A 9 to 1 UNUN for random wire matching

k0ua · Mar 1, 2017

Today I built a 9 to 1 UNUN (Unbalanced to Unbalanced) RF matching transformer to match a random length end fed wire for the HF bands. If any or all of that sounded like Greek or ancient Egyptian, I would be happy to explain it in depth.

What it amounts to is fabricating a portable "grab and go" portable antenna for worldwide HF (High Frequency) radio communications. This is not intended as a permanent antenna, but a temporary solution to portable operation. Some may question why not just build a dipole as it is more efficient? True, but dipoles as resonant antenna's are not all band capable, AND big reason is they require three supports. This requires one support. I intend to use a handy tree limb and some string.

Preppers take note: This antenna and some string, and your 12 volt DC powered HF radio and a battery and perhaps a folding solar array to charge it equals communications.

I checked out all the connections with and ohm meter and all elements of the device show a dead short as they should. I will try out this device Soon, weather permitting and we shall see how well it works (or not.:shocked

. I have never built one of these before. I have about $30 in the whole thing including about 30 foot of coaxial cable. The most expensive part being the coax.

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ovrszd · Mar 1, 2017

Looking at the backdrop, I think you are the "prepper" James!!!!

Anxious to hear how this widget works. You are functioning way above my paygrade!!!!

k0ua · Mar 1, 2017

ovrszd said:
Looking at the backdrop, I think you are the "prepper" James!!!!

Anxious to hear how this widget works. You are functioning way above my paygrade!!!!

Well the old Sierra bullet mat is just my work surface on the electronics workbench

. Now if you had been in the signal corps all of this would seem like old hat. On the last contest I worked, one of the guys produced an army surplus portable mast consisting of 4 foot sections and a tripod base made of the same sections. We popped up this mast in no time with an OCFD in an inverted V configuration and used a handy telephone pole to tie off one end and a fence for the other.. It worked quite well. Those army surplus quick up portable mast antenna supports are well thought of. Probably cost the government a fortune..

BukitCase · Mar 1, 2017

Ahh, the SENSIBLE version of the "Sierra Club" :laughing:

Whatsa matter, James - a 3-wire Rhombic too much challenge to "portable-ize"???

...Steve (Much less TUNE...:=)

k0ua · Mar 1, 2017

BukitCase said:
Ahh, the SENSIBLE version of the "Sierra Club" :laughing:

Whatsa matter, James - a 3-wire Rhombic too much challenge to "portable-ize"??? ...Steve (Much less TUNE...:=)

Yeah, Rhombics are a bit much...

k0ua · Mar 2, 2017

OK, first test for a few minutes this afternoon. I worked KB3IHX Steve in Pennsylvania on SSB (Single Side Band) for a fairly long QSO (conversation) where we exchanged signal reports of 58 on both ends. This was on 20 meters. I was able to make the antenna tune with the built in very limited antenna tuner in the Yaesu FT-450 on all bands from 20 meters thru 6 meters. But was unable to to tune 40 or 30 meters. 40 meters was the actual band I wanted to operate on most as our declining sunspot levels making the upper bands rather spotty and getting worse in the coming years.

I did try adding a 30 foot counterpoise wire and I still could not bring the SWR (Standing Wave Ratio) down to where the Yaesu could handle it. BUT I have a nice Z11pro autotuner that will run on batteries and my next experiment will be to see what it can do on 40 or maybe even 80 meters with this antenna. Its tuning range is much much broader than the tuner in the radio.

So after a long contact with Steve and calling a PY2 in Brazil in a pileup with my 25 watts and a very rudimentary portable antenna my battery went TU (Teats Up, as in dead). That battery is a "pull" from an old UPS and it is not really much good.

I heard a lot of good strong signals on 40 meters. It is hard to say how well the antenna will work overall with this one short test, but so far I have had some success. A better power supply is sorely needed, and more experimenting is in the works. 73 (best regards) to all that have read so far...

Here are some photos of today's operation:

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MossRoad · Mar 2, 2017

When I was a kid, my dad had a little Hallicrafters receiver that he got when he was young. That tree photo reminds me of when he put up a wire between two trees on springs to absorb tree movement. The trees were close to 100' apart and he somehow got each end up about 40' off the ground. Anyhow, it had a wire coming down from the middle and ran into the house. We'd listen to stuff from all over the world. He seemed to get particular joy out of hearing foreign language radio. Radio always fascinated me. We built a crytal set for Scouts and used that antenna for that, too. I went to technical college for TV and radio repair, and industrial electronics. My first job got me more towards machinery and that led to computers, so I drifted pretty far away from radio over the years. But I always enjoy reading these kinds of threads. :thumbsup:

k0ua · Mar 3, 2017

MossRoad said:
When I was a kid, my dad had a little Hallicrafters receiver that he got when he was young. That tree photo reminds me of when he put up a wire between two trees on springs to absorb tree movement. The trees were close to 100' apart and he somehow got each end up about 40' off the ground. Anyhow, it had a wire coming down from the middle and ran into the house. We'd listen to stuff from all over the world. He seemed to get particular joy out of hearing foreign language radio. Radio always fascinated me. We built a crytal set for Scouts and used that antenna for that, too. I went to technical college for TV and radio repair, and industrial electronics. My first job got me more towards machinery and that led to computers, so I drifted pretty far away from radio over the years. But I always enjoy reading these kinds of threads. :thumbsup:

You sound like you need to get your license. It is pretty easy now. No code, and you can practice the exams here on eham.

I can offer remote advice (for what that is worth) to get you set up..

k0ua · Mar 3, 2017

I was getting ready to put some batteries in my Z11pro tuner, and decided to stop and make a modification to it that I have wanted to do for a long time. Every once in a while the microprocessor in the tuner would get "confused" and hang. To reset it you would need to open the case and pull one of the batteries so that power would be removed from the microprocessor. A PITA. So I installed a toggle switch in series with the battery feed. A microprocessor hangup is not a problem if you run the unit off of 12vDC from the rear plug as you could just pull the plug, but I like to run from batteries if used in the field. And the batteries last about a year as the tuning relays are latching relays so they con't pull any current after the tuning cycle is finished. Anyway here are the photos showing the switch I installed on the back panel.

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k0ua · Mar 3, 2017

Ok, this afternoon I went back out with the external tuner and was able to get the antenna to tune on 80 and 40 meters. I made several contacts on 40 meters around the region (2:30 to 3:00PM local time) Texas, Illinois and Indiana. Which is what I would expect for that band at this time. No contacts on 80 of course because of the time of day. With the D layer of the ionosphere energized during daylight 80 is pretty much limited to groundwave due to absorption in getting thru the D layer.

I went back up to 20 Meters for a bit and talked to several folks on the east coast, (Keep in mind these contacts were all at the 5 Watt level on my end) and the last one in NC, I asked him to wait for a bit after we signed so I could pack everything up and get back to the house and fire up the big rig in the house with my beam antenna on the tower. We recontacted, and as expected the signals both ways were between 20 and 30 db better. That is a huge improvement of course. I was running 100 watts to a two element beam in the house. But still the little home made "wire in a tree" does work, even with low power.

So to sum it up, I am calling it a success, it is easy to deploy, low cost, small and light and with a simple extended range tuner, seems to tune from 80 thru 6 meters. (No 160 meters with this length of wire). So if anyone is interested in the schematic and instructions, I can send the PDF to you. I may play with it some more tomorrow after dark to test 80 meters if it is warm enough. Pretty cool and windy here today.