Hello David,
You're not the first person to experience that! :-)
The short answer is that there is likely an atmospheric voltage gradient,
causing a corona discharge (which is making the noise). A corona discharge
emanates from sharp corners or points; the voltage builds up until it can
discharge. If you can smooth or insulate those points, you can reduce or
eliminate the noise.
It's possible that if you do that to the top antenna, the corona with then
appear on the lower one.
You could try installing a mast with a grounded, microscopically-sharp
point at the top, extending above the top beam. One made from a thoriated
tungsten TIG welding electrode is about as good as it gets. (Forget that
brushing thing that looks like a chimney cleaner! IMO, the points of the
wires are both too close together and not sharp enough.)
DISCLAIMER: I have not personally tried this, but I have knowledge and
experience in electron physics and corona discharge.
Having said all the above, the noise-causing discharge instead could very
well be an arc, such as between the coax connector's inner conductor and
shield.
73, Mike
www.w0btu.com
On Mon, Jul 9, 2018 at 5:19 AM, Rodman, David <rodman@buffalo.edu> wrote:
> First, I want to say this topic is not necessarily topband related, so if
> anyone wishes to comment about my question, please do so privately so as to
> cut down on band width. Thank you.
>
>
> Very smart people live on this list and I want to reach out to them about
> my system as they may know something about this too. When it rains, the
> top 20m antenna hears the precipitation and the bottom does not. Is there
> a way to silence this situation? More info on request.
>
>
> Again, thank you.
>
>
> ---
> David J Rodman MD
> Assistant Clinical Professor
> Department of Ophthalmology
> SUNY/Buffalo
>
> Office 716-857-8654
> _________________
> Topband Reflector Archives - http://www.contesting.com/_topband
>
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