[Elecraft] RS-232 Cable Question

[Jim Brown]

On Thu, 18 Mar 2010 14:52:28 -0700, Jack Brindle wrote:

>The computer cable for the K2 requires only three wires connecting  
>pins 2, 3 and 5 on each end. 

For any serial cable used in a ham shack, including this one, you should 
use twisted pair cable for each circuit to minimize RFI susceptibility. I 
learned this the hard way in Chicago, when my 160M/80M TX antenna was a 
long wire ending in the shack.  

The best, most readily available twisted pair cable is CAT5. Shielding is 
NOT important. It also helps to terminate the return for each circuit to 
the connector shell, NOT to pin 5. This bypasses the "pin 1 problem" 
common to most serial interfaces. 

For detailed info on how to build this serial cable, see 

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

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

The stock K2 cable, made with shielded parallel conductors, locked up 
keying from the computer with less than 10 watts out of the K2 running 
barefoot. The cable I made using CAT5 allowed me to run full legal power 
with my K2 driving a Ten Tec Titan to legal power. 

I told Wayne about this more than five years ago, but last I heard, the 
K2 cable is still made with straight parallel wires. 

73,

Jim Brown K9YC