Jim - I can vouch for the fact that the portion of your post I've included
below is very true. I was quite surprised to find that the jacks/sockets on
the rear of my Icom 781 and 765 were NOT grounded to the chassis at that
point. Indeed, the ground lead often passes as a trace across the circuit
board onto which the jacks are mounted before they are grounded, and most
often the ground lead does is not connected to chassis ground until the
cable reaches the destination board. On my 765, the ground trace for the
external speaker jack was blown off the board so cleanly that you had to use
a magnifier to tell where it had been originally. A similar problem
occurred with the Remote jack (PC control connection). In the case of the
765, I at least had a simple symptom - no audio out. With the Remote jack,
the communications with the PC became intermittent since there were other
ground paths for the signal, but then substantial noise was picked up on the
Remote line.
K8AC
----- Original Message -----
From: "Jim Jarvis" <jimjarvis@comcast.net>
To: <kd4e@verizon.net>; <towertalk@contesting.com>
Sent: Saturday, February 26, 2005 12:51 PM
Subject: [TowerTalk] lighting "umbrella"
<<snip>>
> Incidentally, if you leave the radio connected to power and
> RF GND,
> whatever potentials exist between the RF gnd and the power gnd are
> impressed
> across the ground traces in the radio...and power and RF are undoubtedly
> kept separate
> for EMI/EMC/noise reduction purposes.
>
> Just a thought.
>
> n2ea
> jimjarvis@ieee.org
>
>
<<snip>>
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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