On 7/29/2013 10:07 AM, Brian Sarkisian wrote:
Any help would be appreciated.
In addition to the advice that both W8JI and I have offered about
switching power supplies, don't overlook radiation from, and reception
by, the telephone line. This mechanism is greatly increased when the
telephone cable utilizes parallel conductors rather than twisted pair,
and is interference is considerably reduced when the the twisted pair
has a very high twist ratio (more twists per inch) and a more uniform
twist.
For more than a century, telegraph and telephone wiring VERY effectively
used twisted pair to reject interference, but the bean counters took
over, and local wiring now uses a lot of parallel wire cables (because
they are cheaper). In ALL cases of interference involving telephone
systems, one of the first moves should be to replace parallel wire
cables with CAT5/6/7 cables, ALWAYS dedicating a pair per circuit. In
CAT5/6/7 cables, Blue and Blue/White is a pair, Or and Or/Wh is a pair,
and so on. Most of this wiring belongs to the telephone carrier, and it
is THEIR RESPONSIBILITY to make this replacement.
Likewise, when ANY product is the cause (or victim) of RF interference,
we should ALWAYS DEMAND that the vendor solve HIS problem, which is
ALWAYS the result of poor engineering of domination of the manufacturing
process by bean counters. Several years ago, I saw a post by W8JI that
he had done exactly this to solve a DSL RFI issue.
When ANY baseband system receives RFI, or CAUSES RFI, it is defective,
and should be returned for replacement or refund. As I learned in the
civil rights movement 40 years ago, if you're not part of the solution,
you're part of the problem.
73, Jim K9YC
Still working on solving the root cause of problems :)
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