[AMRadio] Ranger Audio XFMRs

John E. Coleman (ARS WA5BXO) wa5bxo2006 at pctechref.com
Fri Nov 17 15:16:31 EST 2006

I thought I read where Jack said the scope pattern at the grids of the
modulator tubes looked altogether different than the pattern at the plate of
the driver tube.  If this is true then the driver XFMR might be shorted.  I
am not real familiar with the driver XFMR on the ranger but if it is one of
those common 1:3 (single class A Plate to Push Pull AB1 grids) they saturate
real easily with a too much plate current from the driver tube.  This can be
caused by a gassy driver tube or wrong bias, which is generally cathode type
bias, or leaky grid coupler capacitor from the previous stage.  I'm also
pretty sure that Jack checked the voltage all around the driver tube so the
mystery is looking like the butler sabotaged one of the XFMRS either driver
or modulator.  If it ends up being the driver XFMR, I have one of those 1:3
XFMRs here. NOS 

Stancor part number A-53C  
10K primary 90K secondary.
10 ma primary current 

John, WA5BXO

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