Charles,
We had some correspondence about this back in January. As you may recall, my
amp had similar symptoms, though sometimes I got fault 8 or 11 instead of
fault 9. I determined that one of the expensive transmit PIN diodes was bad
and replaced it. That fixed the problem of the amp faulting in idle mode,
but when it got close to 1500W output it would fault again. The factory
advised me to check around and under L1 on the T/R board for burn spots.
When I did that, I found that the insulation under L1 had worn away and the
coil was arcing to the PCB. I had to look very closely until I saw some
small burn marks on a nearby mounting screw, and then I saw where an arc
from the coil had burned a hole in the ground plane. This was partly
obscured by the coil itself. I removed the coil and rewound it, replaced the
insulation under the coil, and the problems went away completely.
Have you checked around L1 for evidence of burn marks? I would do that ASAP
because if its arcing it will eventually destroy one or both transmit PIN
diodes. And you know how much they cost!
73, Dick WC1M
-----Original Message-----
From: Charles Harpole [mailto:k4vud@hotmail.com]
Sent: Tuesday, December 13, 2011 9:27 PM
To: amps@contesting.com
Subject: [Amps] Alpha 87a famous Fault 9
Need help..... Have Alpha 87a that goes to Fault 9 like this Amp has been
off for month. Put switches in HIGH VOLTAGE (SSB), OPERATE, and turn ON.
No RF present anywhere, and of course, no drive...all other radios are OFF.
Amp. sits for one hour and 47 minutes showing READY. Amp automatically
switches to Fault 9 and will not re-set via OPERATE/STAND BY switch. Amp has
a history of earlier automatically going to Fault 9. All PIN diodes have
been changed 6 mos ago. Ideas? 73,
Charles Harpole
k4vud@hotmail.com
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