[TowerTalk] K9AY performance expectations/help

[Jim Brown]

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