I recently came across a product on Etsy that caught my eye. It’s a 3D printed project box with an integrated antenna wire winder. I couldn’t resist, so I ordered one.
The box will accommodate a T-130 toroid, and the snap-on lid comes with a gasket. There is a pre-drilled hole for a BNC-F panel mount connector, and there are marks to guide drilling for the output and ground connectors of your choice. You can choose from two colors: orange or green. The vendor states that it is “UV and weather resistant.”
I like the idea of having a box to enclose the balun or transformer. My preference for portable antennas is to avoid exposed components or circuit boards.
I used mine to build a 4:1 unun for portable use in a Rybakov configuration. The unun consists of 19 bifilar turns of #24 solid hookup wire on a T130-2 toroid. You can find plans for winding the unun here and other places on the Internet. For the output and ground connections, I used #10-24×3/4″ stainless steel machine screws, along with some nuts, flat washers, and lock washers.
Inside view of the 4:1 unun. I used double-sided foam mounting tape to secure the toroid. I also use a small piece of packing foam (not shown) between the lid and the toroid for added stability.
To go along with the completed unun, I prepared two 26-foot wires; one for the radiator and one for a counterpoise. I finished up by attaching a length of 2.5mm bungee cord. This cord keeps everything together for travel. I have also used it to secure the box to a vertical support, e.g., fiberglass mast, fence post, etc.
The 4:1 unun deployed in a Rybakov vertical configuration with a 26-foot radiator and a 26-foot counterpoise
In the field, this Rybakov antenna worked as well as others I have built over the years. I tested it using my Penntek TR-35 and Elecraft T1 tuner with 18 feet of coax. It tuned up easily on 40, 30, 20, and 17 meters, and I made a couple of QSOs while testing. The integrated winder made it easy to deploy and take down.
The 4:1 unun packed up for travel
I have a feeling another one of these boxes is in my future. Maybe a 9:1 unun next time?
One antenna I plan to try during my annual Outer Banks, North Carolina, vacation this summer requires a 4:1 unun. If the antenna works as hoped, it’ll be in place for the entire week. So, I need an unun that can stand up to the elements.
About a year ago, I built a 9:1 unun in a weather-resistant housing made from PVC pipe parts. I had some parts left over from that project, so I built a 4:1 unun version. The construction of this unun is like the last one, however, this one has a ground terminal.
Weather-resistant 4:1 unun components
I wouldn’t want to take this unun on a backpacking trip; it weighs in at a substantial 8.6 ounces. When I’m going to be operating from a location for an extended period, however, this should do the trick.
Parts
The parts for the housing are similar to the last one, but there are some additions for the ground connection.
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 4:1 unun wound on a T130-2 toroid
(2) #10-24×3/4″ stainless steel machine screw (along with some #10 flat washers, nuts, wing nuts, and lock washer)
The PVC end-caps with flat tops can be hard to find. If you search online for furniture-grade end caps, you might find some.
Construction
You can find plans for winding the unun here and other places on the Internet. The one I built for this project uses 19 bifilar windings of #24 solid hookup wire on the T130-2 toroid.
To start, you need to glue the two flat top end caps together. When dry, drill the holes to mount an SO-239 connector in the center.
The underside of the 4:1 unun. The SO-239 is recessed to provide some protection from the elements.
For mechanical reasons, I added the #10-24 stainless steel screw for a ground terminal in the lower half of the connector housing. A short length of wire runs from the ground screw through a small hole and connects to one of the SO-239’s mounting screws. I installed another #10-24 screw in the slightly rounded end cap for the antenna connection.
The final assembly was straight forward. I soldered the toroid’s input wires to the center pin of the SO-239 connector. Then, I attached the toroid’s ground wire to one of the SO-239’s mounting screws.
This is how the toroid is installed in the Weather-Resistant 4:1 UNUN.
Next, I inserted the PVC pipe section into the connector housing. I then installed a ring lug on the output wire. I left the output wire just long enough to make the connection to the output bolt in the rounded end cap. Before mounting the end cap to the PVC pipe, I added some pieces of foam around the toroid core to hold it in place. Then I press-fitted all the PVC parts together.
