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
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