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Old 21st Sep 2022, 11:03 am   #12
Valvepower
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Location: Rayleigh near Southend-On-Sea, Essex, UK.
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Default Re: Quad 22 KT66 to 6L6 with Cathode resistor increase?

Quote:
Originally Posted by PJL View Post
The early coke bottle KT66 (VT75) have a similar anode structure to the 6L6G but, as others suggest, the 6L6GC characteristics are likely to be different so you need to check the cathode current and adjust the auto-bias to set to the same as the KT66.
Many thanks for all the replies.

Taking measurements with both 6L6GC and KT66 and adjusting, if necessary, is a sensible route.

There are well documented performance figures for the Quad 22, so I can check a unit with 6L6GC against these as well.

The various variants of the 6L6(GC-WGB...etc.), 5881 and 7581A are a bit of a can of worms.

Regards
Terry.
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