[AMRadio] 24 vdc coaxial relay

Brett gazdzinski brett.gazdzinski at verizonbusiness.com
Wed Feb 7 10:22:20 EST 2007

For people with lots of gear in the shack, it really
helps to build a control box.
I built a rack mount box that has a large open relay inside
(110 volt ac) mounted on rubber standoffs, a few
small 110 vac 3pdt relays for muting with normally open
and normally closed contacts out the back, lots of switches,
lots of coax connectors, and lots of terminal strips
(screw connect) so I can select up to 4 antennas, the dummy load,
any of 8 receiver antenna outputs, up to 7 ac inputs from rigs
to key the TR and muting relays, and up to 4 high power transmitter
I also have a mod monitor takeoff built in, and a power/swr meter
output and input loop that can be in the TX side only if you want.

Its all in a small shielded rack mount box 
and is marked with what is what on the front knobs
and the back connections.

Adding or moving things around is a snap, there is
ONE huge TR relay and its quiet.

I can do instant a/b antenna tests, switch receivers or transmitters
in seconds, all from the operating chair.

And its just a bunch of switches and relays, and zillions
of coax connectors...


> ars.w5omr at gmail.com writes:
> > I think that at such a low frequency (160~80m) that if 
> you're looking 
> > for a coaxial relay, you could probably use a larger 
> contactor relay.
> Good point, but I was thinking of a coaxial relay for better 
> isolation 
> between the tx and rx ports and protection for the receiver, 
> and shielding to 
> minimize RF in the shack spraying around.  But there are 
> always options, and now 
> that I think further about it, (A) I could put the relay 
> inside the transmitter 
> cabinet, and (B) if I can find a 24 vdc contactor with DPDT 
> action I could 
> short the receiver side when the relay is in the tx position 
> for increased 
> protection for the receiver.
> Steve WD8DAS
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