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Tubes Asylum Questions about tubes and gear that glows. FAQ |
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Tubes Asylum Questions about tubes and gear that glows. FAQ |
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In Reply to: Dynamic Mutual Conductance Test posted by vrogers3 on September 7, 2003 at 16:08:26:
... Nope; I think you have it right on the nose. I like the B&K 747; it is one of the better testers out there. Not perfect, but darn good. The only thing I can think of is that there is a difference, or there is something strange going on. The triode sections look to have a good tolerance, but those pentode sections are all over the place. And since they are all NOS, something is amiss. Maybe the tester has a parasitic oscillation that affects the reading. I really believed in EIA/RETMA until now.
Oh; there is a really interesting website link at the bottom of this post. What it means to me is that if the oscillations are coupled back to the input grid of the tube, there goes the readings on your fancy tube tester! Some testers use a 60Hz test signal (typically the low voltage filament winding on the power transformer), whilst others use a 5kHz oscillator. I'm not sure which is 'better'. But this is all very interesting, and might support the use of tube dampers.
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- Re: Dynamic Mutual Conductance Test - Mr. Droopy-Drawers 16:52:50 09/07/03 (0)
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