[RFI] Single-point grounding

Sun Jul 1 07:58:48 PDT 2012

That would seem adequate... I just run a piece of 4/0 wire around the
baseboard and go up the back of each operating table with a piece just hose
clamped to it then unwrap strands to go to the radio, amp, computer, etc on
each table.  I used to have problems with 10-base2 coax Ethernet but never
have had a problem with rs-232 radio control lines.  

David Robbins K1TTT
e-mail: mailto:k1ttt at arrl.net
web: http://wiki.k1ttt.net
AR-Cluster node: 145.69MHz or telnet://k1ttt.net

-----Original Message-----
From: Pete Smith N4ZR [mailto:n4zr at contesting.com] 
Sent: Sunday, July 01, 2012 14:29
To: RFI List
Subject: [RFI] Single-point grounding

I'm not sure exactly where I should post this, but suspect that this group
probably has more relevant expertise than most, so please bear with me.

In the last year, I have had two expensive episodes.  In both cases, my
transceiver's RS-232 transceiver was fried during a lightning storm, and
several knowledgeable people suggested a difference in chassis potential
between computer and transceiver as the reason.  Their prescription for
avoiding a repetition was simple - connect the chassis of all of the units
to a single-point ground.

My solution - which I'm asking people to critique - was to fabricate an
L-shaped, roughly 3x5 foot ground bus made from 3/4" copper tubing, which I
mounted on the back of my L-shaped operating desk. All joints are
silver-soldered. I then connected each of the affected units to the bus with
very short and heavy stranded wire, and connected the end of the bus to my
grounded shack entry panel (in a double-hung window).

The DC resistance of the ground bus is very low, but the length approximates
a quarter wave on 10 meters, and with the units connected near the ends of
the bus, I wonder if I'm feeling a false sense of security about the likely
behavior of the bus during a nearby lightning event.  Would I be better off
(or no better) running heavy conductors from each unit to the entry panel,
even if they would have to be similarly long? Or should I just give up and
plan on disconnecting the
RS-232 connection whenever weather approaches?

73, Pete N4ZR
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