> 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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