Testing in the Field
I tested the 4:1 unun in the field recently, and it performed as expected. I used it as part of a Rybakov vertical, with a 26-foot radiator supported by a Jackite pole, another 26-foot wire on the ground for a counterpoise, and 18 feet of RG-8x coax. My little Elecraft T1 tuner matched it with no problems on 40M, 30M, 20M and 17M, the bands covered by the rig I was using. Similar 4:1 ununs I have built worked well from 40M through 6M, so I’m confident this one will, too. While I was testing, I had a couple of nice CW rag chews on 40M and 30M.
The weather-resistant 4:1 unun in use. In this configuration, there’s a 26-foot radiator and a 26-foot counterpoise wire.
Wrap-up
Like its 9:1 counterpart, this unun is probably a bit over-engineered. My weather-resistant 9:1 has served me well through several camping trips and two Field Days, so I expect this 4:1 version will do likewise. So, bring on that beach weather!
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.”
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
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.
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 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.
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.
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.
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
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.
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.
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.
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.
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 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.
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.
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.
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!
On one of the several ham radio mailing lists I subscribe to, there was some recent discussion about unusual antennas. You know—bed springs, light bulbs, and the like. It brought to mind a memorable QSO I had 27 years ago.
In the July 1993 issue of QST, Rod Newkirk W9BRD (later VA3ZBB, now SK) wrote an article about building small, multi-turn loop antennas[1]. If his name doesn’t ring a bell for you, Rod wrote the “How’s DX?” column in QST from 1947 to 1978 and coined the term, “Elmer.”
Although I never actually built one of Rod’s loops, I found the article fascinating. At the end of the article, Rod noted that he conducted his loop antenna experiments in the partially-underground cellar of his Chicago home. Remarkable!
Fast-forward to September 1993. I went downstairs to my basement shack one evening and fired up my old MFJ-9030 on 30M CW. I had three QSOs that night; one of them was with—you guessed it—W9BRD.
During our QSO, Rod mentioned that he was using one of his experimental mini-loops indoors in his shack. When I told him I was running 5 watts into my rainspout, he sent back, “Hey, if it’s metal, load it up.” According to my log, we chatted for about 12 minutes before signing.
Needless to say, that contact put a smile on my face. It was the kind of QSO I really enjoy—one with a station using an unusual set-up or operating in a unique location. I guess you could say this QSO checked both of those boxes. Not to mention that I had just worked a very well-known figure in Amateur Radio.
QSL card from W9BRD documenting our unusual QSO in 1993.
I fired off a QSL card to Rod to acknowledge our QSO and to let him know that I enjoyed his loop article. Before too long, I received a card back from Rod. His typewritten note on the back of the card continued the theme of our QSO. It read, in part: “Hey, if your XYL uses gold or silver thread for that needlepoint, let’s try loading it up, Craig.” He also wrote about his experiences with rainspout antennas, including his attempt to feed a particularly stubborn one.
Rear of W9BRD’s QSL card
From articles I have read, it’s clear that Rod had a penchant for assembling and experimenting with unusual antennas. His daughter, Amanda, once wrote: “He especially loved discovering how much of a signal he could achieve with his various objects: the coffee cans, cookie tins, piles of wire and boxes and tidbits—out of which he wrung quite magical things.”[2]
When it comes to unusual antennas, Rod was a man after my own heart. Over the past 27 years, his words from our QSO have been my mantra: “If it’s metal, load it up!”
Thanks for the inspiration, Rod.
73, Craig WB3GCK
References: [1] Newkirk (W9BRD), Rod. “Honey, I Shrunk the Antenna.” QST, July 1993, pp. 34-35, 39. [2] Newkirk (WN9PMC), Amanda. “On Being W9BRD’s Daughter.” K9YA Telegraph, Vol 11, Issue 9, September 2014, pp. 2-3. (K9YA Telegraph website)
I’ve been intrigued by the half-square antenna for some time now. I don’t have the real estate to put one up at home, so I built one for portable use. Like my other speaker wire projects, this antenna is built from a 50-foot length of cheap, two-conductor wire.
You can think of the half-square as two quarter-wave verticals spaced a half-wavelength apart. It provides some gain over a quarter-wave vertical and has a low take-off angle. The half-square has a bi-directional pattern with lobes broadside to the antenna and nulls off of the ends.
