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@contesting.com] On Behalf Of Markku
> Oksanen
> Sent: Wednesday, October 02, 2013 12:40 AM
> To: amps@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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