I can not do a freq response test because I do not have a proper sig
gen. Mine is a cheap step job and the amplitude is all over the place.
I put a 1khz sine wave into an earphone sitting on the mic and measured
p-p values with a scope....
Pin 2 V7A (grid)........ 5mv
Pin 7 V7b (plate)........50 mv
Pin 2 V8 grid............. 3 v
Pin 1 V8 plate.......... 40 v
Pin 5 V9/10 grid........ 20 v
Pin 3 V9/10 plate....... 10 v (standby)
Pin 3 """"""""""....... 50 v
I assume that where the voltages dropped it had something to do with the
transformer being across the output and the standby more for the mods.
I all cases, the amplitude dropped a bit and the sine wave got a little
"bent" when going from stdby to phone. It flattened out slightly.
In the case of the grids of the mods.. a great deal of distortion was
seen when in the phone mode. Only an approximation of a sine wave with
jagged festoons all over. None of this was seen when looking at the
plates in the phone mode.
So, what can we make of this?
js
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