Topband: Inverted L Matching

[Jeff Maass]

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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