>
>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.
Was one side of the heater not hard-wired to the cathode when the heater
blew?
Was either side of the heater grounded?
>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
>
Looks good to me. Sputtered gold typically produces large differences in
positive and negative leakage currents.
>
cheers, Steve
- Rich..., 805.386.3734, www.vcnet.com/measures.
end
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