[NLRS] My Amp

[Dr. Gerald N. Johnson]

There might be a front panel switch for slow or fast RF sensing or 
SSB/FM mode which in most VHF amps doesn't change the bias, just the 
time delay on the RF sensing relay. One can add a fairly large capacitor 
to that circuit to slow the drop out of the relay, but a better solution 
for relay life is to arrange to hard key the PA before talking. My 
exciter has a PTT output for keying linears on a 6 pin mini din plug 
that may or may not have enough to key the amplifier. Keying the relay 
before applying RF gives many times the relay contact life because 
keying with RF sensing which you are doing now makes the relay close on 
full output RF which means it arcs and burns the contacts. Hard keying 
is the way to go. Some exciters have a +TX voltage available on some 
connector or the coax connector. Some PA's need a ground to be keyed, 
some need +12. A transistor and a resistor and a feed from the 12 volt 
supply can invert one to take the other drive. I haven't data on the TE 
systems amp and your exciter to be able to show more details. The TE 
manual should show part of the way to hard key because RF sensing is so 
hard on relays.

73, Jerry, K0CQ

On 9/3/2015 3:56 PM, W9RPM wrote:
>
>
> Well, as long as we are on the subject, I was testing things out for the
> weekend, and my TE Systems 432 Amp Model 4410G keys up at full power,
> but the T/R rely chatters unless I a putting a constant tone into the
> Mic. Any ideas on it. I am pretty much an appliance operator, so not
> able to fix myself I am sure.
>
> Thanks, John
>