[RFI] 160 meter noise at W9RE tracked down to neighbors Comcast Cable Box / Power Supply

[Jim Brown]

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