[AMRadio] RE: Using a Ranger as a driver

Gary Schafer garyschafer at comcast.net
Wed Feb 13 13:34:58 EST 2008

Yes Jeff, the peak voltage supplied by the modulator must be equal to the
final plate voltage. The modulator voltage adds to the plate voltage to make
the voltage double during positive modulation peaks. On negative modulation
peaks the modulation voltage subtracts from the plate voltage making it go
to zero.
The peak to peak modulation voltage will be 2x plate voltage.

Gary  K4FMX 

> -----Original Message-----
> From: amradio-bounces at mailman.qth.net [mailto:amradio-
> bounces at mailman.qth.net] On Behalf Of Geoff/W5OMR
> Sent: Wednesday, February 13, 2008 12:35 PM
> To: Discussion of AM Radio in the Amateur Service
> Subject: Re: [AMRadio] RE: Using a Ranger as a driver
> Gary Schafer wrote:
> > While it is true that for 100% modulation the modulation voltage must be
> > equal to the final plate voltage.
> No.  Not equal to, but *twice* as much.  2*Ep
> > But it is also misleading to say that it is strictly a function of
> modulation voltage.
> >
> What other voltage is present at the plate (other than the DC supply
> voltage) if not for the AC voltage achieved by the modulator?
> High-level plate-modulation, we're talking about.
> > The modulation transformer secondary works into a certain load impedance
> > (resistance) supplied by the final plate circuit of the RF stage. While
> it
> > is true that the modulation voltage must match the final plate voltage
> (for
> > 100% modulation),
> 2*Ep.
> --
> Driving your AM Rig without a scope,
> is like driving your car at night, without headlights. (K4KYV)
> --
> 73 = Best Regards,
> -Geoff/W5OMR
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