Topband: Antenna relays

[Tim Shoppa]

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