The AM Forum

  Among the items I came home with from Moxboro this past Saturday was a zip-lock bag of axial-lead inductors wound on resistor cores. The resistors, based on the visible color bands, are 22 ohm, and their dimensions would indicate a probable 5-watt rating; most likely carbon-comp. The coils are seven turns of what measures out to be 18 gauge. My LCR shows 0.3uh. I haven't swept them for a resonant point yet.
  Parasitic suppressors, maybe?

Just make sure they don't have any Ferrite in them, new chokes all seem to now.

73DG :P

  No ferrite in sight; the resistors appear to be very ordinary carbon-comp types. Still, I won't be trying them in anything big. I've got a couple of low powered transmitter projects envisioned in the near future, so they'll probably wind up in those.

I had the same question about the plate suppressors using two 100 ohm, 2 watt carbon resistors in my 3-500Z amplifier. Looks like yours will have a lower resonant frequency with more turns.  Model values: C1=285.4f, L1=500n, R1=410.1, R2=.1

I measured some parasitic chokes that were
used in a homebrew amplifier and they looked
something like this. Shown is S11, reflection
coefficeint from 1 MHz to 200 MHz. Their
response tends to follow a parallel line
with the real axis with increased
frequency and no clear resonance
point. The R component tends to dominate
and that is desirable. This plot from a
model, but close. The curvature really
flattens out and ideal, never crosses
over the real axis to the capacitive side.

Hi Alan,
Your S11 plot looks great, you would have crossed the real axis and achieved resonance
 if you swept higher in frequency. Here is the S11 plot of the 3-500Z plate suppressor for your comparison.

L =6 витков.диаметр намотки 10мм.длинна намотки 15мм ПЭВ-2  1.6мм
R=50 oм . C=68 пф

L = 6 turns. winding diameter 10 mm. winding length 15 mm PEV-2 1.6 mm
R=50 ohm. C=68 pf