Heathkit SB-221 HF Amplifier: Difference between revisions
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Created page with "3-500Z tubes have been notorious for short shelf (storage) life since Eimac first started making them. Almost everybody who's designed and manufactured amplifiers and used tho..." |
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Revision as of 20:12, 31 August 2017
3-500Z tubes have been notorious for short shelf (storage) life since Eimac first started making them. Almost everybody who's designed and manufactured amplifiers and used thousands of these tubes recommends: Don't keep spares on hand unless you rotate them through a working amplifier, and get them "very hot" (anodes red/orange) about every six months. Otherwise spares often go bad on the shelf, becoming gassy beyond the possibility of repair by the gettering process, which only occurs when the anode gets very hot (filaments won't help).