Jack:
A Unun can be wound top match 50-ohms to 34.7-ohms, and in fact
Bytemark has several ratios available from Amidon if you don't want
to wind it yourself.
http://www.bytemark.com/amidon/prunun.html
Winding information is in ON4UN's book, or in Jerry Sevick's
book "Building and Using Baluns and Ununs". ARRL or Bytemark
have the book. Sevick had information in a number of articles
in QST in the 70s and early 80s, in his excellent series on
short vertical antennas.
http://www.bytemark.com/amidon/prbooks.html
When I was playing with my inv-L and wasn't sure what ratio I was
going to require, I purchased the Amidon model W2FMI-HMMU50,
which allows you to match 50-ohms to five output impedances:
34.7, 22.2, 12.5, 8.68, and 5.56. It handles a full KW, and I left
it at the base of the antenna through a Winter before I replaced it
with a dedicated Unun. Bytemark sells it for $70. This unun is
documented in Sevick's book as well.
73,
Jeff Maass K8ND
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