Paul,
I'm outta town for the weekend and away from references. However, from
memory, there really isn't one formulation of ferrite that will work at
OPTIMALLY at Longwave up through 30 MHz. Generally, Bill Bowers and I shot
for
really good performance from 5 MHz. down. The problem tends to be at
the lower frequencies, where performance can drop off like it was shot. My
impression is that upper frequency performance is much more forgiving.
I believe that there are two impedance matcher articles on dxing.info. Be
sure that you are reading the latter one, if you only read one.
John B.,
