I think three feet or so would do. I have a Rohn 45 with a tapered top section
w/thrust bearing. I put the rotor down three rungs (~4') and use a 10' 1/4"
wall DOM steel mast.
I bought the mast material from Industrial Metal Supply which operates in the
SW. You probably have something similar in your area. They have no heartburn
about cutting to length.
Wes N7WS
On 4/17/2017 1:54 PM, Clifton Keely via TowerTalk wrote:
I am in the process of erecting a Rohn 25G to 30 feet with a house bracket. My question is
how long should the mast be within the tower? I have a thrust bearing top plate and a good
rotor for the load, but should the mast extend 2 feet below the top plate or 6 or 8 or 12
feet. Would there be a real advantage to letting the mast go below the next tower joint down
(10 ft). DX sells a high budget mast they they won’t cut, it is 22 feet long. I
don’t think I want to have a mid sized triband 10 or 12 feet above the top
plate/thrust bearing. My plan is to place the antenna at about 5 feet above the top
plate/bearing Speak to me someone who knows. Please. All advice greatly appreciated. Clif
AA6FE.
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