[RFI] Netgear GS724T switch

[nlsa at nlsa.com]

Dear Jim -
Thank you for your comments and suggestions.  I neglected to mention in my
original post that I had also replaced the Netgear switch's plastic AC power
entry connector with a shielded and filtered module.

Ethernet cables throughout the EME system are radiating both noise and
birdies, as you predicted.  This despite being shielded cables with shielded
connectors at both ends.  I'm at a loss how to bond the shield to chassis at
the point of entry other than using metal RJ45 receptacles and
metal-shielded RJ-45 plugs.

To "sniff" my EME system, I used an IC-202 portable 2m SSB transceiver and
hand-held 4-element 2m Yagi as an E-field probe.  RF radiation from Ethernet
cables is minor compared to the radiation coming from the switch itself.
The network switch is clearly the largest radiator even though its case is
steel, connector receptacles are shielded, and the AC line is filtered.

Rather than, "... try[ing] to fix a lousy product beyond choking stuff and
using proper cables," I'm going to change network switches.   Online
discussions seem to support Cisco Catalyst as being less noisy so I'll give
one of them a try.

Best regards,
Michael

-----Original Message-----
From: RFI <rfi-bounces+nlsa=nlsa.com at contesting.com> On Behalf Of Jim Brown
Sent: Thursday, June 22, 2023 4:55 AM
To: rfi at contesting.com
Subject: Re: [RFI] Netgear GS724T switch

On 6/21/2023 5:08 PM, nlsa at nlsa.com wrote:

More thoughts on this. Many years ago, Henry Ott reminded me that trash can
be radiated radiated by gear at both ends of every digital connection,
including Ethernet. That is, for most interconnects, both ends of the
circuit are transmitting. So all of the treatments applied to the Switch are
applicable to that gear.

Another thought -- have you choked YOUR gear? Have you studied shield
bonding in all of it? The last time I was at a ham expo (Visalia, 2019),
EVERY piece of equipment on display had Pin One Problems at EVERY entry of
cables other than the main RF I/O, so every control cable, audio cable, was
a source for RF in and out of the box. (A "Pin One Problem," 
first understood in the world of pro audio, is the failure to bond cable
shields to the shielding enclosure at the point of entry.)

Here in the Santa Cruz Mountains, I use WiFi to get around. I started using
that instead of wired Ethernet when I still lived in Chicago when I
discovered that the CAT5 was radiating trash that wiped out more distant
repeaters. The talkie probe showed me that it was ON those cables. Twisted
pair is great at minimizing that, but at some frequency, the twist ratio is
too low for the shorter wavelengths of VHF.

73, Jim K9YC
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