[TowerTalk] Interconnect Cables

[Jim Brown]

On 7/11/2013 5:19 AM, Pete Smith N4ZR wrote:
> but as I get older, I get more and more impatient with time wasting. 

I've found that my tolerance for BS has dropped a lot too. :)

> What I really should do is go through all of the cables I'm using with 
> an ohmmeter and discard any that are dubious.  On a pre-made USB to 
> Serial adapter, for example, I presume I could make a small slit in 
> the serial cable and ascertain whether a) there is a shield and b) it 
> is connected to the shell of the DB-9.  Same presumably could be done 
> on USB cables, at least for presence of a shield and continuity with 
> the ground lead. 

Yes, that would be a good move.  I make up all of my own cables for 
several reasons. First, most pre-made cables have really crummy shields 
(if they have shields at all -- I've cut up some cables and found a 
single wire, or a very flimsy imitation of a braid).  I use either 
miniature coax (RG174, etc.) or RG58 for unbalanced audio. Second, 
twisted pair provides FAR greater immunity from RFI or noise coupling 
that parallel conductors, and most pre-made cables use parallel 
conductors. CAT5/6/7 is EXCELLENT twisted pair. Third, I'm VERY 
concerned about where the unbalanced signal return is connected, 
especially if there is no shield. If there is no shield, the unbalanced 
return must go to the chassis.

73, Jim K9YC