[AMRadio] Driver Xfmr

[W7QHO at aol.com]

In a message dated 2/6/03 7:25:39 PM, garyschafer at attbi.com writes:


> Just put a resistor in the plate of the 
> audio driver tube, in place of the transformer primary. I think around 
> 10k 2 watt will work ok. Then couple the plate of the driver to the grid 
> of one of the 1625s with a capacitor. Leave the secondary of the driver 
> transformer hooked to both grids and bias as it was.
> It will work as an auto transformer to couple audio into both tubes. 
> Works fine! Although gain will be somewhat less than with the transformer.
> 

I've done this too with FB results as long as one is not trying to push any 
power into the next stage, but only providing a voltage swing.   Never had a 
DX-100 so have to ask, in just what class are the 1625 modulator tubes 
operating i.e., AB1 or AB2?   If AB1 the scheme under discussion (or a phase 
inverter, or an itty-bitty transformer) should work FB.   Nada if AB2.

Dennis D.   W7QHO
Glendale, CA



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