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Old 06-15-2005, 08:26 PM
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wa2ise wa2ise is offline
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Join Date: Dec 2002
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Quote:
Originally Posted by joe_tbird
I've heard of tubes failing that way--it's called "sleeping sickness" according to one technical book I read on the subject.
Have heard that you only need to draw a few microamps of current from an otherwise heated but unused tube to keep it from getting sleeping sickness. In an AM/Fm radio, I've connected a 470K resistor between the AM B+ and the FM B+ (at the switch is a convenient point) to draw small amounts of current from the unused tubes. This wouldn't be enough current for local oscillators to run so no am<->FM interference should occur.
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