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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: Re: Help this pathetic newbie to tubes : ) posted by Jim McShane on August 7, 2006 at 07:22:40:
For years when I tested tubes, I also tested emissions at various lower than manufactured specified filament voltages. Interesting info comes forth, but does not indicate a clear picture until 100s of various tubes have been tested & seems to follow cettain years of manufacture. Obviously changes in the filament oxide coating formula & slightly different targeted (design center) operating temperatures of that oxide at 6.3 volts effects reduced voltage results.Most NOS 6.3 volt preamp tubes still have passing emissions at 4.2 volts & some power tubes pass emissions at as low as 3 volts. A mostly used up preamp tube that tests quite good at 6.3 volts most likely will fail emissions at 5.0 volts. Various manufactures brings different results to some degree & all bets are off regarding non-oxide filament tubes. I have never received a clear picture with 2A3, 6B4G and the like. Some of these tubes in NOS boxes fail at 4.2 volts instead of 6.3 volts, others pass.
All this data I collected will only reference my tube tester with any accuracy. I am just nuts enough to compile all this info.
No doubt, like Mechans, I prefer NOS and expect NOS when I pay a premium for NOS. It is a let down when a used tube was received in-place of NOS. A major culprit of used tubes in original boxes that match the box manufacture name were TV repair persons. They usually did not throw out good used tubes.
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Follow Ups
- NOS Indication........kind of - Jimmy 10:48:57 08/07/06 (0)
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