[Amps] Historical question-probably OT

[Peter Chadwick]

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)