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Suggestions for 9:1 unun install

338_MtRushmore

338_MtRushmore

Sr. Member
Jun 17, 2012
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The Dakotas
I haven't played radio in a few years, and now live in an hoa neighborhood. 2 story house 100' square lot with radio in the basement. I was thinking about running a wire over the house and to a tree. The radio room is under the house end of the red "wire" in the pic. I could run coax out the bottom side of the house to use shield as a counterpoise, but I couldn't get as much wire up and half the antenna would be in the basement. I'm trying to figure out a ground/counterpoise or something. There is a vinyl chainlink fence around the backyard now, but I dont think it would be much help.

Anyone have any helpful ideas? (Other than endfeds suck and talk to toasters and such)

20201004_122934.jpg
 

How about ground mounted radials? I scapled the grass and put down radials with biodegradable landscape spikes. The grass grew over them and I can't see them anymore.

Then choke the hell out of the coax to keep rf out of the shack.
 
Since there was no replies, I figured none had ever used anything other than coax shield. I was thinking about trying a ground rod first for what should be the worst reference. Then maybe running a wire or 2 in the front and back yards.

I really have no idea what might work best. I've only seen counterpoise underneath and 180 away from the wire.
 
338: Good to see you back. A few thoughts.
Can you supply any better pictures, specifically of where the wire(coax) comes out side?
You must have a external tuner, I am guessing.
First thought would be a Remote operated tuner.
Secondly, if you have already a decent size tuner with balanced output terminals.
Then this thought, run 2 coax's like copper shielded RG6 from tuner to the outside point to be used as (parallel feeders) from the balanced output of the tuner. The one side goes to the wire, other goes to ground rod with attached counterpoise wires. You would be using the center conductors on both. Counterpoise wires several fanned out towards the front yard (30 to 60 ft. long/IF possible) Then another towards the back yard till it clears the house, then attach another group fanned out across the back.
The one towards the back yard say #10/#12 size then the attached wires could be small #20 making it easy to conceal and manage. The wires going toward front could all be small gauge. The common point of attachment being the ground rod and the second of the paired coax. The shields would tie together at both ends but not attached. Multiple Ferrite clamp style beads could be installed at both ends.
Id5ER.jpg

Forget the wording(Receiver = Tuner Output)
(Sensor = Counterpoise - Ground +Wire over home)
My 2 Cents, I am forgetting the 9:1 and looking at a different (possibly better?) options.
All the Best
Gary
 
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. In short, an NVIS needs to be .15 to .25 wavelengths above ground for good performance. Yes, one will work just a few feet above ground and will be quieter than one higher up, but at what cost? Quieter simply because of ground losses.

my OCF at 36 feet above ground is perfect for NVIS and local qso's up to 300 miles.
Further contacts are possible but NVIS is very good.
I use vertical antenna's at 160-20 with low angle take off for continental/world wide qso's.
Here at the higher frequencies the OCF starts to work as dipole as well, though on every band from 160 - 10 i have verticals working also.
 
I have never installed a radio at this qth, so I have to start from scratch. I had never thought about feeding the unun with balanced line, but the little bit I used it in the past it tuned fine internally.

I'm currently on the hunt for a 1000+ tuner, although I have a feeling I'd never be able to use much power here anyways.
 
So far the best way to install counterpoise wires I've found, uses a Skill Saw, friction blade and a variac. The friction blade cuts through rock and roots without bucking and the variac slows it down enough so your not shooting dirt and dust everywhere. The variac can be replaced with a China virus mask and garden hose to wash any extra dirt off the lawn.

Tuck your wire in the slot with something like a paint stir stick, just below the surface and step on the dirt to compress it closed again. When you're done, no one will even notice if they didn't watch you. For years I was using a garden edger to cut a line in the lawn. Needless to say, this saves some time and prevents blisters on your foot.

If you're willing to put a good counterpoise system in the ground and use a short ground strap to bring it to the back of a tuner in the basement, don't be afraid of the end fed. Being in the basement makes this type of counterpoise installation and connection ideal. You really don't have the spot to put a low profile, balanced antenna up for 80 so this could work well.

The idea to run coax to the roof has its pros and cons. Doing so should reduce RFI in the house where the wire runs up, but you still have the downward radiation from the horizontal span right on the roof anyhow. Eliminating any feedline will increase signal and add some vertical component with omni coverage. On the other hand, using coax may also reduce receiver interference from other devices in the house.

The simple solution is to give yourself both options by running the coax. You still want your ground strap connected directly to the tuner. But, now you can remove the PL-259, short both conductors together and connect them to the end fed terminal of the tuner. You can even make an adaptor with two connectors and a short piece of coax that only connects the center conductor to both on the coax coming from the roof.
 
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I've read a lot on using a 9:1, and obviously there are many conflicting claims. The only consistency I find is to mount the unun near the ground.

There seems to be 4 methods used with these.
Elevated counterpoise at least 40' long, several different lengths are better
Radial field, the more the better.
Using coax shield 25' minimum
Using ground rod only

These should be in order from best to worst. Is there a reason not to use elevated counterpoise around the side of the house? I don't think they have to be large diameter so I would think I could hide it under the lip of the siding and out to the deck.

I'm also seeing it stated that counterpoise should run perpendicular to, or 180 from the antenna wire. If this is true it seems like elevated is a good option.
 
Elevated radials are good. If you're trying to hide them remember that there is current flowing on the wires as well as high voltage points. Be mindful of where you put them.
 
543_Dallas said:
Elevated radials are good. If you're trying to hide them remember that there is current flowing on the wires as well as high voltage points. Be mindful of where you put them.
Click to expand...
After further reading I think rf burns are the only real danger, and running the counterpoise in a pvc pipe should eliminate that. Is this what you were thinking, or is there more to it?
 
Having exposed wire at the tip of a dipole where you know there is high voltage is kinda silly if you think about it. I fail to see a way to eliminate the danger without eliminating the rf. Anything more than double insulating the counterpoise would add much more danger in my situation.
 
Thanks for the report. My Ryobi charger is a static machine also. I figured that's what I got for being cheap but I guess the better brands have the same problems.
 

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