On Wed, 02 Feb 2005 15:09:14 -0500, Jon KB1HTW wrote:

I need to extend the control cable for my AH-4 tuner. I have lots of Cat 5
Ethernet cable. The four leads to the tuner are Key, Start, +13.8Vdc, and
Ground. I initially hooked up each to each of the four pairs in the Ethernet
cable (i.e., Key to Blue/Blue-White). My thinking was parallel each pair so
I have less current loss, but I think I blew the capacitance out of the
water and the Key/Start pulses are getting smeared along the 100+ foot run.

What's the best way to wire things up so to the twisted pairs so any RFI
gets nulled out? Ground to each of the 4 White leads, and Key to say Blue,
Start to Green, and +13.8V to Orange? That way each twisted pair would have
a "signal" and ground. Or I could use the Brown for Ground, and connect the
AH-4 factory cable's shield to the four white leads. Which is the preferred
route for minimizing RFI or cable capacitance affecting the Start/Key pulse
signals?

Jon - KB1HTW

Try using a shielded 4 conductor cable. All the stuff about ferrites is
good but if you can prevent pickup in the first place, that is better.
Also try ferrite beads on the ICOM interface control wires inside the
tuner.