[RFI] router RFI

[Jim Brown]

On 3/3/2013 9:51 PM, N1BUG wrote:
> This particular carrier needs to go away, if possible. It is at the 
> home of our county EC and ARES coordinator. Our ARES repeater happens 
> to be on 147.210.

Hi Paul,

Several thoughts.

First,  Dale noted a similar carrier at 147.39, and we know that 
Ethernet birdie frequencies are driven by the fact that each Ethernet 
switch is free-running with its own crystal controlled oscillator. SO -- 
changing out the physical switch (which may be part of a wireless 
router) could move the birdie off of 147.21 MHz.

Second, a case could clearly be made that this device, wherever it is 
located, is interfering with licensed radio communications, and Part 15 
could be invoked to persuade its owner that it must be fixed.

Third, if the device can be located, my guess is that it MIGHT be 
sufficiently suppressed by a 4 - 6 or so 1-inch long #43 cores on each 
cable connected to it, and to the other end of Ethernet cables connected 
to it. That won't help, of course, with stuff radiated by the box itself.

When thinking about problems like this, it helps to think about HOW MUCH 
suppression is needed. Those cores aren't going to get you 40 dB, but 
they might get you 10-20 dB, and that might be enough.

I'm assuming you've already determined that the bad box is not his own 
(by killing power to it).

You might be able to fox hunt the source with a 2M talkie. When 
participating in our annual radio club fox hunts (the North Shore Radio 
Club in suburban Chicago), I learned that I could make my talkie's 
rubber duck directional by holding it close to my body to block it from 
one direction. And when I got close enough, I added an attenuator by 
removing the duck.

73, Jim K9YC