It certainly is true that the ferrite core c.m. chokes have much more pure
resistance and are useful over a very wide range of frequencies compared to
a large coil of coaxial cable (a.k.a. air core choke). Each design has its
pros and cons. A lot of ferrite chokes experience significant heating
because of the pure resistance (which means they are working I guess) and
that may be okay for low duty cycles and power levels. As i mentioned
earlier, a long 160 m. coaxial cable coil has the loss of its long run. I
operate at a higher d/c and power level and have over heated some ferrite
chokes. Because I only needed functioning on one band and an air core does
not heat much, I used it. I maintain that if properly designed, they
perform at an acceptable level--I will grant you that I may have not made
mine well--but more important, the best choke is the missing one because it
is not needed. With an unbalanced monopole and ground system, you don't
need one if you have enough radials on the ground (roughly 30 or more).
73
Rob
K5UJ
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