[TowerTalk] Strongest mast material?

[K7GCO@aol.com]

In a message dated 19.04.00 16:33:25 Pacific Daylight Time, w8ik@subich.com 
writes:

<< 
 Double or even triple walled mast is a waste of time and money. 
 If your mast won't handle the load, use a larger diameter 
 mast.  The strength (specifically the reduction in stress) 
 ingreased in proportion to the [outer diamer]^4.  An .125" 
 wall 2.5" OD mast is much more capable of handling a load 
 than a .5" wall 2" OD mast! 
  >>
I have no problem with larger diameter masts than needed except for the cost 
and weight.  Also it is much stronger and heavier at the top than needed.  
I've had 2nd antenna loads on telescoping masts that didn't require great 
strength like 10M beams.  Beefing up the bottom half or so worked just fine.  
I have used a 12' length of 2" x.058" wall (2' telescoped) with 6' of 1 7/8" 
inside and it took all the winds of the time.  I have heavier mast pipes now 
of 2 5/8" x1/4" wall 20' long with a variety of combinations and internal 
beef ups that have not failed me so with heavier loads after 60 years.  
Further more I used to lift by hand the telescoping pole and beam by my hands 
up in place with a sneaky way to secure and pin it.  I use a gin pole now.  I 
would not be able to lift big and heavy diameter masts by my hands.  Even 
with a gin pole I see no need for excessive weight if what I use does the 
job.  

I also use 3/4"x.028" tubing full length for my 10M tubing.  It's strong 
enough for the ends but not the middle.  So I have an internal beef up 
arrangement that gives it the proportional strength needed for the bending 
stresses that took a heavy ice loading and wind.  The main reason I did this 
was to eliminate any joints.  I have ZERO Maintenance and NO Joint Losses for 
the life of the element which no other yagi construction can claim.  

This beef up concept has been used by Leeson to strengthen elements in the 
center and end pieces to take the big winds inexpensively and without 
changing the resonant frequency of the beam.  It's really a very good system 
with many applications when properly used.  I know my needs.  I wasn't 
informed of the loads expected in the TT Post.  I keep a good eye on coast 
and weight.

One doesn't need to use preventative maintenance designs on soldered joint 
quad wires of the right size--no Penatrox either.  Those who build quads the 
right way like Antenna Mart are helping quads make a big comeback that the 
Tight Budget Mfg. ruined for years.  There have been too many UGO quad Mfgs.  
k7gco  

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