[baumgrenze]

Is there an ideal elevation angle for antenna mast guy wires? The angle I am talking about is the angle between the "top" of the mast and the wire.


I have a flat roofed home. Its nice for erecting antennas, sometimes a problem when it rains.


I'm close enough to the stations I want to receive so that 2' above the roof works.


I want to relocate an full sized FM antenna on a mast just tall enough to safely walk under the antenna, say 78" . I also want to install a second mast which will carry a 9# rotor and a 2.5# UHF antenna. This is probably a lighter load in a wind than the FM antenna. I want to minimize the space covered by guys; they are a hazard on the roof, too. I'll be reroofing as I do this, so I plan to install pipe flanges and 1.25" pipe as anchors before the new membrane is installed. I want to know where to plan to put them.


Thanks.


baumgrenze

 

[Colm]

Ideal guy wire angle is 45 degrees according to old Channel Master installation guide. Anything 10' or more above the mount should be guyed. In your case, you might consider using tripod mounts with a 8' or so mast and eliminate the guy wires. You can make the whole thing more rigid by using larger diameter mast.

 

[johnpost]

the suggestion of a 8' tripod is a good idea, or a 5' or 6'. you can make a wood base, spreads the tripod load to not damage roof, and anchor to roof.


put a tall mast into the tripod (quadpod) put FM on that a foot or two below the top. put rotor on top and short mast for UHF antenna. if you want FM antenna fixed.

 

[Colm]

And if you are going with only a single section of mast, you might as well use EMT from your local home improvement store at about half the price for "antenna mast". It is approximately the same gauge, galvanized, available everywhere in a variety of diameters, and you don't need the reduced diameter end to stack another piece on anyway. The brightness will go away with some weathering, or you can paint it whatever color makes it disappear in your background. 1" trade diameter should be fine for your needs, or go for 1 1/4".

 

[iowegian3]

I'd think about a non-penetrating roof mount such as these sold at Solid Signal. Then on second thought, while composing, these would be a good solution for existing membrane roofs. If your roofer is OK sealing around your mast when installing the new membrane, I'd continue with your plan. It'd be no different than working around a vent pipe.


But if you have to guy, then you've got three more holes in the membrane to work around. So on third thought I'd say to stay with non-penetrating roof mounts.

 

[baumgrenze]

Thanks for all the insights.


The house is post&beam. I plan to mount the FM antenna on a steel plate lag bolted to the side of a 4x14 beam. I'll bring it out with a section of 2" square box beam to clear the roof's gravel stop/fascia board. On this I'll mount a section of stainless pipe large enough to accommodate the mast.


The TV antenna and rotor I plan to mount using some 6x6 pieces of 1/4" angle iron I have. The roof has 2 levels. I'll bolt the angle to the underside of the 2x6 decking under the membrane and use it to come around the 2x4 gravel-stop/ fascia board into which I will also drive deck screws. The vertical face of the angle iron will carry a section of stainless pipe which will serve as the anchor cup for the mast.


I'm mostly just concerned about guying the mast against winter winds. When I bought the house 35 years ago, the previous owner had mounted a 10' mast carrying a Cornell-Dubilier Ar-22R rotor which in turn carried a second 10' mast with the FM antenna, a large VHF antenna, and a UHF antenna. It seemed securely guyed, but it bent in half in a winter rainstorm not long after I bought the house. The lowest antenna just missed penetrating the roof membrane. I live on the San Francisco Peninsula in Palo Alto. My predecessor was excited about getting blacked out football games from Sacramento.


Thanks,


baumgrenze

 

[johnpost]



Quote:
Originally Posted by baumgrenze /forum/post/16973186


I'm mostly just concerned about guying the mast against winter winds. When I bought the house 35 years ago, the previous owner had mounted a 10' mast carrying a Cornell-Dubilier Ar-22R rotor which in turn carried a second 10' mast with the FM antenna, a large VHF antenna, and a UHF antenna. It seemed securely guyed, but it bent in half in a winter rainstorm not long after I bought the house. The lowest antenna just missed penetrating the roof membrane. I live on the San Francisco Peninsula in Palo Alto. My predecessor was excited about getting blacked out football games from Sacramento.


Thanks,


baumgrenze

masts and towers should be guyed in 10 foot increments going up and at the top. not a bad idea to also guy at the rotor no matter where it is.


if something folds in half it either wasn't guyed enough or maintained enough.