[TenTec] Failure Modes for 811a tubes?
wa9jml at frontier.com
Thu Oct 17 19:47:25 EDT 2013
I bought a nice Centaur amplifier from a list member a few years ago,
and finally got around to putting it on the air. I took out the 572B
tubes that were installed in the amp, and put the original 811A tubes in
there so that I would be less likely to blow up by 600 watt autotuner. I
have since bought a new 238C tuner from Ten Tec.
It was working fine, until the net last Sunday. Suddenly, the output
power dropped. I noticed later that the heater in the center tube was
out. I cycled the power switch, and it came back on for a while, then
went dark again. I have two sets of 572B tubes for the amp, but I am
curious about this being a common problem with 811A tubes.
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