On Sun, 25 Sep 2011 20:28:15 -0500, dave wrote:

I'm not sure I'd want to hang a TVRO dish on one. Have you ever been on
the upper levels inside the Post Office building on Mt. Wilson?

http://www.cellsiteanalysis.net/cell_site_analysis_images/Cell_Site_Mast_Loaded.jpg
(It's not Mt Wilson. It's in Turin Italy).

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On 9/25/2011 9:06 PM, Jeff Liebermann wrote:
On Sun, 25 Sep 2011 18:46:17 -0500, Jeffrey
wrote:

Each cross brace has about a dozen 2" diameter galvanized stubs to
attach the antennas to. They are bolted directly to the cross braces.

All the wood was treated with Creosote just like the poles themselves.
The site was at least 40 years old the last time I was up there in 2005.

You mean like this?
http://802.11junk.com/jeffl/pics/Old%20Repeaters/slides/LoopMtn02.html
http://802.11junk.com/jeffl/pics/Old%20Repeaters/slides/LoopMtn03.html
We had similar derrangements at 3-4 other sites. Telephone poles and
lumber were about 20% of the cost of a galvanized steel tower.

Been on Loop Mountain too. And Oat, Lukens and Mt. Wilson.
The "tower" I was referring to specifically though was Hollywood
Hills.

Lightning protection was at the entry point to the building with a
metal plate with some PolyPhasor feed through protectors. The end and
highest antennas were also grounded with a undersized #4 copper wire
running down the pole to a ground rod at the base. We didn't get any
lightning hits because there was an all metal forestry lookout at the
highest point on Santiago which took all the hits.

The grounding inside and outside the building was your typical "Amateur"
installation. 3/4" water pipe with 90 degree elbows soldered together.

Our real protection was the water tank owned by the DWP slightly up
the hill from us. Similar to ranger tower protecting Santiago.

The stubs didn't look any worse than the usual stubs bolted to metal
tower assemblies.

We used the same hardware that was used the Ma Bell. Thick galvanized
and loose fitting steel hardware. Same as what the typical steel
tower is made from these days. It works nicely on both metal and
telephone poles.

Yup. Works moderately well until you get some clown in the building
that runs an 8-way receive antenna and 8 bandit taxi cab repeaters.

Jeff

--
"Everything from Crackers to Coffins"

On 9/25/2011 8:28 PM, dave wrote:
I'm not sure I'd want to hang a TVRO dish on one. Have you ever been on
the upper levels inside the Post Office building on Mt. Wilson?

As the other Jeff pointed out, there's reasons to NOT use wood,
but it's not because wood is bad. Purely a dimensional change
problem.

Although, I suspect that the original poster is thinking of
strapping a 2x4 across two legs of the tower and using just enough
"arm" to get the dish to clear the tower. It may work, and it may
be a nightmare trying to accurately align it.

Jeff


--
"Everything from Crackers to Coffins"

On Sun, 25 Sep 2011 22:11:11 -0500, Jeffrey Angus
wrote:

http://802.11junk.com/jeffl/pics/Old%20Repeaters/slides/LoopMtn02.html
http://802.11junk.com/jeffl/pics/Old%20Repeaters/slides/LoopMtn03.html

Been on Loop Mountain too. And Oat, Lukens and Mt. Wilson.
The "tower" I was referring to specifically though was Hollywood
Hills.

There were plenty of telephone pole antenna "towers" in the Hollywood
Hills during the 1960's and 70's. Most are probably still there. A
steel tower required an elaborate ordeal process compliments of the
planning department. Telephone poles were deemed to be something akin
to a tree, and were easier to permit.

During the 1960's, Ken Sessions (SK) had a GE outdoor box mounted on
top of a telephone pole just below Loop Mountain. His problem wasn't
lightning hits. It was hits from .22, .38, and larger. He reinforced
the inside of the box with armor plate, which worked until someone
used AP ammunition. We offered him cheap space in Gene Clothier's
site on Loop, but Ken refused for some unknown reason.

The grounding inside and outside the building was your typical "Amateur"
installation. 3/4" water pipe with 90 degree elbows soldered together.

Lousy cross sectional area. Hopefully, they left one end open. If
the copper pipe were sealed at both ends, and it took a lightning hit,
the air inside would get rapidly very hot and probably turn the pipe
into a fragmentation bomb. If they really want to blow out the wall,
fill it with water.

Our real protection was the water tank owned by the DWP slightly up
the hill from us. Similar to ranger tower protecting Santiago.

Bowmont water tank, off Mullholland between Laurel and Coldwater
Canyons?


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On 9/25/2011 10:53 PM, Jeff Liebermann wrote:
On Sun, 25 Sep 2011 Jeffrey wrote:
The grounding inside and outside the building was your typical "Amateur"
installation. 3/4" water pipe with 90 degree elbows soldered together.

Lousy cross sectional area. Hopefully, they left one end open. If
the copper pipe were sealed at both ends, and it took a lightning hit,
the air inside would get rapidly very hot and probably turn the pipe
into a fragmentation bomb. If they really want to blow out the wall,
fill it with water.

Of course the end wasn't open. And there was a pair of Tee's in
the middle so it could zig zag across the ceiling. There was a
second ground pipe running around the outside of the building.

Other sites had a decent ground using #4 solid copper wire and
exothermic connectors. This, obviously, was not one of them.

Our real protection was the water tank owned by the DWP slightly up
the hill from us. Similar to ranger tower protecting Santiago.

Bowmont water tank, off Mullholland between Laurel and Coldwater
Canyons?

