ft vertical on the back and my KX3 up in the cab.

Snow melting at Black Rock Sanctuary. The rain tapered off, but there was a heavy fog off in the distance.
Snow melting at Black Rock Sanctuary. The rain tapered off, but there was a heavy fog off in the distance.

I had no particular activity in mind for today. I set out to make a few CW contacts and maybe work a POTA activator or two. Since there’s going to be a full moon tonight (the Snow Moon), I also hoped to contact some of my fellow Polar Bear QRPers.

Well, Eric VA3AMX didn’t disappoint. My fellow Polar Bear from Ottawa was my first contact. The 40M band wasn’t great, but we managed to complete the QSO. Eric would be my only Polar Bear today.

I ended up with nine contacts in my log. Among these were three POTA activators (MO, IN, OH) and a SOTA activator in Quebec. I also logged a couple of contacts with South Carolina QSO Party stations. The highlight of the outing was a QSO with OZ8X in Denmark on 30M. 

Despite the lousy weather, it felt good to get out for some portable operating. I couldn’t bear the thought of going a whole month without getting out. Hopefully, Spring is just around the corner.

73, Craig WB3GCK

My Hotspot is Back From the Dead

While trying mobile DMR last month, my (relatively) cheap hotspot experienced an untimely death. I set the hotspot aside as a future troubleshooting project.

While the Pi-Zero board appeared to be working, the MMDVM board was dead as a doornail. The OLED display was blank, and the RF side of the hotspot was non-responsive. It also wasn’t interacting with the Internet at all.

The other day, I came across a posting on a Facebook MMDVM page that shed some light on my problem. Some users reported shorts between the internal boards and the aluminum case. This tidbit of information prompted some further investigation.

I removed the top of the case, reinstalled the antenna, and applied power. To my surprise, the hotspot booted up and came back to life.
I let it run for a while without the case to verify that all was well. It was.

I noticed a solder connection that extended a little beyond the edge of the MMDVM board. It appeared to be a power connection, so I suspect that might have been what shorted. I also noticed that a single screw and the header pins are all that secure the top board. I’m guessing the board shifted a small amount while mobile causing the short.

My disassembled hotspot. If you look closely, you can see the electrical tape I added inside the top cover.
My disassembled hotspot. If you look closely, you can see the electrical tape I added inside the top cover.

To remedy this, I applied electrical tape inside the top cover of the hotspot. Not being 100 percent certain where the problem was, I covered everything except the vent openings. I used a razor blade to trim the tape around the OLED display and antenna jack openings. I also took a file to the little solder blob I had noticed. (I exercised extreme caution in doing this since I’m sometimes prone to creating new problems.)

I reassembled the case and powered it up. Voila! It still worked. Hopefully, this fix will avoid any reoccurrences and make it withstand the vibrations of mobile use.

Although you’re far more likely to find me on CW on the HF bands, I do monitor Brandmeister TG-3142 (Pennsylvania State-wide) on DMR. And, on occasion, I listen to D-Star REF20A.

73, Craig WB3GCK

Winter Field Day 2021

Plans have a way of changing in a heartbeat. I originally planned to do my usual stationary-mobile setup for Winter Field Day. A trip to visit family in central Pennsylvania nixed that plan. Then, at the last minute, an impending snowstorm caused us to cancel that trip. And just like that, Winter Field Day was on again—at least some limited participation.

Due to the last-minute change in plans, Saturday was out of the question for me. Instead, I headed out Sunday morning for a few hours. I went out to nearby Black Rock Sanctuary, one of my regular haunts. I kept things simple and went with my usual stationary-mobile setup: KX3 at 5 watts and my 19-foot vertical on the truck. I also left the laptop at home, opting for paper logging. 

WB3GCK hunkered down for Winter Field Day 2021. Although it was in the 20s outside, it was a balmy 40F in the truck.
WB3GCK hunkered down for Winter Field Day 2021. Although it was in the 20s outside, it was a balmy 40F in the truck.

I made a few contacts on 20M, but 40M was more active. So, I spent most of my time on 40M. As is my custom for Winter Field Day, I dusted off my microphone and made a rare appearance on SSB. 

I found this device in my bag and used it for a few Winter Field Day QSOs.
I found this device in my bag and used it for a few Winter Field Day QSOs.

I was out for about 2 hours until the snow started coming down steadily. I ended up with 24 WFD QSOs—19 CW and 5 SSB. My toes were getting cold anyway, so I packed up and headed home. Although it wasn’t my best showing, I did better than last year. In any event, Winter Field Day is always a fun time.

Now it’s time to break out the snow shovels and get ready for the snow storm that’s coming.

73, Craig WB3GCK

One of Those Days

Did you ever have one of those days where just about everything seems to go wrong? Yesterday was one of those days for me.

