[TowerTalk] Splicing Mast

[Fred Keen]

0.125" wall is only 1/8",  I'd be a little concerned about the strength.
You may look at taking the existing 0.125 wall tube and using it for the top section by finding a 0.250 wall tube or greater on the lower section. An insert I think would be required at the joint, say 2-3' into each section. You may have to sleeve the lower section for a firmer fit at the joint.

>From your description, it doesn't IMHO appear to be all that big.
Fred KC5YN
 

    On Monday, March 19, 2018, 9:10:44 PM CDT, Shawn Donley <n3ae at comcast.net> wrote:  
 
 My instincts tell me this is a bad idea, but perhaps others have done this successfully.  I currently have an OB9-5 HF yagi (spec 7.8 ft^2 projected area) mounted one foot above the top of my tower.  The mast is 2 inch OD steel DOM with 5 ft inside the tower to the rotator and 7 ft above the tower.  Can't find the mast wall thickness at the moment but I think its 0.12 inches.  Thrust bearing is at the top of the tower.    I'm considering adding a 40M rotary dipole (3.4 ft^2) above the yagi.  But I need to place it at least 10 ft above the yagi to minimize coupling, plus I need 3 ft above the dipole for the dipole truss bracket.  That means I need 13 ft "more" mast.  Is it possible to splice an additional 13 ft of DOM onto the existing mast using a steel structural tube inserted inside the mast pieces and bolted through the masts?  If so, how long should this joint tube be?  The tower is a crank-up so I can work up there comfortably with a man lift when it's cranked down.
  


tnx for your thoughts.

N3AE
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