Normally, the half-square is fed with coax at the top of one of the vertical elements and functions as a single-band antenna. The coax should be kept perpendicular to the vertical leg, to avoid interaction. That arrangement, however, would be somewhat awkward for a portable antenna.
For expediency in the field, I went in a different direction. I decided to feed it at the bottom of one of the vertical legs, which is a high impedance point. I use a 9:1 unun to reduce the high input impedance to something easier for a tuner to handle.
I designed this antenna for the 20M band, but I wanted to use it on other bands as well. By using the 9:1 unun to feed the bottom of the antenna, I’m able to squeeze some more bands out of it. A tuner is required, of course.
Refer to the accompanying diagram to help make sense of the following steps.
Separate the speaker wire into two 50-ft wires
On one of the wires, install a spade lug at one end. This will be the connection to your matching device)
From the spade lug, measure up 16′ 7.2″ and make a small loop using two small zip-ties.
From the second wire, cut a length that is about 16′ 9″ or so.
Strip and splice the smaller wire to the end of the larger wire. After soldering it, I covered the splice with heat-shrink tubing.
Next to the splice, make another small loop, using two zip-ties.
At the end of that wire, twist the wire to form an attachment loop. When you do this, make sure you have 16′ 7.2″ from the splice to the attachment loop.
I applied some Goop® adhesive to the loop at the end of the wire to hold it together. I also added Goop® to each of the other attachment loops.
As is my usual practice, I added some Goop® to where the wire enters the spade lug to add some strain relief.
At this point, the antenna is finished. You can, however, cut the leftover wire in half to make two radials for 20M (approximately 16 feet, give or take). I installed a spade lug on each of these wires and twisted the other ends to make a small loop. You guessed it; I put Goop® on these wires, as well.
This photo shows the splice and one of the mounting loops used in the Speaker Wire Half-Square.
Matching
[Update (6/17/2020) – After initially publishing this post, I received some great feedback from readers. As a result, I have updated, clarified, and expanded this section.]
For my first couple of outings with this antenna, I used a 9:1 unun as a quick and dirty way to get it on the air. I run about 18 feet of RG-8x coax from the unun to the radio. There’s nothing particularly critical about the coax length, but I would recommend a minimum of 16-feet for 40M and up. The exact length of the radials isn’t critical either since they’re laying on the ground. In fact, you can probably use the antenna without them. In this case, you’re relying on the coax shield for the counterpoise.
While the 9:1 worked fine, there are more efficient ways to match this antenna. I plan to continue experimenting with other methods to match the high-impedance input on 40M and 20M.
I haven’t tested them myself, but the end-fed halfwave tuners from Pacific Antenna and QRPGuys should work on 20M and 40M. They use a parallel resonant circuit and are designed to match an end-fed halfwave (EFHW) antenna.
An EFHW transformer, like the ubiquitous 49:1 transformer, should also work. You will likely need to do some pruning on the antenna to get the SWR where you want it.
Finally, a simple L-Match antenna tuner with a tapped inductor in series and a variable capacitor across the output looks like it may be the best solution for me. It should handle the high impedances on 40M and 20M, and work on other bands like a random wire tuner. This will definitely be part of my next round of experiments.
Deployment
Deploying this antenna is a snap and takes me about 5 minutes. I use two collapsible poles to support it. I attach one corner to a partially-extended 28-foot Jackite pole. The feed point of the antenna is about 3 feet off the ground.
These are the two poles I used to support the Speaker Wire Half-Square. Unfortunately, the wire is too thin to be visible in this picture.
I use a 20-foot Black Widow pole (actual length about 19.5 feet) to support the other end. I support this pole with an appropriately-sized screwdriver shoved in the ground. The handle of the screwdriver fits snugly inside the bottom section of the pole. After attaching the other corner of the antenna to top of this pole, I extend the pole and remove the bottom cap. Next, I walk the pole back until the horizontal section is taut. Then, I just shove the screwdriver in the ground and place the pole over it.
With appropriate trees nearby, you might be able to eliminate one or both of the poles. I’m not usually that lucky.
