[RFI] Holiday RF Mixing

[Jim Brown]

On 11/27/2024 6:03 PM, Bob WA2SQQ wrote:
> Replacing the custom cable
> with the original one or omitting it did remove the interference, but why
> did previously work? Charlie reached out to Verizon who sent a tech out.

I suspect that Verizon's installation, whatever it is, may have 
exploited a vulnerability in the way the cable was built and/or wired. 
The first question I would ask is for a detailed description of that 
cable. How many conductors, are they twisted pairs or parallel wires, 
does each circuit have it's own return? Is it shielded? Where is the 
shield connected on each end?

The keys to something like this working or being problematic is whether 
or not the signals are carried on transmission lines or on wires, and 
where the returns (if there are any) are connected. CAT5, for example, 
is NOT 8 wires, it is four tightly twisted pairs. Twisted pair is FAR 
more resistant to interference and crosstalk than constructions like zip 
cord, regardless of of the size.

73, Jim K9YC