>
>I don' want to enter deep, but I've seen a number of 8877 working along
>their life with much bigger grid currents than 50/60ma (2-3 times more).
>Those tubes were only replaced after the scheduled "on" hours passed,
>and then discarded. Most of them later "arrived" as a gift into amateurs
>PAs, and they (the tubes...) are still doing the job.
>Years ago (10), while developing an HF amplifier using a pair of 8877 in
>Gg, a number of "accidents" occurred and the grid current peaked, for
>some while but a number of times, over the spec. max ratings.
>Those tubes not only survived but they are still alive and in good health.
Boiling gold off of the 8877's grid with HF grid current would be quite
difficult. For one thing, the temperature requirement is extraordinary.
>On the contrary, a number of brand new 8877 had failed repeatitively in
>the mid 90s' but grid current had totally nothing to do such problems.
>
>From what did they fail? Were the tubes that failed tested with a
high-potential tester?
- Ciao, Mauri
- Rich..., 805.386.3734, www.vcnet.com/measures.
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