Don't have any experience with that hardware, nor with very weak signal
2M. Several thoughts/questions. First, exactly what ferrite parts (what
mfr and mix, part numbers) and how many of them on each cable? Anything
on the power cable? Is the box shielded?
Have you tried probing around the box with a 2M talkie for noise? Trash
is most often conducted to cables and radiated by them due to poor EMC
design, which can include proper bonding of cable shields (which MUST be
to the shielding enclosure at the point of entry). Power cables are a
common problem, as is proper filtering and bonding of power connectors.
Trash is also radiated from internal circuitry as a result of poor
circuit design, especially bad layout of PCBs, combined with shielding
failures. Some common ones are painted pieces of enclosures that don't
make contact, conductors that come through enclosures that aren't either
bonded to it at the point of entry or effectively bypassed to it.
Probing with the talkie can reveal a lot. My general rule to never try
to fix a lousy product beyond choking stuff and using proper cables.
I'd also poke around with an ohmmeter to see if you get dc continuity
between the shields of those STP cables. They could still be badly
terminated if there is continuity, but no continuity would tell you that
they're not terminated at all!
To reduce sensitivity of the talkie, replace the duck with a paper clip
(or even no antenna at all).
73, Jim K9YC
On 6/21/2023 5:08 PM, nlsa@nlsa.com wrote:
Dear friends,
My remote 2m EME system is comprised of a number of modules (SDR,
transverter, SSPA, plus antenna and ventilation control modules, etc.), all
of which are linked to each other via a Netgear GS724T Gigabit
<https://www.netgear.com/business/wired/switches/smart/gs724tv4/> "smart
switch." All this equipment is located right underneath the EME antenna.
Despite abundant snap-on ferrite chokes and use of STP Cat6 cables
throughout, there is still considerable EMI from the switch and the Ethernet
cables connected to it. Is there more that I can do to quiet the switch?
Alternatively, is there a network switch that is known to be RF-quiet?
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