Actually there seems to some "confusion" about the change caused by
nichrome. I don't intend to argue this, so this will be my single
group post on this subject. People should use common sense and
think about this stuff *very* carefully.
Wes Stewart's conclusion was there is no real difference at all in
VHF performance no matter what type of material is used in the
inductor, that even a very small change in resistance or turns could
easily produce identical results at VHF. There was no "magic", the
suppressors were essentially the same, or could easily be made to
appear the same.
Give the following the common sense test.
1.) The Rp (the parallel impedance) of direct connection is zero
ohms when the connection is short, direct, and lossless.
2.) Rich states over and over again LOW Rp values are best for
stability, and uses that justification now (before it was "low Q",
now it's low Rp) as the reason his product "works".
3.) If the lowest Rp comes from a direct short, and the best
stability comes from lowest Rp, a direct short across your
amplifier's suppressor should produce the most stability.
Traditionally, people have always added series loss resistance
to stabilize a PA. The loss resistance can be something as simple
as a single conventional resistor (in an audio amplifier, or in the
screen or grid path of an audio or RF amplifier), or a parallel L/R
circuit (the conventional suppressor we are all accustomed to
seeing).
In all cases, the lowest high frequency gain and most stability
occurs with a HIGH value of series resistance (more turns on the
coil- so the resistance dominates, or if it is a lumped resistance a
larger resistance value).
Ask yourself this. After years of knowing more turns (higher
Rp) means more stability (if our PA's are unstable, we generally ADD
turns to the suppressor - increasing Rp), or knowing that a resistor
in series with the anode in an audio amplifier makes the PA more
stable than a direct connection to the rest of the circuit, or
knowing that HIGHER anode load resistance in a Hi-Fi amplifier hurts
high frequency response (amplification).......
why is lower Rp suddenly a better method of reducing VHF gain,
contrary to what we all experience in actual circuits???
73, Tom W8JI
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