Hello Dick et al,
Thanks for your most interesting and informative explanation re the 8877
debacle etc. You asked for some further "inside information" and I will
share a tiny bit.
In the late "80s, I attended an RF Expo show in Anaheim at the height of
the 8877 failures. Naturally, I went into the Eimac booth and met a W7
engineer from their Salt Lake plant. I asked what he could tell me about
the problem as I had always wanted to use the tube but avoided it because
of the high failure rate that was being reported. He willingly told me
about a number of problems that they had that resulted from the
production transfer from San Carlos to Salt Lake. Even without
intentional changes, the transfer of technology is always a high risk
operation as subtle, small unintentional ones can be a catastrophe as you
may have been suggesting about the oxide coating.
In particular, however, he mentioned the fact that they had substituted
some other non-noble metal for *platinum* that I presumed was a cost
reduction effort. Then he went on to tell me that the temperature
coefficient of the substitution was a large part of the failure mechanism
and I don't recall its location. I didn't hear anything about a "cathode
dam" and possibly that may have been one in the same of what you
described. So, for what it is worth........this is a little bit more on
the subject!
73,
Marv, W6FR
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