The Apache does use a driver transformer. A triode connected 12BY7 is transformer coupled to the grids of the EL34's.

For AB1 operation, look at any of the hi-fi type tubes (EL34, KT88, 6550, 8417, etc). Most will deliver plenty of power without grid current. Another good choice is the 6146. 807's don't do very well in AB1. They just can't deliver the power of many other tubes.

73,
Darrell, WA5VGO


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