[TowerTalk] Source for 2" OD Mast

[Jim Thomson]

Date: Fri, 4 Jan 2013 12:26:14 -0800
From: Jerry Gardner <jerryw6uv at gmail.com>
To: towertalk at contesting.com
Subject: [TowerTalk] Source for 2" OD Mast

Anyone know of a source for a 2" OD 5 to 20 foot steel mast in the
vicinity of the S.F. Bay Area? Something with around 87 k psi yield
strength would be ideal.

Lots of on-line places sell these, but the shipping cost is greater than
the cost of the mast itself. If there's someplace close to me that stocks
something suitable, I'll rent a U-Haul truck and go pick it up.

73, Jerry

##  which is it you actually want,  a 5’ mast.... or a 20’ mast ??? 
If you are only going to put the yagi 1’ above the top of the tower
even sched 40/80 water pipe will work just fine.   BTW, 1.5”  water pipe
has an OD of 1.9”. It’s  1.9” OD whether you buy sched 40, (.145” thick)
or sched 80, (.200” thick). 

##  1026 DOM is typ 87-90 ksi. 
UN heat treated 4130 chromolly is 70 ksi.  Heat treated, it ranges from
104 ksi up to 120 ksi. 

## 2”  OD  x .375” thick chromoly weighs 7 lbs per foot.   And 2.875 x .25” thick
1026 DOM also weighs 7 lbs  per foot.  The 2.875”  dom mast is a helluva lot stronger.

##  use the FREE arrl mast software to do the math calcs  for you. 
Plane jane water pipe is aprx 35 ksi. 

##  Rohn TB-3 bearing has an ID of 2 1/16.    A TB-4 has a ID of 3  1/16” 

##  4140 is TOOL steel. 

##  heat treated chromolly takes place at aprx 1100 deg F.   Galvanizing it takes
place at 900F....and will NOT affect the heat treating  per jay at array solutions..who has
see the procedure done in ohio.  

##  You can also buy 4130 chromolly masts  from UST in california. 
##  a fellow here in town had a 4 el quad on a 30’ x 3”  boom, aprx 9’  above the top of his
rohn 25 tower. He used galvanized 1.9” OD x .145” wall  water pipe... 35 ksi  ( sched 40).
It bent badly  in a 65 mph gust one day.   What a bitch to get the quad + bent mast down. 

##  so how high is your yagi/s going to be above the top of the tower ??   The free arrl mast calculator
will tell u in a few minutes exactly what mast is required for a given peak wind gust.  

later... Jim  VE7RF