TT:
Been reading Bill Meeker's OCF dipole saga, and communicating privately with
him.
Jack Belrose, VE2CV, wrote a series of articles for QST over 10 years ago,
analysing the OCF dipole, and designing a 'balun' to handle the varying complex
impedance presented by the off center feed.
In reality, what is needed is an "un-un", and Sevick's work may prove helpful,
as well.
For whatever value it may have, I was inspired to try an OCF dipole by Belrose,
as a general purpose antenna. To save time, I used a commercial
product....the "Carolina Windom", of which I've now had several, in both 160
and 80m configurations. Radioworks makes and sells these things, and has
resolved the matching solution to a satisfactory degree.
As both K4SAV and W8JI observed, an unbalanced antenna will tend to have
current on the outside of the feedline. The CW is no exception. My solution
is use of ferrite chokes in the feed system, on a ground point directly below
the antenna. The coax shield is grounded through a bulkhead connector
fastened to the ground rod. Clip on ferrites both upstream and downstream of
this point tamed the common mode problem.
N2EA
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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