'Vacuum Tube Valley' is such a good resource for tube-related info that I'm surprised more people don't read it. http://www.vacuumtube.com/
Issue #19 contains LOTS of info on 6550s/KT88s/KT90s. With new tubes costing $40 - $80/pr. and NOS tubes going for far more, #19's $22 purchase price is well worth it IMO.
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Issue #19 contains LOTS of info on 6550s/KT88s/KT90s. With new tubes costing $40 - $80/pr. and NOS tubes going for far more, #19's $22 purchase price is well worth it IMO.
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