[Amps] Plate modulation from power supply ripple?

[TexasRF at aol.com]

Hi All, even if the plate current did not change, wouldn't the changing  
plate voltage result in changing power input and corresponding changes in 
power  output?
 
That sounds like modulation as well.
 
Taking this to an extreme, removing the filter C altogether, any hum  
modulation then? How much?
 
73,
Gerald K5GW
 
 
 
 
 
 
In a message dated 10/3/2013 8:35:17 A.M. Pacific Daylight Time,  
ww1c at outlook.com writes:

Hi Gary,  All
I was thinking about your statement and looking a typical tube anode  
characteristics (curves).If I read this correctly, change in plate voltage  does 
cause a change in plate current.Is this not plate modulation?  I am  not 
sure if the operating class changes this.Perhaps I need to simulate this  too...
Thanks
MarkkuWW1C

> From:  garyschafer at comcast.net
> To: ww1c at outlook.com;  amps at contesting.com
> Subject: RE: [Amps] Plate modulation from power  supply ripple?
> Date: Wed, 2 Oct 2013 12:36:06 -0500
> 
>  You don't hear the ripple because it does not modulate the linear  
amplifier.
> If you were to run the amplifier in a non-linear mode such  as class C 
then
> it would plate modulate it.
> 
>  73
> Gary  K4FMX
> 
> > -----Original  Message-----
> > From: Amps [mailto:amps-bounces at contesting.com] On  Behalf Of Markku
> > Oksanen
> > Sent: Wednesday, October  02, 2013 12:40 AM
> > To: amps at contesting.com
> > Subject:  [Amps] Plate modulation from power supply ripple?
> > 
> >  
> > All
> > I was simulating (with LTspice) a three phase  power supply where the
> > secondary is in star configuration with  full wave rectification. You 
can
> > get also a second voltage from  this by connecting to the center of the
> > star, this voltage is  half of the full wave rectified voltage and is
> > only half wave  rectified (per phase), 3 pulse in stead of 6 pulse for
> > the higher  voltage.
> > It turns out that even relatively high value (tens of  uF) filter
> > capacitors would leave some 10% of ripple on the lower  voltage.  Now 
the
> > question is: How much plate modulation  this make?  The ripple frequency
> > is 150 Hz and to me this  looks like your regular high level, plate
> > modulated AM  transmitter.  Why do we not hear this on a typical signal
> > if  it is there?
> > 
> > MarkkuWW1C
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> > Amps at contesting.com
> >  http://lists.contesting.com/mailman/listinfo/amps
> 

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