[AMRadio] RE: the weekly receiver update

[W7QHO at aol.com]

In a message dated 4/19/02 4:55:34 PM, k4kyv at hotmail.com writes:

>I  recall from studying the tube manuals that the 28 volt tubes in the
>R-392 
>are identical to standard tubes except for  the filament voltage.  The
>tubes 
>perform well at 28 volts on the plate due to  circut component values,
> but 
>standard 6 and 12 volt filament tubes would work identically.  Never 
>actually experimented to see if there was any difference.

Don is correct with the exception of the 26A7 audio output tube which was 
apparently designed for the low plate voltage.  As a consequence of the low 
plate voltage, though, the rest of the tubes are operating way out on the 
ends of their characteristic curves and the gain of the RF and IF amplifiers 
are low requiring extra stages.

Dennis D.  W7QHO
Glendale, CA