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Re: [TowerTalk] Fwd: Grounding of tower

To: towertalk@contesting.com
Subject: Re: [TowerTalk] Fwd: Grounding of tower
From: K8RI <K8RI-on-TowerTalk@tm.net>
Date: Fri, 10 May 2013 19:50:16 -0400
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
On 5/10/2013 4:04 PM, K1TTT wrote:
A corollary to this is:  There is no such thing as a ground for lightning.

You can kind of get away with pouring a bit of household 60hz

I almost got killed doing that

The station, a Yaesu FT101B, was on the East end of the South side of the basement with a ground rod about 4' to the South. The 40 m vertical with radials was about 50 - 75 tied to an 8' ground rod at the base feet West of the house. The house electrical ground was about half way between. The soil was quite moist.

The radials laid on the ground and had about 4-5 inches bent 90 degrees at the ends. It was spring and several of the radials had come loose and curled up.

I pulled one straight and knelt down to stick the end back into the ground. Remember the other end connected to a ground rod which was connected to the rig through the braid. Neutral connected to the house ground at the panel and the rig at the outlet.

When my knees touched the ground, it had me. My muscles just clamped up and I curled up. The only thing that saved me was when I curled up, I fell over backwards and my knees broke connection with the ground. As soon as I was free I threw that wire<:-))

Unbeknownst to me there was an overly generous solder joint on the power connector. It looked like an over size Jones connector. The chassis side had a ball of solder on one pin that could touch the chassis if there was just a little side force on the power cord.

My Simpson showed just over a 100VAC from the ground rod and sticking the other lead in the ground as far out as it'd go which was about 6 feet.


73

Roger (K8RI)


into the
ground, but don't count on it to work for a primary on a power line either!

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


-----Original Message-----
From: Jim Brown [mailto:jim@audiosystemsgroup.com]
Sent: Friday, May 10, 2013 17:17
To: towertalk@contesting.com
Subject: Re: [TowerTalk] Fwd: Grounding of tower

On 5/10/2013 9:29 AM, George Dubovsky wrote:
3. "RF ground system" is a perfectly good term and is accepted and
understood in the rf design community.

I strongly disagree -- it has led to HUGE misunderstandings and TERRIBLE
errors in the construction of equipment that are so widespread that they are
accepted as the only way to do it, and are a major cause of hum, buzz, and
RFI.  It causes people to think that ground rods are a desired part of an
antenna system.

It also causes people to think that separate grounds for RF, audio, and
power are somehow a good idea. And it causes people to view a connection to
earth as a cure for all ills, including, but not limited to, RFI, TVI, and
antenna performance.  And that the earth is somehow a sink into which noise
and RFI can be poured.

What REALLY matters to the RF design community is keeping track of where the
current flows, and that means ALL the current -- DC, audio, and RF
-- on every cable.  Henry Ott says this quite poetically when he speaks of
"the half of the schematic hidden behind the ground symbol."  Is the
reference PCB layer under microstrip complete, or is it broken for a extra
trace that wouldn't fit (or was forgotten) on the main layer?
Does the cable shield go directly to the shielding enclosure, or does it go
to a circuit trace to create a "Pin One Problem"  YOU may not have made
these errors, but the vast majority of equipment is built with these faults.

If you re-read my post, you will see that I wasn't objecting to the
connection of the common point of a radial system to a ground rod.

73, Jim K9YC
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