QRP My first Random Wire Length Antenna - A Few Questions

[D31245]

I have been doing a little reading and research and am looking to build my first end-fed random wire antenna. I have some ideas and a few questions but am also open to other ideas and suggestions.

My situation: I live in a town-home condo/HOA restricted property. The property is at approximately 460 feet of elevation and my shack is on the 2nd floor spare bedroom. My condo is all wood construction. I run QRP (ICOM IC-705) and have an LDG Z-100Plus Auto-tuner.

I will primarily be using the antenna indoors (I have some various run options) - although now that the warmer weather is here, I have the option to hang the antenna out my window and maybe slope it down. Or, there's the possibility of temporarily running it from the 2nd floor window straight-line to a tree - about 100 feet away - for Tx/Rx sessions, then take it down. I can fasten the long-wire about 6-7 feet up the tree trunk after running it from my window. This would take a longer wire run.

I will be focusing on usage in the 80/40/20 meter bands initially.

I was thinking of starting with non-resonant lengths the first one being 53 feet based of this paper (see below) then maybe try the 124.5 foot length.

Questions:

1. How long should my feed-line to the 9:1 Unun be? (I was thinking maybe 25 feet of RG-58 to use as a counterpoise? So no ground needed at the black Unun terminal?)
2. Can I get away with a 1-foot RG-58 jumper from the tuner out to the 1:1 choke, or should I heed the suggestion from the paper below and use a 3-5 foot coax jumper?

Parts List:

• LDG RU-9:1 Unun
• LDG RU-1:1 Unun (choke)
• #22 AWG silicone flexible-tinned copper wire
• 25' RG-58 PL-259/PL-259 terminated coax (recommendations?)
• 1' RG-58 coax jumper which I currently have (from tuner to choke)

My lengths are based on this article and informative video:

https://www.balundesigns.com/content/Wire%20Lengths%20for%204%20and%209-1%20ununs.pdf

Configuration (I believe the random wire goes to red and not ground in the diagram below):

Thanks for any help, tips, recommendations you can provide.

 

[popnokick]

If you'd like everything in one kit, consider this -
End-Fed Half-Wave Antenna Kit
It will however NOT handle the 80M band (which you're going to find tricky anyway with your space limitation / possible indoor installation).

 

[K6GBW]

So, the end fed non-resonant wire antenna is really a field expedient antenna that does work. It does not always work well and won't work well on all bands. The general rule is to select a wire that is slightly longer than a quarter wave of the lowest band you want to work. So, for 80m a quarter wave is around 66 feet. If you select a 72-foot wire it will work relatively well. Non-resonant wire antennas can be finicky and difficult to work with. Sometimes they will tune certain bands but have issues with others. I've had to do things like move the coax around to get them to tune some bands. They can be prone to noise, and you should plane to use a choke on the coax near the radio. Of course, they are like any other HF antenna, and they need to up rather high to work well.

Having said all that, they can be made to work. Just adjust your expectations.

 

[D31245]

Thank you @K6GBW. I started with 24 ft. wire and a 15 ft. ground wire off the 9:1 unun ground terminal, 25 ft. RG-8X coax to a 1:1: unun (near the tuner) then a 1ft RG-58 jumper to my tuner. I wasn't able to tune the antenna but did receive on 20 meters.

I will keep experimenting. My plan is to try a 53 ft. wire, then a 124.5 ft. wire per the article above - but your lengths above I may consider as well.

 

[dkcorlfla]

I had pretty good results with about 53 feet of very light weight 16 gauge aluminum electric fence wire, a home made 9 to 1 Unun with about 6 feet of counter poise at the Unun and snap on ferrite chokes placed near the Unun. The light antenna was mounted between the house and a tall pine at about a 45 degree angle. Black parcord and a light 3 pound weight with pulley near the house used to support the antenna and provide a lot of give for when the pine started moving in the wind. On the low end near the house the counter poise was close to the ground but not touching. The antenna is very hard to see because of the black cord and bare thin 16 gauge solid aluminum wire. You should be able to leave it up.

The only thing I did not like about it was we are in the process of getting the overhead power lines undergrounded but it's not done yet and I found the end fed picked up a lot of noise.

 

[K6GBW]

For an “end fed” wire you really need a 4:1 or 9:1 UNUN. A 1:1 is basically for a dipole. The thing to understand is every antenna has two halves, there’s no way around this. So when we say “end fed” it really isn’t end fed at all. It’s just really really off center fed. The coax braid becomes the other half of the antenna. That’s part of what makes them problematic. You can make them work, but it might take some tweaking to make it happen. I’d suggest looking up the Balun Designs website and look for their tutorial on end fed wire antennas. Palomar Engineers also has one. The have good information on wire lengths and UNUN types. A 24 foot wire is really way too short to work on anything but 10 and 12 meters. Since you want 80 meters you’re going to need more wire in the air.