[AMPS] Filament supply?

[Eric Lowell]

Gents,

This is probably a really dumb question, but I have searched my handbooks,
the web etc and can't find an answer.

I have worked primarily with transistors in the past, so it freaks me out a
little to see ripple anywhere in an amplifier.

Now, looking at various tube amplifiers, I notice that almost all use an
unrectified AC for the filament, even those where the cathode is directly
heated.

Why is there no AC hum on the transmitted signal?

Is there a reason, other than simplicity, for using AC for the filament?

Thanks for the bandwidth.

Regards, Eric W1EL



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