[Elecraft] K3: 6M SSB audio hash

[Jim Brown]

On Sat, 7 Jun 2008 09:08:59 -0500, James C. Hall, MD wrote:

>This is all very interesting. What do you see as my solution ? Do I need to
>add a ground in some way to the cable ?

I missed the details of exactly what you are trying to connect to what. As I 
understand it, you are trying to connect an unbalanced mic to a balanced input. 
The proper connection for that is to connect the two mic wires (the hot and the 
shield) to the balanced input AND to connect the shield DIRECTLY TO THE CHASSIS 
by a very short path.  

Many products are manufactured in such a way that what I have described is 
difficult -- the shield connection goes to the printed circuit board, wanders 
around a while, and eventually finds the chassis. This is called a Pin 1 problem 
(because it was first well understood in the pro audio world, and pin 1 is the 
shield contact of a pro connector), and it is a MAJOR cause of hum, buzz, and 
RFI. 

If the cable shield does not go straight to the chassis, it cannot function as a 
shield. If it has a long (inductive) path to the chassis, it provides a VERY 
strong path for RFI into the box. See the tutorial on my website, cited in an 
earlier email.  

73,

Jim Brown K9YC