I have an Al-82 amp that is blowing the zener diodes in the bias
circuit. The first time it happened, ZD1 blew first then a few weeks
later, ZD2 blew. I replaced both at the same time and asked the guys at
Ameritron what would cause them to blow. They told me it is usually caused
by a tube arcing over. After I replaced the diodes the amp worked fine and
put out full power. Two days later, I noticed the tubes getting hotter
than usual again and checked the idle current and it was high. ZD2 blew
again. Has anyone seen this and/or have any ideas? I have heard no
crackling or snapping and I really baby the amp. I run it SSB only at
about 500W on 75M and 1000W on 160M. SWR is low on both bands <1.5:1.
Thanks,
Joe N1FCJ
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