[Elecraft] [K3] birdies and cable routing?

[Geoffrey Mackenzie-Kennedy]

Ed,

Double-shielded coax would most likely not make much if any difference to 
the level of birdies if the coax cables pass over or are close to an 
unshielded pcb, or some other unshielded source involved in generating a 
birdie. If moving the coax cables affects the level of birdies, then the 
outers of one or more cables would appear to be one path involved in the 
generation of birdies, and using double-shielded coax would only move this 
path to the outside of the second (added) braid of the coax.

Not an "exact science" but there are some fundamental rules.

73,

Geoff
GM4ESD


----- Original Message ----- 
From: "Edward R. Cole" <kl7uw at acsalaska.net>
To: <Elecraft at mailman.qth.net>
Sent: Wednesday, September 08, 2010 7:35 PM
Subject: [Elecraft] [K3] birdies and cable routing?


> John,
>
> As Wayne has stated, routing varies with individual radios, so what
> works for one may not be optimum for others (definitely a trial and
> error process).  A though occured to me, though.  Since cable layout
> seems to make a difference for some, I wonder if double-shielded
> cables would make any difference?  That would only if leakage is
> occuring.  If birdies are being conducted over the coax shields
> (common-mode) then perhaps a few ferrite beads would help?
>
> This stuff is in the area of "magic touch" and hard to reproduce as
> "exact science".
>
> 73, Ed - KL7UW