[Elecraft] K3: Are the birdies really birdies

[Tim Tucker]

I long ago diagnosed several of my RFI problems on ethernet devices
throughout the house.  I tried everything to get rid of it including making
special ethernet jumpers I put at the source devices with ferrite and
by-pass capacitors between the offending pair of wires (the TX/RX wires).
Of course the caps worked, but since the ethernet signal is AC, it also
killed the network, LOL!

Shielded cable on long runs that is grounded at both ends definitely makes a
big difference...at least it did for me.  It doesn't get rid of it entirely,
but it helps.  Some devices are worse than others, and of course it's more
pronounced on some bands than others.

On Tue, Nov 16, 2010 at 4:05 PM, Kok Chen <chen at mac.com> wrote:

>
> On Nov 16, 2010, at 3:02 PM, Mike K2MK wrote:
>
> > Moving the shack CAT 5 cable away from other radio related cables is
> having a positive effect. Next I'm going to try a shielded CAT 5 cable from
> the wall to the shack PC.
>
> I can attest to the effectiveness of shielded Ethernet cables (for me
> anyway).
>
> After fighting with Ethernet noise, I finally swapped out all the Ethernet
> switches in the house with ones that have metal enclosures (Netgear GS
> series), and replaced all UTP CAT-5 cables to STP CAT-6 cables.  The
> shielded switches by themselves didn't do much until I went to the STP
> cables.
>
> I couldn't find shielded CAT-5 at the local Fry's and just went with CAT-6.
>
> I believe the critical difference is STP (shielded twisted pair) vs UTP
> (unshielded) and not the difference of going from CAT-5 to CAT-6.  If you
> can't find shielded Ethernet switches, perhaps at least look for ones where
> the RJ-45 jack has the metal tab that connects to the shield of the STP CAT
> cable.
>
> I still have a box full of unshielded CAT-5 cables that I have been using
> for controlling remote antenna switches and such :-).
>
> Going to WiFi can also help, but some WiFi routers, like the early Apple
> Airport Express, are themselves very RF noisy in the HF region.  I don't
> know if the newer AirPort Express are any better since I had banned the
> Apple AirPort Express from this QTH :-).
>
> 73
> Chen, W7AY
>
>
>
>
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