The technical wizards out there will probably hammer me, but
it sounds as though a number of things could be going on. You
did not mention what rig you are using, and what you mean by
50 watts. BTW, my 91B usually runs with about 35w input
on CW.
It is possible that your exciter's internal ALC is not functioning,
allowing certain syllables to ramp and exceed the desired input
level. This can be a particular problem with some rigs when the
output is lowered to drive an amp, as with lower drive in the
exciter, alc may never be operating.
It also sounds like the loading on the amp might be a little light.
Try loading a little heavier and see if that calms things down a bit.
It's usually detection of grid current peaks that trip the overloads.
There is also the possibility that something in your antenna system
is breaking down on RF peaks.
This is the order in which I woukd attack the problem. If it is the
first one (depending on your rig type) you might have to run it at
rated power and swamp the input to the 91B.
Good Luck and 73
Dallas W3PP
----- Original Message -----
From: KN5H <kn5h@earthlink.net>
To: <cq-contest@contesting.com>
Sent: Wednesday, March 13, 2002 2:18 PM
Subject: [CQ-Contest] Alpha 91 protection ckt question
> All:
>
> Who can assist me with this?
>
> Only on 10 mtrs, a few certain key sounds, "five" and "nine", specifically
the "I", kicks the amp offline.
>
> The SWR is not an issue. Overdriving is not an issue. The transceiver
output is barely 50 w.
>
> No compression seems to help. A hand mic was substituted for the boom
headset mic but the trouble continues.
>
> Any hints?
>
> 73 de KN5H
>
>
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