Will,
Applying signal and oscillator to g1 is, as you say, an old technique. It
had problems when the oscillator is a long way from the signal frequency,
in that the input tuned circuit attenuates the oscillator: it's also more
susceptible to pulling, which is why it wasn't too popular a technique in
the 'good ole days'. However, it got used a lot in VHF converters. Its
well written up in 'techniques of radio design' by Zepler - a guy who had
the dubious distinction of having designed radios used by both sides in
WW2! - and in Sturley's 'Radio Receiver Design'.
The pulling problem led to the developemnt of the pentagrid and triode
hexode mixers, complete with their various problems. The use of 6AS6 would
be interesting, since it has a high mu g3, allowing separation of signal
and oscillator. the much vaunted 7360, according to the manufacturers data
sheet, is actually capable of performance little or no better than a
12AU7!
Vy 73
Peter G3RZP
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