"Jeff" wrote in message
...
Hi Guys,
Results of the build and test were that the 7Mhz HPF worked very well with
the "6" grade cores, but the 20Mhz LPF was crap (it used #6 as well). It
started to roll off at 20Mhz as expected, dropped smoothly to -10dB by the
time it got to 40Mhz, then stayed at 10dB at all frequencies above 40Mhz.
I suppose the core should be a grade #10 or #12 instead of #6? or perhaps
just a normal air core?
JEFF

Then you haven't built the filter that you designed. The choice of core
material will not affect the blow-by. If you measured the inductors at a low
frequency, I would be pretty certain that you have way too much inductance
at 20-40 MHz.

W4ZCB