douglasaz
Member
I am going to build a 18 foot mast for uhf/vhf antennas and I was thinking either pvc or chainlink top rail pipe. What would work better.
18 foot mast
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Chainlink...PVC is just not strong enough!!!!!
mmckenna
I ♥ Ø
Given the choice between only those two? Top rail pipe.
PVC is too flexible and won't last long. Long term exposure to ultra violet light, especially all the sun you get there in Arizona, is going to be a problem. Even if you went with one of the heavy schedule pipes, it's still not going to be stiff enough.
Not sure if top rail will stand up to a lot of wind loading, but given the choice between only those two, it'll be your better choice.
Just make sure you properly ground it. A big metal pipe sticking up in the air is going to be a lightning magnet.
PVC is too flexible and won't last long. Long term exposure to ultra violet light, especially all the sun you get there in Arizona, is going to be a problem. Even if you went with one of the heavy schedule pipes, it's still not going to be stiff enough.
Not sure if top rail will stand up to a lot of wind loading, but given the choice between only those two, it'll be your better choice.
Just make sure you properly ground it. A big metal pipe sticking up in the air is going to be a lightning magnet.
douglasaz
Member
The lightning is what i was thinking about with the top rail, plus, i can't seem to find a lop of top caps for them.
Painting would help with the pvc, but would only delay weathering.
Painting would help with the pvc, but would only delay weathering.
On the side
I agree with those who say go with the metal pipe.
But since you said antennas, as in you're thinking more than one, one advantage to PVC is that you could mount verticals on the side of the mast, and not worry too much about radiation pattern distortion.
I agree with those who say go with the metal pipe.
But since you said antennas, as in you're thinking more than one, one advantage to PVC is that you could mount verticals on the side of the mast, and not worry too much about radiation pattern distortion.
mmckenna
I ♥ Ø
PVC won't solve the lightning issue. You'll still have antennas on it with cables running to your radios. PVC mast or not, you need to address direct lightning strikes as well as induced current from nearby strikes.
Find a plastic PVC cap that will fit over the top. If it's not a tight fit, some silicone sealant will hold it in place.
Painting PVC will work for a while, but as it flexes, the paint won't. It'll start coming off pretty quick. You could try electrical PVC conduit. I'm pretty sure it's got UV stabilizers in it, it's dark grey, but it's still going to flex a whole bunch.
Eng3ineer
Member
I used 1-3/8" top rail pipe for my mast you can see it in my shack photo's. For mine I used a 21 footer plus a 10 footer. Word of warning make sure you don't go to high without braces. I had way too much not supported above my roof line and it ended up bending over when good thunderstorm with high winds passed through.
Also check with your local fence companies first as they have longer lengths 21 foot vs box stores lowes, home depot only had 10 footers in stock but could order the 21 foot top rail. For a cap used a 1-1/4 pvc cap. I heated it up with torch then hammered it on with rubber mallet.
Also check with your local fence companies first as they have longer lengths 21 foot vs box stores lowes, home depot only had 10 footers in stock but could order the 21 foot top rail. For a cap used a 1-1/4 pvc cap. I heated it up with torch then hammered it on with rubber mallet.
I bought the military 4' sections from ebay. They use them for holding up camouflage.
I have an old patio pole in a concrete footing that is used as a pool gate today. It was cut about 4.5' above deck height. Then I used a thick walled galvanized pipe about 4' long as an intermediate pipe that the 2" military sections would fit into. So far I have 3 sections of aluminum on top of the steel; so I'm up about 18'. Recently, L.A. had winds up to 70 mph (we get these seasonally). I just sat the Serio 21' 5/8 wave ground plane up there and let it fly in the wind. I have yet to add the radials as I was testing the wind stuff. It flung around like a bull whip, but never fell over or broke. Now I just have to intert another 2 four foot sections for as height of 26' to the base of the antenna... and oh yeah! Put on the guy wires!; there's noting up there yet. So that's my input. The 4' military poles are great, sturdy antenna poles. Shippable and storeable in the garage.
I have an old patio pole in a concrete footing that is used as a pool gate today. It was cut about 4.5' above deck height. Then I used a thick walled galvanized pipe about 4' long as an intermediate pipe that the 2" military sections would fit into. So far I have 3 sections of aluminum on top of the steel; so I'm up about 18'. Recently, L.A. had winds up to 70 mph (we get these seasonally). I just sat the Serio 21' 5/8 wave ground plane up there and let it fly in the wind. I have yet to add the radials as I was testing the wind stuff. It flung around like a bull whip, but never fell over or broke. Now I just have to intert another 2 four foot sections for as height of 26' to the base of the antenna... and oh yeah! Put on the guy wires!; there's noting up there yet. So that's my input. The 4' military poles are great, sturdy antenna poles. Shippable and storeable in the garage.
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