Eric Rosenberg wrote:
> My noisy urban lot is small (40x140), and the Pennants are awfully close
> to the TX antenna. (inv-l's on 160 and 80, 1/2 square on 40).
>
> I need to decouple the TX antenna when listening on the Pennants, but am
> not quite sure how to do it.
>
> Eric,
>
> Thanks for the frequent DC multipliers in various contests. Before embarking
> on elaborate switching you might do a few test to see how much random noise
> is contributed by the Inv L's to your RX antennas. Having an old fashion
> porcelin knife switch (like we had on the farm in North Dakota to turn on the
> milking machines) may be available or you could build one with fiberglass
> strips and copper flashing pieces....and have an assistant do the switching
> while you are listening. Opening up the fed point match or grounding either
> end or both is worth a try. I think the far end of your Inv-L is close enough
> to the ground to reach with a "earthing" connection. Also a lot may depend
> on common mode rejection to the pennants feedline. Insertion of toriods or a
> ground isolated 1:1 balun may even help taking down the noise pickup on the
> coax itself. If you find that there is indeed noise from the TX which common
> mode isolation can not cure then a 12VDC high current relay will be req
uired. Some have reported success with inexpensive automotive DC relays.
They can handle the current but for TX voltage I haven't any idea...as it all
depends on your feed/match system.
>
Good luck,
Herb, KV4FZ
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