I'm with you, Wes. And I strongly agree with AB7E's excellent post.
The cited article does NOT say that "The Broadcast industry doesn’t seem
to put their faith in Uber grounding." It DOES say that a Ufer ground
done improperly can be a problem structurally. Notice also that the
author "is national program manager for Copper Development Association
Inc." I see nothing in the way of engineering credentials. The author
quotes extensive advice from "a power quality expert, Martin Conroy,"
again with no credentials given. That said, Conroy's advice is pretty
good, and is mostly in agreement with good engineering practice. He did
not say that the Ufer ground was a bad idea, but he did recommend
supplementing it with deep rods around the tower, spaced radially out
from the tower, and a buried ground ring, all robustly bonded together
and to the tower.
If you read the new ARRL book on Grounding and Bonding (by N0AX), you
will see a recommendation for a Ufer ground within the tower base,
bonded to the tower, and to multiple ground rods around the tower base,
spaced at least a rod length from the tower and from each other. If the
tower is close to the building, it calls for bonding between the tower
ground system and the building ground. If the tower is more than 60-100
ft from the building, bonding is NOT recommended (or useful) because
that bonding conductor (and the coax shield) have too much inductance to
be a low impedance at RF.
I was one of several engineers who Ward consulted for peer review, and
much of the book parallels my tutorial on Grounding and Bonding for ham
radio.
73, Jim K9YC
On Tue,4/18/2017 10:35 AM, Wes Stewart wrote:
I don't know whether I would call that "extensive" damage but whatever...
I have my own photos of me standing next to this anchor, but since I
can't send attachments, here is a link:
https://en.wikipedia.org/wiki/KVLY-TV_mast#/media/File:KVLYPylon.jpeg
I didn't see any extra grounding conductors. BTW, my GPS said this
was 1/4 mile from the base of the tower :-)
I'm not saying that extra grounding isn't required or is a bad idea,
just that concrete encased steel isn't a bad idea.
Wes N7WS
On 4/18/2017 8:01 AM, Rick Dettinger wrote:
Here is an article that described a Ufer ground failure that prompted
the installation of an extensive external grounding system on a 1900’
BC tower.
http://www.radioworld.com/headlines/0045/proper-grounding-and-bonding-are-crucial/338510
The Broadcast industry doesn’t seem to put their faith in Uber
grounding.
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net
This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com