I went out to my daughter’s property yesterday to do a little portable operating. The temperature was in the low 30s (F), with a wind chill temperature down in the low 20s. Earlier in the day, my daughter cautioned me about the strong winds on the hill, my usual operating location. Despite all that, I headed up there anyway. I figured I’d hunker down in the truck and be fine.

As I was putting my vertical on the back of the truck, a strong gust of wind had me starting to regret my decision. I pressed on and got everything set up. The wind was whipping the antenna around, but everything was working fine. So far, so good. 

I started on 40M and quickly put a Canadian station in the log. I moved up to 30M and soon worked SKCC Straight Key Month stations, K3Y/5 and K3Y/9.

About that time, I looked in the rear-view mirror and saw my antenna leaning over. The movement from the wind got the top of my antenna stuck in a tree branch. I removed the 20-ft pole and laid it on the ground. I pulled my truck forward a few feet and re-installed the antenna.

My 20-foot Black Widow pole blowing in the wind. It eventually got stuck in a tree branch.
My 20-foot Black Widow pole blowing in the wind. It eventually got stuck in a tree branch.

I got back in the truck and fired up the KX3. I spent the next half hour or so trying to reach stations but not being heard. When I went out to the antenna to change bands, I found that I had neglected to connect the ground. Doh!

After correcting my oversight, I had much better luck on 20M. I worked N4CD who was activating a park in Texas. I finished up with an SKCC QSO with a station on the West Coast in Washington. 

I was mentally celebrating my coast-to-coast contact until I looked in the mirror and saw my antenna wire flapping in the breeze. Sometime during that last QSO, two sections of my pole had collapsed. That was enough for me; it was time to pack up.

But, as they say on TV, there’s more… 

I’ve been using DMR since last year, and I wanted to try going mobile. So, I brought my AnyTone AT-D878UV HT and my hotspot. I had the hotspot in the back seat, using one of the truck’s USB ports and built-in Wi-Fi hotspot. On the drive out, it worked fine. When I started the engine to head home, I noticed that the hotspot’s display was blank. It was connected to the Wi-Fi but not sending or receiving anything. 

When I plugged it in at home, I heard a brief snap. So, I think something in there got fried. I suspect there might have been a voltage surge or something when I started the truck. Doh! I guess I’ll have to start learning about Raspberry Pi and try to rebuild it one of these days. 

Looking back, I guess it wasn’t a total disaster. Despite Mother Nature and my self-inflicted issues, I still managed to put a few decent contacts in the log. I’ve had worse days, I suppose.

Here’s to better days in the future!

73, Craig WB3GCK

K1EL WKmini Morse Interface

I haven’t bought any new ham radio toys lately, so I decided to upgrade the homebrew passive CW interface I use for contesting. I had been looking at the K1EL WKmini USB keyer for a while. I recently bought one, and it fit my needs exactly.

I’m not a big contester, but for Field Day, Winter Field Day, and some POTA activations, I key the radio using macros in the logging software. For years, I used a passive interface built into a DB-9 connector, along with a USB-to-RS-232 adapter. The interface consists of a resistor and a 2N2222 transistor. It served me well, but occasionally, there were some hiccups. With this simple interface, the logging software on the laptop is doing all the CW work. Once in a while, I noticed some timing issues in the code sent.

The WKmini is based on the WinKeyer 3 chip and designed for use with contesting logging software. The WKmini takes on the work of generating the CW, so it eliminates those timing issues. The logging software sends commands and data to the keyer, and the keyer does the rest.

The other nice feature is the paddle input. This feature allows me to instantly send CW manually when needed. I was able to do this in my previous setup, but it was a bit more complicated. The WKmini keyer is a more simple, elegant approach. Its small form factor makes it ideal for portable operating.

The WKmini Morse Interface from K1EL Systems. This compact device measures 2.25" W by 1.75" D by .5" H.
The WKmini Morse Interface from K1EL Systems. This compact device measures 2.25″ W by 1.75″ D by .5″ H.

The WKmini was incredibly easy to set up. I connected the keyer to my laptop, and Windows immediately recognized it. I used the free K1EL WKscan utility to determine which COM port the keyer was using. I connected the keyer to my KX3 using a stereo patch cable with 1/8-inch connectors. Using the K1EL WK3demo utility, I was successful in keying up the radio and sending some code. 

The last thing I needed to do was to configure my N3FJP logging programs to use the WKmini instead of the old passive interface. The WKmini doesn’t have any external controls; the logging software provides the necessary settings. There is a long list of software that supports WinKey keyers, including the N3FJP suite of software. The User Manual covers the N3FJP software, which was helpful. So, with a few mouse clicks, I was in business. All of this testing and setup took less than 15 minutes.

Like other K1EL keyer products I own, the WKmini is a solid performer. I’m hoping to give this little gem a workout during Winter Field Day later this month. 

73, Craig WB3GCK