[TowerTalk] One thrust bearing vs. two

[Tod -ID]

Good Idea>
 
 
I am planning to install an XM-240 ten feet above a Force 12 C-31XR on a 20 foot
0.25" wall 1026 DOM mast. Sixteen feet of the mast will be above the top of the
tower.
 
Tod, K0TO
 


  _____  

From: N7KA at comcast.net [mailto:N7KA at comcast.net] 
Sent: Tuesday, August 11, 2009 10:52 PM
To: Tod -ID
Subject: Re: [TowerTalk] One thrust bearing vs. two



A lot has to do with mast length above tower and antenna load.  The lower thrust
bearing is mostly used to take the lateral thrust load presented by a long mast.
I use 2 since my 21 ft mast is 15ft out the top of tower and 6 feet inside top
section.  Not a single problem in 22 years.

 

However if a short mast 2 thrust bearigs is not really needed.  In fact I used
Rohen 25G tube top for years with NO thrust bearings, and that with several
yagis 20/15M, or 20/40M.

 

For best advice detail what you plan to do.  General questions will get a mixed
bag of answers.

 

Arne N7KA