[TowerTalk] Relay Recommendations

Jim Thomson jim.thom at telus.net
Fri May 9 23:29:59 EDT 2014

Date: Fri, 9 May 2014 16:41:13 -0500
From: "Matt" <maflukey at gmail.com>
To: <towertalk at contesting.com>, <amps at contesting.com>
Subject: [TowerTalk] Relay Recommendations

I would appreciate recommendations for general purpose SPDT relays that can
be used reliably for RF antenna switching duty - it is not a hot switching
application.  I am aware that the DC & 60hz AC ratings are not necessarily
indicative of RF performance..  any experience out there?


Thanks in advance.




###  How much $$$  do you want to spend ??   IF you want 100%  bombproof  reliability,  
then use ceramic vac relays....like the gigavac   G2.... or G2 ham.   Both have identical specs..even though the 
G2 is rated slightly less..its not.    The G2 is rated for 10A  at 32 mhz.   You can order it with 12 vdc coil  or  26.5 vdc coil. 
The G2 is a SPDT relay.  You can also order it with tapped screw terminals  for the COM, NO, and NC  contacts. 
You can stuff 5 kw RTTY  through it all day  on 10m band.   If you require more power, then parallel 2 of em.
On a side note, even though the G2 has a 15 msec operate time and 9 msec rls time..when sped up, the operate and rls  times
are both 2.5 to 2.7 msecs.   They WILL  work in qsk mode in any amp.   If you do parallel 2 of em, that combo is then good for 20 kw CCS. 
You double the current rating, and you will  quadruple the power rating.

##  You can also parallel the contacts of mech relays too.  Any DPDT  relay can be made into a SPDT..by paralleling contacts....same deal,  current
ratings double..and power ratings quadruple.   3PDT relays  can also be made into one big SPDT relay. 

##  I have given up on mech relays  for outdoor use.   You only need a tiny bit of contact resistance  to have em go open on RX.    One solution is to 
1st apply  the cool-amp goop to the contacts to silver plate em.  Then  apply... conducto lube to the contacts. Then resistance drops to zero and 
reliability increases..esp on RX. 

##  I used G2 relays in the nema box on my 40m yagi..to short out the coils..to switch from CW  to SSB.   On the DE of a 3 el  F-12 yagi...  340N....
the DE is easy to get to..... but the REF and  DIR  are way out on the ends of the booms.  That’s the last place I need problems with relays ! 

Jim   VE7RF

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