With MOSFETS or bipolar transistors, push-pull is easy to get using either
push-pull conventional transformers or balanced transmission line
transformers. It is easier because of the much lower impedance levels that
transistors operate at. The push-pull amplifier has much better reduction of
second harmonic output, which makes the low pass filters simpler. Tuned
tank circuits are hardly ever used with transistors beyond the QRP level.

Bill W0IYH


"Henry Kolesnik" wrote in message
m...
I just noticed in this ad: http://hamstation.com/ybstkftmk5.htm that
Yaesu's FT-1000 finals are MOSETS in push-pull. I don't ever recall
seeing a pair of final tubes in an xcvr or linear in push-pull except
perhaps way back in a very old QST. Can someone explain why push-pull is
used in the Yaesu and why we don't see it in "modern" tube amps?
tnx

--

73
Hank WD5JFR