[TowerTalk] W2DU Balun's?

[Greg Gobleman]

> Interesting -- I'd assumed Rich was referring to the W2DU bead choke type.
> I know they have some reported deficiencies at low frequency due to uneven
> heat distribution along the string of beads, but hadn't considered using a
> toroid and some teflon coax instead.  Has anyone measured the performance
> of such a choke balun at 160m?  What core material would be appropriate?
>
> 73, Pete N4ZR
>
I know we discussed this before, but, I have built several of the W1JR type
baluns.  I have 6 in various stages of construction.  I was never satisfied
with the enclosure for dipoles.  Didn't matter on a beam as it would be
affixed.  Just never have gotten back to them.  A fellow asked me sometime
ago about testing one.  I emailed him back to see if he wanted one in an
enclosure to test or just the core with the Teflon coax but I never heard
from him again.  I made two different types.  One for 10 thru 20m possibly
40m and the other a bit lower for 80m.  Didn't do one for 160.  I could do a
picture or two on the web if I can find a free hosting site.  I think my
memory is clear on the details.  Used Amidon cores and info from W2FMI's
book to do these.  Never observed any heating in the one I tested.  But
really didn't put it to the limit.  I was just doing these for myself, not
commercially.  Was kind of fun and I ordered 6 cores just to make it
worthwhile.  I have to go down in a while, I snag the info off them.  I'm
not very scientific here, just a typical Joe ham.

Oh yeah, lots of good baluns out there, but I have seen heating in the W2DU
and W2AU.  Got lots of loose beads in a drawer from a blown-up W2DU.

Greg K9ZM



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