4th of July Weekend POTA

It had been a while since I’ve done a POTA activation, so I did a spur-of-the-moment activation today. Valley Forge National Historical Park (POTA K-0761) seemed like an appropriate park to activate for the 4th of July weekend.

The weatherman was forecasting temperatures in the upper 90s today, so I headed straight for my favorite shady parking spot. Unfortunately, someone was already parked there. I headed off to a remote corner of the parking lot away from the picnics. There wasn’t any shade there, so I operated inside the truck. At least I would be out of the direct sunlight. I put my 19-ft vertical on the back of my truck and set up my KX3 in the cab.

WB3GCK at Valley Forge National Historical Park (POTA K-0761, WWFF KFF-0761)
WB3GCK at Valley Forge National Historical Park (POTA K-0761, WWFF KFF-0761)

Before I had even spotted myself, I got a response to my first CQ on 40M. After that, the QSOs came steadily. It only took about 15 minutes to get my requisite ten contacts. I divided the rest of my time between 40M, 20M, and 30M. 

Even with all of the windows open, it got pretty hot inside the truck. I also noticed my KX3 was getting pretty warm, so I decided to wrap things up and head home. After an hour or so, I had 31 contacts logged, including one park-to-park QSO. 

I hope all of my U.S. friends had a happy and safe 4th of July holiday weekend.

73, Craig WB3GCK

Boschveldt QRP Field Day 2021

Boschveldt QRP Club patch

Once again, our loosely organized group of QRPers got together for Field Day. We only get together a few times each year, so our Field Day tends to be a laid-back social affair.

This year marked our 5th year operating from the property of a local business owner. We certainly appreciate him allowing us to set up camp in his field again this year. We ran as category 4A EPA using the club’s callsign, W3BQC.

Yours truly, WB3GCK, operating CW from my tent
Yours truly, WB3GCK, operating CW from my tent

This year’s Boschveldt crew included: 

Ed WA3WSJ
Ed K3YTR
Glen NK1N
Ron WA8YIH and his son, Cole
John NU3E
Rob KE3TI
Craig WB3GCK

Ron WA8YIH operated phone and ran CW on 80M
Ron WA8YIH operated phone and ran CW on 80M

I spent most of the weekend hobbling around on a bum knee, so I didn’t get pictures of everyone there. WA3WSJ will likely post more on the Boschveldt QRP Club website

Glen NK1N working the satellites
Glen NK1N working the satellites

I operated on 40M only with a 53-ft inverted L. I gave my new K1EL WKmini CW interface its first real workout. I have to say it performed flawlessly for me. One of the highlights for me was working W1AW.

KE3TI operating CW. Rob joined us for the first time this year.
KE3TI operating CW. Rob joined us for the first time this year.

I think it’s safe to say that none of our group are hardcore contesters. We just enjoy camping together and playing some radio. I haven’t received everyone’s logs yet, but I’m sure we won’t be leading our category. Nonetheless, it was a good time. 

Ed K3YTR operating 2M and 6M SSB and FM
Ed K3YTR operating 2M and 6M SSB and FM

Weather-wise, it has a hot and humid weekend. We had some rain Saturday afternoon; thankfully, it didn’t last long. Overall, it was far from the worst weather we’ve endured for Field Day.

Fueling up for the day at the Boschveldt QRP Club Field Day
Fueling up for the day at the Boschveldt QRP Club Field Day

Our next major group outing will be in January 2022. We’re planning to have our annual Winter get-together at the Daniel Boone Homestead

I hope everyone had a successful and safe Field Day.

72, Craig WB3GCK

Inside My Old Tuner

In a recent post, I wrote about an old antenna tuner I built about 25 years ago. Although a description of it has been online for decades, I never posted pictures of it. So, here it is. 

