I like the idea of modeling the circuit. However,
much of the circuit is not considered. People often don't realize that
that there are additional inductances due to the current paths thru the
chassis and often these impedances are in both the input and
output circuits. I have seen many amplifiers that have very long paths
from the
anode (PLATE) thru the coupling capacitor, PI input capacitor, to chassis and
back to the grid and cathode circuit. Sometimes this path is a foot in
length or
more
. This single loop amounts to nearly a uH of inductance with
who knows what other impedances tied to it and signals sharing the
path.
My electronics instructor used to say often the problems with a circuit
is the component you can't see. Especially with RF circuits.
73
Bill wa4lav
William L. Fuqua III , P.E. EE
Department of Physics and Astronomy
CP 177 Chemistry Physics Building
University of KY
Lexington, KY 40506-0055
Phone 859 257-4155
--
FAQ on WWW: http://www.contesting.com/FAQ/amps
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
|