[CQ-Contest] Ferrite bead mixes?
k4ro at music-city.tdec.state.tn.us
k4ro at music-city.tdec.state.tn.us
Mon Jan 5 19:19:35 EST 1998
I know some of this was hashed around in the past, but I could
not find a definitive conclusion anywhere. What is the best mix
of beads to use on the 6 HF contest bands? Here's is what I've
gathered so far:
- Type 77 chokes better than 43, epsecially at lower frequencies
- Because it chokes better, 77 gets warmer, sometimes apparently
to the point of damaging coax
- Sometimes a teflon coax pigtail is used to deal with the heating
(but this adds yet another connector junction to the feed system...)
- Some have proposed the idea of mixing type 43 and 77 beads together
- Six (6) beads seems to be the nominal number used at a feedpoint,
with sometimes even higher numbers on 160 & 80.
Questions:
Is six beads a good number to use? What do you use for which bands?
Has anyone used both type 43 and type 77 beads on HF, and can offer
a comparative analysis?
If mixing the types, what would be the best method and numbers?
Some possibilities: a) three #43 beads right at the feedpoint with
three #77 beads right benind it (43-43-43-77-77-77) or b) six mixed
"interlaced" beads (43-77-43-77-43-77.)
Tracy at Amidon had no suggestions, and their WWW page was not
yet completed in the areas relating to these products. (Charts
and graphs with the info I wanted were missing, although there
was a "stub" pointing to them.)
Thoughts? Thanks.
-Kirk K4RO
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