[Elecraft] Is the KIO2 line needed with external amp and auto-tuner?

[Jim Brown]

On Fri, 06 Mar 2009 18:04:04 -0500, Don Wilhelm wrote:

>If I recall, the signaling has been tested out to 6 feet of cable, but 
>it sounds like your plans will require more cable length than that.

The primary issues with cable length are noise pickup and capacitance. 
Both can be helped a lot by using CAT5 for the serial connection. Dedicate 
one pair to each signal line, and connect the return of each pair to the 
connector shell, not pin 5.  CAT5 is very low capacitance, and the very 
high twist ratio rejects noise and RFI. Going to the connector shell 
bypasses the pin 1 problem at each end. 

I work in pro audio, and we often have sound equipment in racks buried in 
the bowls of the building, but need to remote control that gear for tuning 
the system from within the auditorium. Doing what I've described, we often 
use serial over 200 ft of CAT5 at very reasonable data rates with no 
problems. BTW -- the RS232 standard originally quoted cable length as a 
limit, but was later revised to define it on the basis of capacitance. 

73,

Jim Brown K9YC