On Sat, 29 Aug 2009 16:59:43 +0100, Doug Turnbull wrote:
>Thank you for this thought provoking e-mail. I had never thought of
>using a common mode current choke.
I strongly agree with Pete. See the Choke Cookbook in my RFI and Ferrite
tutorial for more advice on winding the chokes.
http://audiosystemsgroup.com/RFI-Ham.pdf
Fair-Rite's #31 materials is FAR superior to their #43 material on 160M.
See the data (measured) and the text to understand why. I don't know of
an equivalent to #31 from any other ferrite vendor. Fair-Rite does have
distribution in EU, but I don't know how accessible it is for small
quantities. The US distributors listed in Appendix One are easy to deal
with for medium quantites, but I don't know if they do export biz.
>Is this choke mounted at the K9AY or close to the shack?
At the K9AY. If it's a long run, (mine are) another choke at the shack
decouples the feedline from the TX antenna (which is close to the shack)
and its radials. BTW -- my RX antennas are Beverages, but the principles
are the same.
73,
Jim Brown K9YC
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