I forgot to mention that I used an Amidon Balun to feed the Driven element
of the Yagi-The original obtained 50 match by careful tuning, and the use of
a 1-1 balun.. After I constructed the thing I measured the Driven El.
impedance using a noise bridge. with the ant. on top of a stepladder. it was
about 13 Ohms (like the ant. book says)- I saw an ad for baluns by Amidon
(W2FMI) -They had one that goes from 50 Ohms unbal to 12.5 ohms Bal. so I
bought one and stuck it on...
Since then I bought an MFJ swr analyzer, and measured it at the shack
end of the feedline, it reads 47 ohms resistive.. It can be matched by
tuning, but the 50 ohm unbal to 12.5 bal will make life much easier.. I
expect that it will go to 50 ohms when raised up to 30 feet or so.... '73
Jim W. K1EXE
--
FAQ on WWW: http://www.contesting.com/tentecfaq.htm
Submissions: tentec@contesting.com
Administrative requests: tentec-REQUEST@contesting.com
Problems: owner-tentec@contesting.com
Search: http://www.contesting.com/km9p/search.htm
|