[Elecraft] Interference from Computers-Routers

[Kevin Wood]

>> Has anyone on the reflector had such a problem and found a way to cure
>> it?
>> Searching on the internet I find that RFI from routers is a well known
>> phenomenon, but I have seen no suggestions for curing the problem.

FWIW I found that using shielded twisted pair (STP) ethernet cables rather
than the more common unshielded twisted pair (UTP) helps. STP cables have
a foil shield over the pairs of cable which is grounded to the equipment
chassis by a metal outer on the RJ45 connector.

It's still worth putting a ferrite on each end of the cable.

I've got a Draytek broadband router that puts out loads of QRM right over
the HF bands and beyond 2m. When I had a look inside I found it's got a
PCB containing a switching regulator, a fast CPU and the line transceiver
for the ADSL. This just sits inside a plastic box with no attempt at
screening whatsoever. I think the fix is going to be to put the whole lot
into a larger metal box and filter the connections in and out.

Needless to say, a product to avoid if you value a quiet electrical
environment!

Putting a wireless LAN router in a metal box probably defeats the object
of having it, unless you can wire the antenna to an SMA connector on the
outer box, I suppose.

Finally another source of noise I find is video cables connecting cable /
satellite set top boxes to TVs. Here you get a signal with strong 50 / 100
Hz components (OK. 60/120Hz for most of you I guess!) that varies in
amplitude with the brightness of the picture.

Hi to all (first post here). K2 kit on order...

Kevin
G7BCS