Thread: Testing 807's.
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Old 14th Jul 2018, 7:43 am   #12
Diabolical Artificer
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Location: Sleaford, Lincs. UK.
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Default Re: Testing 807's.

The anode cap does have a ferrite in it, but I will stick the runaway valve in an amp and check for oscillation. My tester does have anti oscillation measures - ferrites on all valve base pins etc.

That's some amp Howard, did you do a write up and any chance of a look at the schematic? Looks an interesting amplifier. Finding reasonably matched valves is tricky. I matched two quad's, just about, on my homemade tester only on quiescent current, I haven't enough 807's to match to any tighter standard.

Regarding trying to match valves for a PP parallel OP stage, I did wonder about running the OP stage in a mixture of fixed and cathode bias to try and iron out any mismatch.

Andy.
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