Topband: Antenna relays

[Charles Cu nningham]

Thanks, Tim!  I'd be interested to see the pics and your results with the
new relays!  I'll have a look at the Struthers-Dunn Data sheet also.  Thanks
for sharing1

 73,
Charlie, K4OTV

-----Original Message-----
From: Topband [mailto:topband-bounces at contesting.com] On Behalf Of Tim
Shoppa
Sent: Sunday, May 17, 2015 10:55 PM
To: topBand List
Subject: Topband: Antenna relays

I think I posted some details here about how I was using Omron G6RN antenna
relays (same as used in AC0HB's QEX article) for antenna switching of my
coax cables.

These are very affordable (circa $3) 8A SPDT relays and they held up OK for
me in heavy contest usage - until I got a legal limit amp. Since then I have
at first intermittent and then increasing problems especially at higher
power levels. To be fair AC0HB never conjectured that these relays could
handle legal limit!

I had guessed that the failure mode was arcing at the open contact gap, but
when I opened up a failing unit I found it was more complex. The relay is a
SPDT unit and the "common" current is carried by a super thin flexible
springy sheet conductor that also doubles as providing spring tension.
Under repeated legal limit usage it appears that heat on this conductor was
so high, the tension is no longer high enough to operate the relay reliably.

I will be constructing a new 6-way relay switch from far beefier (but still
affordable) Struthers-Dunn DPDT T92 relays - will open them up and make pics
along the way especially if I figure out how to strap them for
common-shorting-bar operation.

Tim N3QE
_________________
Topband Reflector Archives - http://www.contesting.com/_topband