[RFI] ethernet switch with shielded case or low emission spectrum

[Roger (K8RI)]

I hope this doesn't come through as a duplicate. My ISP changed the way 
they handle messages and one of my protective programs requires I OK the 
exceptions which dumps the mail requiring I do it over.

Be careful with wallwart power supplies.

I have used 8 port LinkSys and Netgear switches on a Gigabit network 
(Cat-5 wiring). I'm currently using a LinkSys Router with an 8 port 
Gigabit connection plus the 3 frequency wireless capability.  The past 
switches and the current router sit on top of the Emtron DX-2sp, or the 
Yaesu FTDX5000. 3 runs of the unshielded Cat-5 run with the coax cables 
to the 100' 45G for abt 75 feet. It's 130' run from the router to the 
shop computers. Neither the network or station appear to hear each other 
when the bands are dead quiet.

My approach for the last 30 plus years has beet to run cables where ever 
is convenient and "IF" there is a problem, THEN address the problem by 
fixing the source. There is no expertise involved AFAIK.  It's basically 
luck.  IOW the cabling behind the rigs and computers is a MESS. The only 
time I ever had a problem was when I tried to "neaten" up the mess while 
running multiple stations on multiple antennas.  It took me WEEKS to get 
rid of the interaction and cross talk and I was never sure I had all of 
the problems fixed.. I have never tried for neat wiring since then.

NOTE : Cat 5 and 6 do this intentionally by twisting signal wires at a 
rate to intentionally cancel cross talk (coupling) at the frequencies 
used. IOW you can normally bundle network Cat 5 and 6 cables together 
with little fear of coupling.

As for earth grounding, I do resort to multiple grounds. There is a 
daisy chain grounding the equipment chassis string AND an attempt to tie 
each piece of that equipment to earth ground through equal lengths of 
grounding cable as short as possible.  We are dealing with RF so The 
equipment isn't likely to see the short grounds as affecting the longer 
ones.  The same is true for lightning.  Where the 130' of Cat-5 ran 
through PVC conduit, induced voltages cost me a bundle with the 
Connectors being welded into one UPS, totaling one (state of the art)  
new computer and wiping out the NIC in a second computer.

There are two Caveats: Keep antennas well away from network cables and 
eliminate, or keep common mode RF on coax to a minimum. IOW, I use 
common mode chokes on most of the antennas!

For induced voltages (lightning protection) long runs of Cat 5 need to 
be in "grounded" metal conduit. Long runs of Cat-6 needs to have the 
shield grounded  at both ends.

73, Roger (K8RI)


On 3/29/2018 Thursday 2:22 AM, Jeff Blaine wrote:
> In the process of overhauling the shack's wiring, I'm wanting to 
> replace my existing ethernet switch with a box that is properly 
> shielded - or at least has one with a low emission footprint. Here i'm 
> talking about radiation from the box itself - not via the connected 
> ethernet lan cable runs.
>
> Unfortunately the houses' home-run location terminates a few feet from 
> my shack and so the switch needs to be located there.  I can apply 
> ferrite / common mode treatment to the power supply and lan cables 
> that connect to the box.  But I also need a box that is properly 
> shielded from a ham point-of-view.  The switches I have now are all of 
> the plastic-case variety and they all are pretty noisy.
>
> I was hoping someone may have found a "quite" switch that could be 
> recommended.  Some of the semi-pro (e.g. Netgear home-office rack 
> mount) stuff has metal cases -- but I don't know if that actually 
> means they are quieter.
>
> 73/jeff/ac0c
> alpha-charlie-zero-charlie
> www.ac0c.com
>
> _______________________________________________
> RFI mailing list
> RFI at contesting.com
> http://lists.contesting.com/mailman/listinfo/rfi


-- 
Roger (K8RI)


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