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Vacuum tubes: Difference between revisions
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'''Vacuum tubes''' aka ''electron tubes'' or ''(thermionic) valves'' were the workhorse active components in electronics up to the mid-1960s. | '''Vacuum tubes''' aka ''electron tubes'' or ''(thermionic) valves'' were the workhorse active components in electronics up to the mid-1960s. | ||
==Tube selection== | |||
The mechanical tolerances in vacuum tube manufacturing lead to a slight variation in many tube parameters, e.g. the I/V curves, and the dynamic behavior. Further, tubes exhibit a slight change in performance in the first hours of operation. While those variations are acceptable in many applications, Tektronix chose to age most of their used tubes to avoid the alteration of performance in the first hours of operation of new equipment, or spare tubes. In many applications, the same tube was further selected after aging for parameters as low grid current or matched in pairs for a particular bias condition. (In contrast to popular belief in the audiophile world, a "matched pair" of tubes is meaningless, unless the exact bias condition in operation is known and tubes are matched in that condition.) This is the reason why there are often 5 or six different part numbers for the same tube, since they were differently selected. | |||
* [[Media:157- checked and tested tubes specs and procedure.pdf|157- Checked and Tested Tubes: Specs and Procedure (PDF)]] | |||
* [[Media:Tek_tube_aging.pdf|Tube Aging (OCR, PDF)]] | |||
<!-- * [[Media:Tek raw tube and aging specs.pdf|Raw Tube Aging (PDF)]] --> | |||
==Tube failure== | ==Tube failure== | ||
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==Links== | ==Links== | ||
* [[wikipedia:Vacuum tube|Vacuum tube]] @ Wikipedia | * [[wikipedia:Vacuum tube|Vacuum tube]] @ Wikipedia | ||
* [[Media:Tube basing index.pdf|Tube Basing Index (PDF, needs OCR)]] | |||
[[Category:Circuits and Concepts]] | [[Category:Circuits and Concepts]] | ||
[[Category:Repair issues]] | [[Category:Repair issues]] | ||