I don't think so. This one was off of Cyprean Dr. Via Hollywood Blvd.
http://g.co/maps/dw5py 2050 CYPREAN DR. LOS ANGELES, CA

If that link works properly, you can see a nice clear picture of the
antenna rack.

Jeff-1.0

--
"Everything from Crackers to Coffins"

On Sun, 25 Sep 2011 20:53:24 -0700, Jeff Liebermann wrote:

On Sun, 25 Sep 2011 22:11:11 -0500, Jeffrey Angus
wrote:

http://802.11junk.com/jeffl/pics/Old...eaters/slides/
LoopMtn02.html
http://802.11junk.com/jeffl/pics/Old...eaters/slides/
LoopMtn03.html

Been on Loop Mountain too. And Oat, Lukens and Mt. Wilson. The "tower" I
was referring to specifically though was Hollywood Hills.

There were plenty of telephone pole antenna "towers" in the Hollywood
Hills during the 1960's and 70's. Most are probably still there. A
steel tower required an elaborate ordeal process compliments of the
planning department. Telephone poles were deemed to be something akin
to a tree, and were easier to permit.

During the 1960's, Ken Sessions (SK) had a GE outdoor box mounted on top
of a telephone pole just below Loop Mountain. His problem wasn't
lightning hits. It was hits from .22, .38, and larger. He reinforced
the inside of the box with armor plate, which worked until someone used
AP ammunition. We offered him cheap space in Gene Clothier's site on
Loop, but Ken refused for some unknown reason.

The grounding inside and outside the building was your typical "Amateur"
installation. 3/4" water pipe with 90 degree elbows soldered together.

Lousy cross sectional area. Hopefully, they left one end open. If the
copper pipe were sealed at both ends, and it took a lightning hit, the
air inside would get rapidly very hot and probably turn the pipe into a
fragmentation bomb. If they really want to blow out the wall, fill it
with water.

Our real protection was the water tank owned by the DWP slightly up the
hill from us. Similar to ranger tower protecting Santiago.

Bowmont water tank, off Mullholland between Laurel and Coldwater
Canyons?

K-Joy site? You must know Western Technical Services if you used to play
in Orange County. They build steel towers. If you order a mesh dish they
send an unmarked vehicle.

On Mon, 26 Sep 2011 07:59:44 -0500, dave wrote:

K-Joy site? You must know Western Technical Services if you used to play
in Orange County. They build steel towers. If you order a mesh dish they
send an unmarked vehicle.

Never heard of them, but that was 40 years ago. We did our own
antennas all of which were on wood poles. Same with everyone else on
Santiago Pk in the late 1960's. Even the Air Force building used
multiple short telephone poles, with one antenna per pole, a really
bad idea. I worked for PMC (Pacific Mobile Comm) in Stanton CA at the
time.
http://11junk.com/jeffl/pics/Old%20Repeaters/slides/PMC02.html

Why would they send an unmarked vehicle to install a mesh dish?

I think (not sure) that I found a recent (4/2009) photo of the PMC
building on Santiago:
http://images.summitpost.org/original/503620.jpg
Note the large number of wooden poles and outriggers that are still in
use. I was going to mumble something like "nobody mounts dishes on
wood poles", but it seems that there are two in the photo. Sigh. The
wood structure looks much the same as it did 40 years ago minus the
wall of far too closely spaced, intermod generating, antennas.

Recent structures are all steel.
http://images.summitpost.org/original/503619.jpg


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On 9/25/2011 7:06 PM, Jeff Liebermann wrote:
The end and
highest antennas were also grounded with a undersized #4 copper wire
running down the pole to a ground rod at the base. We didn't get any
lightning hits because there was an all metal forestry lookout at the
highest point on Santiago which took all the hits.


#4 is plenty big enough for lightning grounding. The current is high,
but the duration is short. You see larger lightning conductors for
mechanical reasons (e.g. where it might get damaged, or where it has to
move repeatedly).

On Mon, 26 Sep 2011 12:04:21 -0700, Jim Lux
wrote:

On 9/25/2011 7:06 PM, Jeff Liebermann wrote:
The end and
highest antennas were also grounded with a undersized #4 copper wire
running down the pole to a ground rod at the base. We didn't get any
lightning hits because there was an all metal forestry lookout at the
highest point on Santiago which took all the hits.

#4 is plenty big enough for lightning grounding. The current is high,
but the duration is short. You see larger lightning conductors for
mechanical reasons (e.g. where it might get damaged, or where it has to
move repeatedly).

One of the neighboring towers took a direct hit. The #6 AWG he was
using literally exploded, spraying melted copper everywhere and
blowing pieces of concrete block all over the building.

http://en.wikipedia.org/wiki/American_wire_gauge#Table_of_AWG_wire_sizes
Fusing current (32msec) for #4 is 34,000 Amps. The average lightning
hit is about 20,000A but can go up to 200,000A.
http://www.lightningsafety.com/nlsi_info/media.html
Other references offer averages from 5,000 to 50,000A. I would call
#4 marginal but probably adequate for California, which doesn't get
much lightning.

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com
# http://www.LearnByDestroying.com AE6KS

"Jeff Liebermann" wrote in message
...

snip


Well, if you're going to go through all that trouble to install a
proper ground, you can do as well using Unistrut instead of a 2x4.
http://www.unistrut.us

Unistrut is wonderful. About 20 years ago, I used to engineer installations
in a big government lab in San Diego and it was the customer's preferred
method for anything structural that didn't involve concrete. :-)

I learned you could do anything with Unistrut. It's the Erector Set / Lego
Blocks for grown-up kids.

"Sal"