Antenna Mast Length

[edfiero]

I'm thinking of putting up a 3 element beam on a Rohn 25 type tower.

What is the rule of thumb for how much of the mast pole should stick out of the top of the tower? Should it be kept as short as possible, or is there any problem with having the pole 10ft+ above the top of the tower? I really need another 10 feet to have the antenna fully clear the peak of my roof, and I'd rather not buy another tower section, if I can get the extra height directly from the mast pole.

Also any suggestions on mast pole material. I was hoping to get something that was 1.5" OD, however it seems most poles are only 1.25" OD

 

[SIX-SHOOTER]

I'm thinking of putting up a 3 element beam on a Rohn 25 type tower.

What is the rule of thumb for how much of the mast pole should stick out of the top of the tower? Should it be kept as short as possible, or is there any problem with having the pole 10ft+ above the top of the tower? I really need another 10 feet to have the antenna fully clear the peak of my roof, and I'd rather not buy another tower section, if I can get the extra height directly from the mast pole.

Also any suggestions on mast pole material. I was hoping to get something that was 1.5" OD, however it seems most poles are only 1.25" OD

The mast should be long enough so that the elements of a beam clear the top of the tower & there is no set distance for a vertical.You may have as much mast pipe as you think will survive the weather conditions in your area.I have seen them with as much as 30 ft of mast & I have 11 feet myself out the top of the 50' of ROHN 25 in my back yard. I have (4) Yagi antennas on it & it has survived many Hurricanes,Tropical Storms,& North Florida Thunder Storms in the 18 years it has been up.Height is Might.I have 1 1/2" Schedule 40 pump pipe as my mast.

SIX-SHOOTER