|[AMRadio] Home brew AM Cathode modualtion|
k4kyv at hotmail.com
Sun Oct 3 13:45:01 EDT 2004
>The 450th is a big triode, so I dont think you can run it single ended pie
>net output, you would need to do 2 250th tubes in push pull or something,
>but the 450th would do the cathode modulator quite well.
You could use a single-ended pi-network type output circuit, with a balanced
grid tank coil. That is knows as "Rice" neutralisation. You don't get as
perfect null as you can with a balanced plate tank cincuit or a pushpull
arrangement, but it works well enough that it became the standard design of
tube type broadcast transmitters starting in the late 50's.
I used that circuit with the first high power rf final I ever built, using a
304-TL in the final, because I didn't have a large split stator tuning
capacitor on hand.
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