On 6/21/2023 5:08 PM, nlsa@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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