On 2/23/2020 5:12 AM, Don Kirk wrote:
I have to tell you that when working in someones house that is not a
hams we should not be installing anything special if at all possible
(unless it's indeed one simple choke on the power cord and that's even
pushing it). We should first hold the company that installed or
supplied the hardware responsible for a clean solution. In this case if
it's the switch mode power supply, then Comcast can easily provide them
a different power supply or a different Cable box that uses a different
power supply to see if that fixes the problem.
Hi Don,
I completely agree with everything you've said, especially about holding
Comcast's feet to the fire on this. BUT -- it is VERY, VERY unlikely
that they will 1) understand the problem and 2) have a solution.
If I were dealing with a cooperative neighbor like the one you cite, I'd
return with a choke wound with RG6 connectorized to plug into the modem,
and a few more clamp-ons to choke other cables. If there are CAT5/6
cables connected to it, I'd have some of those cables wound through
cores to replace the existing.
There's a LOT of great advice and ideas/comments in the rest of this
thread.
As to the value of SDR waterfalls -- it's another VERY important tool in
our kit. The spectrum and waterfall can tell us the generic type of
source we're looking for -- is it 1) a power control device like SMPS or
variable speed motor controller; 2) backhaul leakage from cable system
like what is shown on page 2 of the link I posted last night; or 3)
something arcing. #1 and #2 must be chased on the frequencies where we
hear the noise, #3 must be chased first at lower frequencies, then at
the highest possible frequencies.
73, Jim K9YC
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