I originally posted an article about this tuner on my QSL.net website under the title: A Simple and Flexible Tuner for QRP. Once my go-to transmatch for portable use, it had been on the shelf for quite a while. I hadn’t opened the case in 20 years, so it was a nostalgic walk down Memory Lane for me. 

Schematic of the "Simple and Flexible Tuner for QRP."
Schematic of the “Simple and Flexible Tuner for QRP.”

All of the parts used for this project came from my junk box or were re-purposed from other projects. This is the second tuner to inhabit this enclosure, so the variable capacitor and rotary switch were already in place. 

The coil is consists of 40 turns of enameled copper wire on a plastic 35mm canister. The wire appears to be 22 AWG. I wasn’t shooting for any particular inductance value; I just started winding turns. Based on the dimensions of the coil, the total inductance appears to be approximately 31 uH. I tapped it in 8 places and wired it to a rotary switch. I used two-sided foam tape to secure it to the bottom of the enclosure. I left the cap on the film canister so that the lid would press down slightly on it. This helps to securely hold the coil in place.

Inside view of the tuner
Inside view of the tuner

The variable capacitor was salvaged from an old radio by a friend of mine. It’s a two-section capacitor, totaling about 365 pf, according to my notes. I added a switch to select between one or both of the sections. Because the capacitor is sometimes in series with the coil, I used some thin fiberglass material to insulate it from the chassis. 

Front panel of my old antenna tuner. The switch selects one or both sections of the variable capacitor.
Front panel of my old antenna tuner. The switch selects one or both sections of the variable capacitor.

To the best of my recollection, I purchased the aluminum box at Radio Shack back in the day. I finished off the project with some embossed labels made on an old Dymo label maker. They look tacky, but they’re still holding up after all these years.

Rear view of my old tuner. The slide switch on the left selects the confiuration. In the "LO" position, the coil and capacitor are in series. In the "HI" position, the tuner is configured as an L-match tuner.
Rear view of my old tuner. The slide switch on the left selects the configuration. In the “LO” position, the coil and capacitor are in series. In the “HI” position, the tuner is configured as an L-match tuner.

After spending 15 or more years on the shelf, this funky-looking tuner has been seeing a lot more use lately. I mostly use it as an L-Match for end-fed wires. (I’ve only used the low impedance, series connection a few times over the years.) It’s a great portable tuner for QRP when weight isn’t a consideration. 

I have the parts on hand to build a lighter L-match when I need to carry a tuner in my backpack. Until I find the time to put it together, I’ll keep using this funky old tuner.

73, Craig WB3GCK

Old Tuner to the Rescue

According to the weather prognosticators, today is the start of a 4- or 5-day heatwave here in southeastern Pennsylvania. So, I wanted to get out early for some antenna testing before things heated up too much.

I planned to play around with the speaker wire end-fed halfwave antenna I built recently. To do this, I went back to my favorite antenna test range—my daughter and son-in-law’s property. 

I set up the formerly 66-foot wire (now about 63 feet) in an inverted-V configuration. Since the last time I used this antenna, I trimmed off a couple of feet to see if I could get my little Hendricks SOTA tuner to load it on 20M. 

I started with the SOTA tuner on the 40M band and worked a POTA activator in Indiana. I moved up to 20M, but the SOTA tuner wouldn’t tune below a 2.2:1 SWR. 

Before I left the house today, I had the forethought to pack an old antenna tuner I built about 25 years ago. I used it extensively years ago, but I relegated it to the shelf when fancier equipment came along. I switched to the old tuner, which I configured as an L-match. It loaded up nicely on 40, 20, and 15 meters. As a bonus, the old-school tuner gave a good match on 30 and 17 meters. 

My 25-year-old homebrew antenna tuner. It doesn't look like much, but it did a nice job with my end-fed halfwave antenna cut for 40M.
My 25-year-old homebrew antenna tuner. It doesn’t look like much, but it did a nice job with my end-fed halfwave antenna cut for 40M.

