[Elecraft] K3 Audio/RFI Feedback

[Jim Brown]

On Tue, 19 Jan 2010 14:57:16 -0500, Joe Subich, W4TV 
wrote:

>Improve the grounding of your station, 
>including direct grounds on both the K3 and computer 
>to the common ground point and add common mode chokes 
>to both your feedline and the "Line In" connection to 
>your computer. 

I agree with the advice, but I would not CALL it 
"grounding" -- that implies ground rods and all that 
mess. Rather, it is BONDING. It is unlikely that a 
connection to EARTH is part of a solution. BONDING is 
simply a very short, beefy copper connection between 
the CHASSIS of all of the equipment. Most important is 
between the chassis of the K3 and the chassis of the 
computer. 

See http://audiosystemsgroup.com/HamInterfacing.pdf  

And yes, a beefy coaxial ferrite choke as close as 
practical to the feedpoint of your antennas, and 
ferrite chokes on those audio interconnections. Those 
chokes must be wound so that they are resonant where 
you are having problems. Follow the guidelines for 
coaxial chokes in my Choke Cookbook in 

http://audiosystemsgroup.com/RFI-Ham.pdf

and use the measured data in Appendix One for small 
wire chokes as a guide for chokes on the audio lines. 

Little clip-ons will not solve problems on 80M. You 
need lots of turns. 

73,

Jim Brown K9YC