[Collins] 75S-3 Tubes

[Dr. Gerald N. Johnson, electrical engineer]

6EA8 and 6U8A/6KD8 are pin compatible. Checking my RCA tube manual, the
Gm of the EA8 is a little greater (15 to 20%) which makes it have a
little less noise and a little more gain. I'm sure many modern tube
interchange lists would consider them equal. Later S-lines used 6EA8 in
the stages where 6U8A were in earlier S-lines. I don't know if any
circuit components were changed in the redesign process. I presume that
they found better results with the 6EA8 or else they found a train car
load of 6EA8 cheaper than 6U8A...

73, Jerry, K0CQ

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