Hi All: With respect to using un-uns, I found them to be reasonably low
loss through 50 MHz with type 61 cores, having built a dozen or so and
measuring back to back pairs of them on an HP141T for throughput loss. There
is an easy-to build (5) multi-match unun on pages 101~103 of Sevick's
"Understanding, Building, and Using Baluns and Ununs book with a 72~75 ohm
tap. Great book. Worth every penny.
I also used the 3/4 inch plumbing pipe versions with 9/32 hobby brass
center conductors from 144 MHz through 1296 MHz years back at my old QTH
(one hilltop away) and at W3KWH. I still have the quarter wave matching
section info originally from WA6MGZ in an old August 1982 Luner Letter
scanned in a jpg format if anyone cares to review. I probably have a few
quarter wave transformer VHF cut-offs up in the garage attic but it may be
easier to build clean new ones versus deox something 15~20 years old.
E-mail me at verizon.net with my call sign if the Lunar Letter info is of
interest. Mike wa3tts
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