[Fourlanders] Contest Computer RFI

[Rogers, Ron]

Another thing to think about in reducing the amount of localized RF in
or around the equipment is the fact that we DON'T GROUND ANYTHING and
everything is just "floating".

Yes, it is difficult to find a decent way to ground the trailers, the
Ethernet hubs being used, etc. But it is worth brainstorming to see what
we could do. The high speed, high impedance differential line-driver,
line-receiver amplifier circuits used in those hubs are simply packaged
in their plastic cabinets with no shielding (I suspect). In any case, I
know there is no frame grounding and simply have 2 wire "wall warts"
powering them which means not even a having frame ground brought out to
an "Earth Ground" pin. 

We old-time repeater builders designing equipment for mountaintops with
lots of 500 watt pagers and 2-way systems have learned by our share of
"hard knocks" how important some of these small details are.

Also, the suggestion of switching Ethernet gears down to 10 Mbs may have
merit and should be tried.

I'll also be shopping around for some more of the clamp-on ferrite cable
"decouplers" we use on some of our NCR equipment. I've had to install
some of the same type on my RS-232 4800 baud cables at the Sawnee
Mountain repeaters site to maintain reliable low speed RS-232 comm
between the multiple repeater controllers and the "modem gateway"
computer. We run Win Laplink on that computer to provide remote console
programming capability of the repeaters at the QTHs of the repeater
technical support people.     

Ron
WW8RR