I'd be interested in comments on the following results. The polarities given
are correct. All tests are between anode and control grid.
I bought a pair of 8877, I'm fairly certain they are industrial machine
pulls. One blew its heater the first time I powered it up. The other works
fine in a 6m PA.
Blown one (8722 date) anode+, grid- 10uA at 10kV. Anode -, grid+ 10uA at
5kV.
Good one (8705 date) anode+ 10uA at 13kV, anode- 10uA at 8kV.
For comparison:
New 3CX800, never had power on it. 0uA at 10kV, both ways round.
New 4CX800, never had power on it, anode+ 5uA at 10kV, anode- 5uA at 8kV
Used but fully working GU74(4CX800), anode+ 5uA at 10kV, anode- 5uA at 6kV
Thanks,
Steve
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