----- Original Message -----
From: "Tom W8JI" <w8ji@w8ji.com>
To: "Bruce" <k1fz@myfairpoint.net>; <topband@contesting.com>
Sent: Tuesday, December 04, 2012 6:24 AM
Subject: Re: Topband: F fitting adaptors
When using a Ameritron remote antenna switch with SO-239 fittings, does
anyone know a supplier for female F fitting to PL-259 adaptor ?
Thanks,
73
Bruce-K1FZ
Bruce,
IMO, you have the wrong switch. A transmitting type high-power switch is a
terrible device for receiving. The larger the relays (has a general rule)
the greater the problem, and it has nothing to do with sealed (enclosed)
or unsealed (open) relays.
High current relays are very problematic when only used at low power. The
problem surrounds the large contact area and lack of wetting currents, and
no significant voltage and current ever being applied to burn through any
film on the contact. There are hundreds of papers by relay manufacturers
or others detailing this problem, and it even occurs with brand new sealed
or enclosed relays.
The only high power relays immune to this issue are vacuum type relays.
I think you are heading for long term problems with adaptors and a
transmitting switch.
73 Tom
While Ive experienced vacuum relays having a problem on receive a reversal
of the coil wires took care of it, that was obviously a magnetising issue as
has been mentioned often over the years.
OTOH the pair of Ameritron RCS-4's Id used for up to 20+ years never had an
intermittent problem or lightning induced damage (a benefit of a big relay)
they had somewhat poor isolation due to the daisy chain sequencing design
and PC board layout and were replaced by a HB unit using sealed microwave
relays. Now they wll probably blow from lightning even with the protection
included.
I would think the Ameritron RCS-10 would be an ideal solution for a multiple
Beverage installation as the cost is reasonable considering the
alternatives.
Carl
KM1H
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