[RFI] router RFI

[Cortland Richmond]

On 3/4/2013 1257, Jim Brown wrote:
> ... 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. ;;;
Some 14 years ago, IIRC, I was sent to Elmhurst IL on an EMI complaint; 
a pairgain unit* there was interfering with a local Ham on 2 meters. 
Without getting into too much detail, the source was a 1.024 MHz clock 
and fixable by one of two simple methods, one of which was already 
entering production.

* Example: http://www.charlesindustries.com/images/i_te_dualine2.gif

Of interest to this thread:
The (non-Ham) engineer who'd gone there before me had left (in all) 
forty-two clamp on 1X1.5 inch ferrites on the line and loop wiring, 
which made, so far as I could tell with a spectrum analyzer and 
bi-conical antenna, *perhaps* ONE dB difference.

FAR better to fix it on the board.

Cortland
KA5S