[AMPS] parasitics

[Jon Ogden]

>>While I agree that the whole tank circuit in a tube IS VHF resonant, 
>
>I do not.  The HF tank circuit is  a lowpass filter.  The VHF resonance 
>at hand involves the anode-grid C, the total inductance of the conductors 
>between the anode connection and the Tune C, and the capacitance of Tune 
>C.  Typical resonance frequencies are from roughly 65MHz for largish 
>tubes like the 8171, to roughly 170MHz for small ceramic tubes like the 
>3cx800A7.  .  The VHF resonance picture is further complicated by VHF 
>self-resonances within the Tune C.  .  .  Murphy was seemingly right.  
>Things are usually more complicated than they look.

I stand corrected.  I think I meant the VHF tank circuit created by the 
stray capacitances and inductances in the tube, anode and tune C 
circuits.  Yes, the output PI-network IS a lowpass filter.

73,

Jon
KE9NA


--------------------------------------------------------------------------
Jon Ogden

jono@webspun.com
www.qsl.net/ke9na

"A life lived in fear is a life half lived."




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