[Elecraft] KPA500/KAT500

[Jim Brown]

On Thu,9/17/2015 10:15 AM, G4GNX - Alan wrote:
> It may have sounded ignorant, but I was concerned that there might be 
> RFI and RF in the shack issues, although I couldn't see how MFJ 
> allowed for this and they obviously don't. :-)
>

ANY long wire that ends in the shack puts RF in the shack. That's how 
antennas work. If it didn't put RF in your shack it would be a lousy 
antenna. The key is to RF-proof the gear in your shack.

When I operated from a wood frame 2-flat in Chicago, I had a dipole fed 
with vintage 75 ohm KW twin lead made by Belden (long discontinued). On 
80 and 160, I tied both sides of the feedline together and loaded it as 
a long wire, using a about 150 linear feet of wrought iron fence as a 
counterpoise. By virtue of the length of the wire and the counterpoise, 
there was a lot of RF current in my shack, so it coupled inductively to 
nearby wiring, including the serial cable running from my laptop to my K2.

This coupling occurred because the serial cable was parallel wires, and 
it caused the computer keying circuit from computer to K2 to lock up 
with as little as 12W. When I replaced that cable with CAT5 (which is 
four very good twisted pairs) using one pair per signaling circuit, the 
coupling went away, and I could run my Titan amp at full power with no 
problems.

73, Jim K9YC