MASTS... a review

[KM9P at aol.com]

Well I received alot of mail on this one.

Alot of people like the chome moly masts like K5RC sells in the NCJ.  N2IC
said he had a 3 element 40 meter beam 10 feet up on one of these masts...
 The top section bent before the mast did!  Wow!  You can call K5RC for
details on pricing and shipping.  

What I'm gonna do...  Since I am only going to be putting up a Cushcraft
402CD about 10 feet up on one of the masts and a 6 element DXE 15M on the
other, I decided to go with 2" OD drawn-over-mandrel (DOM) tubing (grade
1026).  It provides a yield strength of 7000 lb/in squared.  I called around
town and found it for $6.50 per foot.  They sell it in lengths that are
anywhere from 18 to 24 feet.  I could go to the trouble of getting it
galvanized, but I'm just gonna paint it with something.  I got most of my
information on this stuff from Dave Leeson's book Yagi Antenna Design on page
7-4 & 7-6.  Dave gives you all of the formulas for calculating the
survivability of the mast in his book. 

Oh.. Charlie (K1XX) has used corner posts from chain-link fence people.  He
reinforced it inside.  It sounded like a great way to get a mast with
galvanization on it already.  But without exact numbers on it's strength I
decided to opt for the DOM stuff.

73 

Bill Fisher, KM9P
KM9P at AOL.COM


>From MSgt Bob Smith/SCSMH <smithb at GF-WAN.af.mil>  Wed Jun 22 23:37:15 1994
From: MSgt Bob Smith/SCSMH <smithb at GF-WAN.af.mil> (MSgt Bob Smith/SCSMH)
Date: Wed, 22 Jun 94 17:37:15 CDT
Subject: Tree Pole versus Antenna Covenants
Message-ID: <9406222237.AA26811 at GF-WAN.af.mil>

Can't put up an antenna?  How about a tree?  Saw this in 
Mobile Product News June 1994.

THIS IS NOT AN ENDORSEMENT!
"
Tree Poles
*Aesthetically attractive
*Nine sector antennas
*Heights up to 100 feet
	The "Tree" is an antenna support structure designed by
ARCNET Inc and fabricated by Valmount Industries, a monopole 
manufacturer.  The bark and foliage have been developed and tested
by The Larson Company who create weather artificial landscapes, 
habitates and environments.  This antenna alternative is designed
for the cell site where aesthetics are a primary objective.  The 
Tree is a White Pine, a variety that is common throughout the 
continental United States.  Other species are available.  The
Tree has been tested for transmission clarity as well as weathering.
A palm tree version currently is being developed.

VALMOUNT INDUSTRIES, INC.  PO BOX 358, VALLEY, NE  68064-0358
"

	"aesthetically pleasing"  sounds like just the right
jargon for planned communities with antenna restrictions.  Could
two be set up in a phased array?

73 de Bob ND1H
smithb at gf-wan.af.mil

*****************THIS IS NOT AN ENDORSEMENT****************

>From Steve Merchant <merchant at crl.com>  Thu Jun 23 00:24:44 1994
From: Steve Merchant <merchant at crl.com> (Steve Merchant)
Date: Wed, 22 Jun 1994 16:24:44 -0700 (PDT)
Subject: Mast question
Message-ID: <Pine.3.87.9406221644.A20847-0100000 at crl.crl.com>



On Wed, 22 Jun 1994, Trey Garlough wrote:

> > I have purchased a 20' mast from Texas Towers.  It has withstood my 
> > requirements for 7 years now.  It came galvanized.
> 
> Yep.  Same here, but as I recall the mast I got from Texas Towers was
> 2" before being galvanized, so don't plan to use a Rohn 2" thrust bearing
> with it.

I had the same experience.  Took my Rohn thrust bearing to a machine shop 
and had it "enlarged" to fit the new 2++" od mast.  Worked fine, cost about
$10 as I recall.

Steve - N4TQO/6
merchant at crl.com


>From Randy A Thompson <K5ZD at world.std.com>  Thu Jun 23 03:29:42 1994
From: Randy A Thompson <K5ZD at world.std.com> (Randy A Thompson)
Date: Wed, 22 Jun 1994 22:29:42 -0400 (EDT)
Subject: Masts, More Questions
Message-ID: <Pine.3.89.9406222244.A18183-0100000 at world.std.com>

Method 1 - The simply easy way

Make sure the mast is inside the tower before you put it up!  Then you 
only have to lift straight up and the mast is never leaning precariously 
above your head!

Method 2 - Get a crane

This works great and makes antenna work a lot of fun.  Have them put the 
antennas up while you are at it.  After all, you already paid for the 4 
hour minimum.

Method 3 - Last resort

Ignore method 1 suggestion.  Ask yourself if you feel lucky.  Then go for 
it!  Once the mast is inside the tower, the antennas are cake.

Seriously, you might want to pull the mast up without having the top 
section on the tower.  Gives you a little bigger hole to drop it into 
(the inside of the tower) and a bit more margin for error.

Good luck!

Randy
k5zd at world.std.com


On Wed, 22 Jun 1994, Doug Snowden wrote:

> Ok, now we have a good idea of what people are using, or recommend
> for use as mast material. Now, what is the typical scenario in
> getting the mast to the top of the tower, installed, with antennas?
> I think we are talking about over 300 lbs (???) of mast if we were
> using 3 inch stuff of 20 foot length. My main concern is the
> manipulation of the mast while it is on/in the tower and antennas 
> are being added.  You can guess that I have never had more than one
> antenna on my mast, and never had a big mast.
> 
> Doug, N4IJ drs at ccd.harris.com
>