After I finished experimenting with the antenna, I set out to make a few contacts. It was a busy day for Parks-on-the-Air (POTA) activators. I worked 10 of them in 8 states plus Puerto Rico. Three of the QSOs were on 17 meters. It was nice to hear POTA activity up there. 

All in all, I was pleased with how my old homebrew antenna tuner performed. I don’t think it will be spending as much time on the shelf in the future.

73, Craig Wb3GCK

Memorial Day 2021

I was out of town visiting family for most of the weekend. However, I managed to get out for a brief QRP-portable outing this afternoon.

I headed back up to my daughter’s property and set up on top of a hill. The ground was a bit muddy from recent rains, so I set up in my truck. I set up my KX3 in the cab and mounted my 19-foot vertical on the back.

WB3GCK operating portable on Memorial Day 2021
WB3GCK operating portable on Memorial Day 2021

I started with an SKCC QSO on 40M with KG4GCX in North Carolina. I also had a chat with K4VSV in South Carolina. Bill was running 10W and was pounding into southeastern Pennsylvania.

I spent the rest of my time hunting for CW POTA activators and managed to work 5 of them: WD5GRW in Texas, K7CO in Utah, NG5E in Oklahoma, KD8IE in Ohio, and WB0TUA in Michigan. Thanks to these folks who took the time on a holiday to activate parks.

I hope all of my U.S. friends have a safe and enjoyable holiday. Please take time to remember those who made the ultimate sacrifice to defend our freedoms.

73, Craig WB3GCK

Speaker Wire EFHW Antennas

A while back, I challenged myself to see what kind of antennas I could make from a cheap 50-foot roll of two-conductor speaker wire. This time I made a couple of end-fed halfwave wires for the 40M and 20M bands. 

My aim with these projects is to make (nearly) full use of the 50 feet of speaker wire. I figured that would be enough for 66-foot and 34-foot radiators for the 40M and 20M bands, respectively. These dimensions work with the Hendricks SOTA Tuner (now sold by Pacific Antenna) I planned to use with them. 

Construction couldn’t be more simple:

  • Starting with 50 feet of speaker wire, separate the conductors.
  • Cut one of the wires into two lengths, 34 and 16 feet.
  • Splice the 16-foot wire onto the 50-foot wire. Now you have wires that are approximately a halfwave on 40M (66 feet) and 20M (34 feet).
  • I added spade lugs to one end of each wire. 
  • I used pieces of a used gift card to make end insulators that would allow for adjustments if needed. (See photo)
Speaker Wire EFHW Antenna diagram
Speaker Wire EFHW Antenna diagram

Of course, you’ll need an antenna coupler to match these wires to your rig. The SOTA Tuner I used worked fine, but each wire operated only on a single band. I cheated a bit and used some other scrap wire to make two short counterpoise wires, 5 feet for 40M and 3 feet for 20M. Of course, you could always use the 34-foot wire as a counterpoise for the 66-foot wire if you’d like. 

An improvised end insulator made from an old gift card. I used this so I could shorten the wire, if needed, by folding it back on itself.
An improvised end insulator made from an old gift card. I used this so I could shorten the wire, if needed, by folding it back on itself.

I haven’t tried it yet, but an L-network transmatch should allow the 66-foot wire to work on 40M, 20M, and 10M. A 49:1 transformer might also give you multiple bands with the 66-foot wire. You’ll likely need to adjust the length to obtain a match. You’re on your own here.

In the field, the SOTA Tuner provided a good match on both wires. I used the 66-foot wire as an inverted vee and the 34-foot wire as a sloper. I had no trouble making contacts on both bands with 5 watts.

Of course, you could build these antennas with any old wire. After all, it’s just wire. But, I enjoy the challenge of being constrained by the 50 feet of speaker wire. 

I have more speaker wire and more antenna ideas, so you’re going to be subjected to more of these crazy projects in the future.

