[Amps] Best source for Gigavac GH-1 ?

[Larry Benko]

Jim,

What is failing on the relays?  Is it the coil opening up, the contacts 
sticking, the receive side contact appearing open, or the pivot getting 
sloppy and the contacts bouncing too much?  I have tested many relays 
for mechanical life (low current in the contacts) in previous employment 
and many exceed 20 million cycles.  All the relays I have tested were 
made by reputable manufacturers and were generally tested at about a 
15Hz rate.  In a well designed amp guaranteed to not hot switch driven 
with the proper coil voltage the life should be very close to the 
mechanical life.

There is a problem using a relay as a T-R  device where the receive side 
of the contact sees only very low current (gold plated or gold flashed 
contacts are best) and the transmit side sees high current (definitely 
not gold plated).  The dilemma is what type of contact material to use.  
Generally the high current side rules and the low current side may need 
a bias current to be reliable.  Often using 2 relays in parallel or 
bifurcated contacts will give the desired reliability.

73,
Larry, W0QE


On 11/9/2013 9:54 PM, Jim Brown wrote:
> On 11/9/2013 5:44 PM, MU 4CX250B wrote:
>>   I have had Jennings RJ1a relays last
>> decades in my QSK homebrew amplifiers.
>
> That would have a lot to do with the use they get. How many contest 
> QSOs do you make in a year?  I do a lot, and after the second time 
> having to replace relays in the middle of a contest, I've switched to 
> semi-breakin.  :)  I use Ten Tec Titans, which are well sequenced.
>
> 73, Jim K9YC
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