[AMRadio] AM power

[Geoff Edmonson]

On 06/18/2011 09:55 PM, Gary Schafer wrote:
> Jeff,

My name is Geoff.  With a G e o f f.

> An easy way to prove this to yourself: set your scope on the output of your
> transmitter for say 2 divisions of carrier.

Seems I'm the one that told you I -did- this.  That's why I KNOW I've 
got a voice with an SR of 4, when there's proper voltage on the modulators.
250TH's, in Class B,  like ~3000VDC.  I run about half that and 0 bias.  
At that level, there's 220mA of resting current.  There's not enough 
voltage to properly modulate the final - the positive peaks are kinda 
rounded off, they don't reach, but with an SR down to 3 (instead of 4) I 
can run the carrier up to around 200w.


> Then modulate it with a single
> tone until the voltage on the scope doubles (4 divisions). That is 100%
> modulation I am sure that you would agree.
>
> Now remove the single tone and modulate with your voice until the voice
> peaks hit the same 4 divisions on the scope. You are now modulating 100%

what you're not getting, Gary, with the proper voltage and everything 
running the way it should on my rig, when I DO hit the same point on 
positive voice peaks as the single-tone, the negative peaks aren't 
anywhere -near- the baseline of the carrier.  That is -not- 100% modulation.