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Re: Topband: Arching Prevention

To: <topband@contesting.com>
Subject: Re: Topband: Arching Prevention
From: "John Kaufmann" <jkaufmann@alum.mit.edu>
Reply-to: jkaufmann@alum.mit.edu
Date: Wed, 09 Nov 2005 21:45:31 -0500
List-post: <mailto:topband@contesting.com>
Tom Rauch wrote:

> I may be missing something, but I don't get it.......

I made a typo that was confusing and erroneous.  I fixed that.

> You still have the full 160 meter vertical's base voltage
> from one contact to ground when on 160.

>From Bob's description, it sounded like his problem was arcing across his
"unused" 80m relay contacts (which are at best a few millimeters apart)
during 160m operation with the loading coil.   It's no wonder there is
arcing with up to a few thousand volts across a few millimeters.  I
suggested a different relay configuration that doesn't put high voltage
across close-spaced contacts.  It does rely on spatial separation of the two
relay poles, which should be much greater in any reasonable relay (at least
the ones I use).

There is still a potential for insulation breakdown but I have yet to see it
in the relays, at least not after fixing the other problems (especially
moisture).  As I described it I do occasionally see it in the SO-239
connectors, which are the now weak point in my system.  I suppose the
solution here is to use some other connector type.

73, John W1FV

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