>If it passes those tests AND as long as the suppressors are OK, I can in
>NO WAY accept that a parasitic will occur during use. Arcs on standby are
>gas or barnacles in the tubes....note that those arcs rarely if ever are
>associated with capacitor or switch failure but can blow grid chokes and
>tubes.
I've read Rich's information on his webpage and I think I can repeat his
theory:
He says that whenever you have a change in anode current in a tube that a
small, damped VHF signal will result. He says you can observe this with
an O-scope or a spectrum analyzer. If there is enough Q in the VHF tank
circuit in the PA, then an osicallatory condition could occur.
While I agree that the whole tank circuit in a tube IS VHF resonant, I am
not sure of how a transient current condition in the tube can produce a
VHF ringing. I would like to know if anyone has seen this on a piece of
test equipment. If true, it does add a lot of credence to Rich's
theories.
ALL tubes contain parasitics. There is a BIG difference between a
parasitic and a parasitic oscillation. It's easy to get them confused.
A parasite in a tube is the lead inductance and stray capacitances, etc.
that exist in the real world. Even a leaded capacitor has parasitics
(lead inductance).
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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