[OT] - Possibly - Small Loop Antennas For Receive

[Joel Black-2]

I have a K3 with the second receiver and I’d like to utilize it with a receive only antenna. I have a horrible intermittent noise that I cannot identify and is heard state-wide at the upper portion of 80 m. I’m hoping a small loop antenna might help null that noise or at least a lot of it.

I know I want a small loop. Well, maybe...

I have looked at small shielded loops, small shielded mobius loops, mag loops, etc.

I have a friend who came by and once recommended that I string up a random length loop around the top of my wooden privacy fence. Some of the privacy fence needs to be repaired and/or replaced. The height of the fence is about 6’ and I could come down 12 - 16” from the top of that and run screw-in ceramic insulators. Except for the portion that’s my house, the privacy fence runs the perimeter of my back yard.

I could use this on 160 m if I don’t use a preamp or have the preamp switched out.

Whichever route I take, I’ll probably use the small preamp from Kits and Parts at the input of the antenna.

I have access to solid conductor LMR-400, I even have about 40’ of 7/8” hardline, but I want something that’s not real cumbersome. I think the mag loop may be easier to construct but none of the small loops look extremely difficult.

I am, however, a tad confused on how to couple a shielded loop to the preamp. Can I just use alligator clips and run those to the shield and both conductors? I don’t see why I could not connect a preamp at the input to a mag loop. I could take the mag loop portable with me if I wanted.

I’m just looking for some advice and if y’all think this is too far off topic, please respond directly.

Thanks.

73,
Joel - W4JBB
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[Ignacy]

You hope that the loop can null the noise on 80m. Loops have a very sharp null and will null the noise if it is coming from one direction. I am not sure that the shielded loop is much better than unshielded. Also the signal level on 80m will probably be pretty good without an amp.

I suggest that you built an unshielded loop with a  piece of wire and a tuning capacitor. Say a diameter of 5 ft. Then, you rotate the antenna by hand and see whether the noise is nulled and whether the signal strength is sufficient.

My shielded loop on 160m was a disappointement as it did not pick DX well.

Ignacy, NO9E