73, Craig WB3GCK

Summer Weather Preview

The temperature climbed into the 80s (F) today, giving southeastern Pennsylvania a taste of the warmer weather to come. It seemed like a good day for some QRP-portable operating.

I had a couple of end-fed halfwave (EFHW) antennas I built last night that I wanted to try out in the field. So, I headed out to my daughter’s property and set up on the top of the hill. I set up my KX3 on a small table and set up a 40M EFHW antenna as an inverted vee. (I’ll do a separate post on these antennas.)

Taking advantage of the warm weather today
Taking advantage of the warm weather today

The band was somewhat noisy. I suspect it was coming from the power lines that cross the property. Undeterred, I started calling CQ on 40M near the Straight Key Century Club (SKCC) calling frequency. I soon received a call from WA2JMG in New York. Pete was operating outdoors from his deck.

Next up was a two-way QRP SKCC QSO with WN1MB in Connecticut. Jeff was running 2 watts and cutting through my local noise. I finished up on 40M by working a New England QSO Party (NEQP) station in Maine.

At this point, I took down the 40M wire and replaced it with a 20M EFHW configured as a sloper. Thankfully, the noise was slightly lower on this band. When I wasn’t playing around with the antenna, I worked a couple more NEQP stations.

At this point, I had lost my shade and had the sun beating down on my neck (and the KX3). It seemed like a good time to pack up and head home for lunch.

I’m looking forward to more weather like this. Next time I’ll set up in a spot with more shade.

72, Craig WB3GCK

First Camping Trip of 2021

We kicked off our 2021 camping season over the weekend. Although we had a few issues with the QRP Camper, we had a great time nonetheless.

As is our usual practice, we headed up to French Creek State Park near Elverson, PA, for our first trip. It’s close to home and a good place for our shake-down trip. It’s also a convenient location for our grandkids to come and hang out at the campsite. 

Radio-wise, I used my trusty Elecraft KX3 and a 29.5-foot wire vertical. I fed the vertical wire through the weather-resistant UnUn I built recently.

After getting things set up, I tested the antenna and had a Straight Key Century Club (SKCC) QSO with a station in Michigan. Convinced that everything was working, I headed out to enjoy the campfire on a chilly evening.

The "QRP Camper" at French Creek State Park
The “QRP Camper” at French Creek State Park

On Saturday, I decided to do an impromptu Parks on the Air (POTA) activation before all of the grandkids showed up for the day. Marginal cell phone service precluded me from spotting myself. So, I moved 1 KHz up from another POTA activator, hoping someone would stumble across me while looking for him. I got off to a slow start, but eventually, things picked up. I’m assuming some kind soul spotted me. I stayed on 40M and worked about 19 stations in an hour or so. 

Later in the day, I checked the bands and worked, WA1WCC from Cape Cod. WA1WCC was commemorating the Chatham Radio/WCC coastal station for International Marconi Day (IMD). I also heard Steve K0BWR activating a park in Missouri. Conditions were rough, but Steve hung in there with me to complete a park-to-park QSO. By this time, contest stations had flooded the band, and there was heavy static from rain headed towards us. So, I pulled the plug for the night.

Speaking of rain, my weather-resistant UnUn got its first real test in wet weather. We had about six or seven hours of steady rain overnight, and the UnUn came through unscathed. 

My weather-resistant 9:1 UnUn after 6 or 7 hours of steady rain. It came through unscathed.
My weather-resistant 9:1 UnUn after a night of steady rain. It came through unscathed.

Before packing up on Sunday morning, I finished the weekend with a chat with Bob N4QR in North Carolina. Bob was using a homebrew 3-tube transmitter, and it sounded great. He said he was using a DX-160 receiver, which was the receiver I used back in my Novice days.

I have a few minor repairs to do on the camper before our next trip, but it sure felt good to be camping in it again. 

73, Craig WB3GCK

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.

Parts

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. 

Construction

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.

Conclusion

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

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