On Wed, 25 Jul 2007 18:04:21 -0700 (PDT), Rick Karlquist wrote:
>inductance no longer goes up as N squared.
It doesn't matter -- it's RESISTANCE we want, not inductance.
But 6 meters IS a challenge for a choke balun (it's also quite a
challenge to measure). As Jim Lux suggested, a multi-turn choke
WILL work, but you'll need several chokes in series. A study of
the data in the updated tutorial should help you design a suitable
choke.
A traditional "string of beads" choke using #31 or #43 cores will
work fine on 6 meters. Probably the best bet is a string of two-
turn chokes using a short length of smaller coax (like RG8X)
through a 0.45 i.d. core designed for RG8. One of the 1 inch long
#31 or #43 cores should yield about 600 ohms on 6 meters. I would
use at least six of those in series on the coax, with a separate
2-turn loop for each.
If you want to use RG8, use two of the "big #31 clamp-ons" listed
in the tutorial, each with three turns through it. Each clamp-on
needs its own 3-turn loop.
When counting turns, that's the number of times the coax passes
through the cores, not the external turns.
For more details, see the tutorial.
http://audiosystemsgroup.com/RFI-Ham.pdf
73,
Jim Brown K9YC
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