on 1/14/02 5:45 AM, Tom Rauch at w8ji@akorn.net wrote:
> A matching system in a GG class B or AB amplifier serves three
> important functions:
>
> 1.) It matches impedances
>
> 2.) It provides a low impedance path to the chassis for tube
> cathode harmonics
>
> 3.) It prevents cathode harmonics from reaching the exciter and
> causing problems
>
> You can't do that with a broadband transformer. It requires a low
> pass network with a low-reactance capacitor (compared to the
> tube's driving impedance) shunting the tube cathode to ground.
Tom,
Correct me if I am wrong, but doesn't the literature lists one more reason
for having an LC based matching network in you amp? It tends to act as an
energy storage medium for when the tube is in cutoff - the old flywheel
analogy. A transformer wouldn't do the same thing. Or do I have it wrong
in that this "flywheel" analogy only applies to the tank circuit on the
output of the PA...........
73,
Jon
NA9D
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