At Dayton, I got a 1960 ARRL Handbook ( got to update the station!) for my
collection. It has an interesting HF amplifier in it, using a pair of 4X250,
(NOT 4CX) running, it is claimed AB2 passive grid, although the drive level
discussed seems to me too low for AB2. It is enough for AB1, though. Some
other interesting historical features are the power supply, which used
germanium rectifiers. A transformer with two 325 volt windings, each voltage
doubled and wired in series, and no bias regulation, which again makes me query
the AB2. Also, a fixed link coupled output network, pretty well necessitating a
tuner - shades of today's solid state stuff!
Another point of interest is the modification of the tube sockets to reduce the
back pressure so that a big axial fan can be used for tuning. The design was
published in a 1958 QST. Has anyone here ever heard of any of the 250 series
being run for linear amp service in AB2? I've only ever seen AB1 discussed.
73
Peter G3RZP/W6 (this week)
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|