Arlen says:
>Yes, in a parallel circuit, Q is maximum when R=0. Here are the
>equations:
>In a parallel circuit, Q = X/R. X, of course, is frequency dependent,
>and if R is made of a highly conductive material (nichrome, copper,
>silver, etc) then R is also frequency-dependent, predictable by the skin
>effect equations. But the frequency dependence of X will dominate.
>In a series circuit Q = R/X
NO NO NO NO!!!!!!!!!!!!!!!!!!!!!!
In a series circuit, Q = X/R, while in parallel, Q = R/X. If you shunt an
inductor witha low resistance, you kill the Q. If you wind an inductor with
resistance wire (i.e. high series resistance), you kill the Q.
So in the parallel case, as f goes down, X goes down, and for a given R, Q
goes up.
As various people have said, it's the damping of the whole circuit from
plate through suppressor, DC blocker and tuning C that's important in
suppressing the parasitic.
73
Peter G3RZP
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