[AMRadio] TH vs TL

Barrie Smith barrie at centric.net
Sat Feb 23 13:41:02 EST 2008

I'm curious as to the difference in RF performance between the TH (as in 250TH) and the TL (as in 250TL)  versions of older triode tubes.

Looking through the Eimac spec sheets for various old, glass triodes, the only real difference appears to be that the TL versions require higher grid bias in class C RF service.

I've used the TH versions of several of the older tubes a good number of times over a many year period, but I've only used the TL types in modulator service.  However, if there is no real difference in RF performance between the two in class C, I'm tempted to.

73, Barrie, W7ALW

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