[JMS] 250 Watt modulator for 90881

[C E]

Hi Jim:
That thought crossed my mind but using a variant of
the approach. How about using a 6.3 VAC filament xfmr?
I think the voltage will be low enough to safely
determine the transformed voltage at the other side.

Whadda think? Cal. 

--- JAMES HANLON <knjhanlon at msn.com> wrote:

> Cal,
> 
> You could figure out the primary-to secondary turns
> ratio of your modulation transformer with a simple
> measurement.  Drive one side with an audio
> oscillator or other audio signal, say the output
> from your receiver, and measure the voltage on both
> sides of the transformer.  The turns ratio is just
> the ratio of the two voltages.  The impedance ratio
> from one side of the transformer to the other is the
> square of that turns ratio.  You can look up in the
> ARRL handbook the impedance for a pair of 811's in
> Class B, and knowing the impedance ratio from your
> measurement and calculation you can determine what
> the design impedance for the other side of the
> transformer is.
> 
> Does that make sense?
> 
> Jim, W8KGI
>
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