Topband: Grounds

Mike Waters mikewate at
Mon Mar 3 12:56:44 EST 2014

Thanks for your thoughts. I looked at things here just now, and found that
(1) unplugging my amplifier's power cord and (2) disconnecting an unused
50' run of RG-213 from my main TX antenna switch drastically drops that
noise. :-)

I thought the noise pickup was somehow related to the low F/B (10 dB) of my
NE-SE Beverage. That now appears to be a different issue --to be solved
another day, since it's still considerably superior to the inverted-L for

73, Mike

On Sun, Mar 2, 2014 at 8:27 AM, Tom W8JI <w8ji at> wrote:

> I'm not saying that there's not a case for suppressing common mode as you
>> and others suggest.
> It all comes down to impedance ratios and signal levels. Any choke or
> filter is like a pi network or attenuator pad. It is ***always*** more than
> the series element alone.
> ...
>  I do have a problem here lately with RFI from an electronic fluorescent
>> ballast on 160 (10 feet from where I operate the radio), and I'm not sure
>> how it's getting into my NE Beverage. Big #43 beads on the ballast leads
>> didn't fix it. But that's another story.
> There are two forms of noise egress, common mode and differential mode.
> ...
> It seems very few people look at the system, which isn't that hard to do.

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