Results of Field Testing
I was pleased with the results of my initial field tests with the half-square. The internal tuner in my Elecraft KX3 was able to load the antenna from 80M through 6M. (Since the antenna’s input impedance is low on 80M, I wouldn’t recommend using the 9:1 there.) The SWR was 1.2:1 or better on all bands with the tuner.
During my first outing with the half-square, I was able to make contacts on 40M, 20M, and 15M at 5 watts with no difficulty. The antenna is a half-wavelength on 40M, and it appears to play well on that band. I had numerous Reverse Beacon Network spots on 40M showing a signal-to-noise of 20db or better.
I also used it in the field during a recent QRP contest with similar results. Signals were strong on 40M, and I worked Georgia and Quebec on 20M.
This was hardly a rigorous scientific evaluation, but I’m happy with this antenna so far. One of these days, I’d like to do some modeling to see what the radiation patterns look like on the various bands. In the meantime, I’ll do some more experimenting with impedance matching.
Wrap-Up
This was an easy and fun project. It certainly made good use of a roll of cheap speaker wire. After using this antenna in the field a couple times, I have officially added it to my arsenal of portable antenna options.
Like many of you around the world, I’m under a stay-at-home order, due to the pandemic. Taking advantage of my new-found spare time, I decided to take care of some overdue antenna maintenance.
I’ve been using my rainspout as my main antenna at home since 1993. It’s a compromise antenna, but it has given me a way to get on the air from my real estate-challenged home. Normally, I do some routine maintenance on it annually, but I’ve been lax lately. It’s been about two years or more since I’ve cleaned up the connections. This was the perfect time to get caught up.
My normal maintenance routine is to re-do the connections at the downspout. The connections are subject to exposure to the elements on the outside and rainwater coming down the inside. The downspout is on a south-facing side of the house, so the sealant on the connections also takes a beating from the sun.
Sometimes, my maintenance reminder is when I notice a change in antenna performance. Typically, it’s a change in the tuning. I might notice, for example, problems loading up on one or more bands. This time, it was an increase in noise levels.
So, I headed out to the downspout and removed the screws I use to make the connection. I had to scrape off enough of the sealant I use to get a screwdriver in there. Next, I took some light sandpaper and sanded around the connection points. A few times over the years, I drilled new holes for the connections. This time, I just needed to clean things up a bit.
I use two ring lugs, jumpered together, to make the connections (see photo). My rationale is that two connections are better than one. If needed, I replace the ring lugs and the screws, but this time, they were still in good shape. I just cleaned them up a bit and reinstalled them. I finished up by resealing everything with a generous amount of Goop® sealant/adhesive.
This is the connection to the downspout. Two ring terminals, jumpered together, are used to ensure a good connection. I used a liberal application of Goop sealant to weather-proof the connections. (A second coat was applied after this picture was taken.) You can see some holes from previous connections. (Note to Self: Do some touch up painting on the downspout!)
Next, I moved indoors and turned my attention to the ground connections.
I have a 1/2-inch copper pipe that I use as a ground bus for my station. The pipe runs across the back of my radio desk to an incoming cold water pipe about 6 feet away. I use hose clamps and braided strap to make the connections to it. The 1:1 unun that feeds the wire out to the downspout is also grounded to the pipe with a braided strap and a hose clamp. The pipe itself is connected to the incoming water pipe with hose clamps and a short braided strap.
I couldn’t remember the last time I cleaned up these connections, so, it was time to get busy. I removed the connections to the copper pipe ground bus and cleaned up the pipe with light sandpaper and steel wool. I reinstalled everything, making sure the connections were tight.
Turning on my transceiver, I was pleasantly surprised with the fruits of my efforts. My local noise levels have always been high, and 40M has been the worst lately. The noise was S5 or S6 at times, but now it was down to S1 or S2. The noise on 80M was also an S unit or two lower.
One of the ground connections at the operating position. The braid strap goes to the ground terminal on my 1:1 unun. The other end of the copper pipe ground bus uses hose clamps and a short piece of braid to connect to the cold water pipe coming into the house.
I wish I had taken care of this maintenance sooner. Next time, I’ll try not to procrastinate.
Stay safe in these difficult times. I’ll see you on the air.
WB3GCK QRP Amateur Radio 