Tom says;
>That looks like a well thought-out system compared to say...a
>resistor in the cathode that would always have the proper phase
>and an almost constant value of feedback.
I obviously didn't make myself clear. I was musing along the lines of 'it was
done in the 30L1 for another reason that is not immediately apparent', rather
than 'this is an approach designed to give negative feedback'.
Another thought that comes to mind is that the capacitors were supposed to be
2200pF, and a 0 got missed off. or the drawer was marked 2200pF, the caps were
220pF, the device worked so 220pf went on the drawing..... Don't laugh, these
things happen - like the 747-400 that Boeing fitted with a 25 Amp circuit
breaker where it was supposed to be 2.5Amps........
The (simplified) circuit for the 30L1 that I have shows the plate choke as
44millihenries, which I find hard to believe.
One problem with analysing RF amplifiers with NFB is that the circuit diagram
doesn't always tell you the full truth. This particular case seems rather dodgy,
to say the least, but was there another factor involved that we know not of?
We'll probably never know...........
73
Peter G3RZP
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