[Amps] vacuum relay problem

[N1BUG]

Hi again Felipe,

If it lasted that long the first time, it probably is not a hot 
switching issue... I guess. :)

The way I check for that is with a dual channel scope. One channel 
looks at RF from the transceiver during keying or voice/VOX 
operation. Transceiver should be feeding to a dummy load, NOT 
through the amp. The other channel looks at a small DC voltage fed 
through the amp relay N.O. contacts. You want to see that the relay 
contacts are completely closed and stopped any bouncing before the 
start of any RF output from the transceiver.

In my particular case, the amp relay(s) are completely closed and 
stable in 2 milliseconds after key closure or PTT/VOX activation (I 
used some speed up circuit on them), RF begins at 7 milliseconds 
after key closure or PTT/VOX operation. Be sure to check in the 
other direction too... going back to receive. I forgot the numbers I 
measured, but I know RF stops some milliseconds before the relay 
begins to transition back to the receive position.

73,
Paul



Felipe Ceglia wrote:
> Hi Paul,
> 
> I am not sure it is not being hot switched. How could I check for that?
> 
> The amp is an harris RF110, and it is using the original keyline /
> 26v, and activated by an FT1000 (old model). This setup has worked
> without any problem for more than one year on a bunch  of contests.
> The jennings relay took a lot of time to get bad, the kilovac took
> only a few hours :(