[Amps] Ten-Tec Centurion

[Georgens, Tom]

I have a Centurion at my contest station in Barbados that works flawlessly
on 10-80 but will arc on 160.  It is tuned into a resonant antenna with a
reasonable SWR.

On 160, the amp will occasionally arc immediately on key down.  If it does
not arc immediately, it will not arc if the key is held down.  Also, when it
does not arc, it tunes smoothly and at the predicted settings.  All of the
arcing is in the Tune cap and is not always in the same place.

My theory is that there may be power overshoot from the TS850 on the leading
edge of the carrier that is causing the arcing.  It is hard to see this on
the wattmeter and my 3 other amps all work fine.  Does this seem like a
reasonable theory and is there any way to compensate for this?

On my most recent trip, I performed a flawed experiment.  For convenience, I
used a different TS850 to drive the amp and the problem occurred only once
out of dozens of tries.  I then moved it to the TS850 where I had previously
noted the problem.  In this case, I was never able to reproduce the problem.
I tried mistuning to some degree but no hint of the problem.  However, when
taking the whole thing apart, I noticed that I had never connected the amp
relay cable.  The amp was using RF sensing to key the relay.

As I said my experiment was flawed but I would like to understand what is
really happening.

Any suggestions would be greatly appreciated.

73, Tom W2SC 8P1A

Tom