40' ENT Pipe Mast for Antenna?

[K239]

40' EMT Pipe Mast for Antenna?

Howdy,

I have a need for a tower for our antenna for a repeater for our 450Mhz equipment. We have a 50' box trailer that we use as our mobile garage more or less when we're out in the field.

Essentially, I need to build a collapsible tower we can stow when not needed, and deploy when necessary and mount our repeater antenna on top.

I wanted to purchase 3 15' sections of EMT pipe, 1", 1 1/2" and 2" pipe sections, essentially have them overlap, and bolt together with a couple bolts and nuts, and slip into a 2 1/2 " pipe that's about 5 feet in length, with bolting the base section which is mounted to a corner of the trailer in three or four places, and bolting the pipe section to the base in 3 places to keep it standing.

Ive never done this before so I want to ask....

would this work....

 

[radionut44]

ENT is nonmetallic likely will bend when heated by sun. Did you mean EMT, othwise known as thinwall conduit which is metallic?

 

[K239]

ENT is nonmetallic likely will bend when heated by sun. Did you mean EMT, othwise known as thinwall conduit which is metallic?

That's correct, I'm sorry.

 

[prcguy]

The EMT conduit does not come in sizes that fit inside each other very well, so your mast will wobble some due to the spacing between the sizes. I would not use that to hold up anything but a very small and lightweight antenna.

I have a medium size antenna up now using two 10ft EMT sections that overlap about 2ft and I would not go any higher or put a larger antenna on that.

Why not get a 40ft telescoping pushup mast? They are a little stronger but still not designed to be all the way up without guying.
prcguy

 

[K239]

The actual antenna is only about two or three feet and only weighs 10-15lbs at most.

 

[mmckenna]

You'll want something with a thicker wall than EMT conduit. While you may be able to get it to work, if it's not guyed, a strong breeze is going to bring it down.
Thick wall conduit (EMC) might be a better choice, but it's going to be heavy. You'd at least be able to use threaded couplers between sections, but I wouldn't be too confident in those, as they are not designed for those sorts of forces.

40 feet would really be begging for something guyed. As mentioned above by PRCGUY, take a look at the guyed push up masts. You'd probably be able to mount it directly to the trailer, but you'd need to climb on top to do the push up part. If you can, rig up either a tilt over mount, or be able to remove it completely.

Can I ask how you came to the conclusion you need it 40 feet high?

There are ways of doing this, really depends on your budget. There are some military mast systems that you can find surplus that might be a good option. I've seen tilt over masts done on RV's and command vehicle type installs. Pneumatic telescopic mast would be a good choice, but would be expensive.

 

[K239]

You'll want something with a thicker wall than EMT conduit. While you may be able to get it to work, if it's not guyed, a strong breeze is going to bring it down.
Thick wall conduit (EMC) might be a better choice, but it's going to be heavy. You'd at least be able to use threaded couplers between sections, but I wouldn't be too confident in those, as they are not designed for those sorts of forces.

40 feet would really be begging for something guyed. As mentioned above by PRCGUY, take a look at the guyed push up masts. You'd probably be able to mount it directly to the trailer, but you'd need to climb on top to do the push up part. If you can, rig up either a tilt over mount, or be able to remove it completely.

Can I ask how you came to the conclusion you need it 40 feet high?

There are ways of doing this, really depends on your budget. There are some military mast systems that you can find surplus that might be a good option. I've seen tilt over masts done on RV's and command vehicle type installs. Pneumatic telescopic mast would be a good choice, but would be expensive.

For feet from ground level would provide sufficient direct line of sight in all directions.

We normally try to find the tallest building in the area we can and mount the antenna on a tripod on there. But we found in the middle of the woods and swamp, Where some of our more recent wide-area searches have been, our teams get quite the distance from the Command Post and are unable to effectively communicate back to us or us to them.

By moving our repeater up and over any obstacles, and in-between our command post and search teams, it would allow us to provide a bit better communication stability. At least that's what i envision.

I'm open to any suggestion or feedback. That's why I'm coming here first.

 

[mmckenna]

OK, makes sense. Just looking for the background here.

Ideally mounted off the trailer would give you a stable base, but keeping it portable would be preferred?

I'd recommend looking at the military surplus antenna mast systems. They are designed to be portable and provide a decent temporary set up.

Here's a few other ideas:
EasyUp EZ32B Mast Ground Mount Stake Plate Antenna Heavy Duty Galvanized Steel Base Universal Telescopic

W6CAW

Either way you are going to need some sort of portable mast. 40 feet high is going to require guy ropes/wires to keep it in place. You'll have a hard time making something self supporting AND portable.

The Mast Company - Product Overview

Welcome to MilitaryPoles.com I offer Military Pole Kits for Ham Antenna Mast / Flags / Hammock Stands / Emergency Preparedness. I also offer Tripods and Guy Rings that we build made for these Aluminum poles.

AB-86/GRA-4

There are some lighter weight fiberglass push up masts that would probably work just fine with a small antenna on top.

This coupled with a good base and guy ropes would probably be a good system and still be portable:
Heavy duty fiberglass push-up masts with convenient thumb clamps!

 

[prcguy]

I have a couple of the AB-86/GRA-4 mast kits and they are probably the best of the bunch. I use one all the time on a parked vehicle with the mast in a trailer hitch mount and the tallest I can possibly go is 25ft without guying it. These were designed to be fully assembled on the ground with guy ropes attached, then walked up to about 40ft by a crew of people. Even with two people handling the mast 25ft is the max height unguyed without things getting out of hand.

If you get a 40ft telescopic "push up" mast you can attach it to something then push all the sections straight up with your antenna by one person. The key to this working is having it attached to a stable platform that grabs the base and top of the first section like your 50ft box trailer.

Here is an ideal solution but a bit pricy, these come in sizes up to 52ft and this one is 42ft tall. The Will-Burt mast is designed to be completely unguyed and if you look at the construction you will see why the other masts were never designed to be free standing. You will also see why the Will-Burt masts cost upwards of $16k new but they can be found used in good shape for a couple thousand $$.

http://forums.radioreference.com/pi...tup/307713-prcguys-little-mobile-antenna.html

The OP mentioned his repeater antenna is only 2 or 3ft tall which would be a low gain little whimpy thing. You could replace that antenna with a high gain version that is more appropriate for repeater use and at 20ft high it would really extend your range.
prcguy

OK, makes sense. Just looking for the background here.

Ideally mounted off the trailer would give you a stable base, but keeping it portable would be preferred?

I'd recommend looking at the military surplus antenna mast systems. They are designed to be portable and provide a decent temporary set up.

Here's a few other ideas:
EasyUp EZ32B Mast Ground Mount Stake Plate Antenna Heavy Duty Galvanized Steel Base Universal Telescopic

W6CAW

Either way you are going to need some sort of portable mast. 40 feet high is going to require guy ropes/wires to keep it in place. You'll have a hard time making something self supporting AND portable.

The Mast Company - Product Overview

Welcome to MilitaryPoles.com I offer Military Pole Kits for Ham Antenna Mast / Flags / Hammock Stands / Emergency Preparedness. I also offer Tripods and Guy Rings that we build made for these Aluminum poles.

AB-86/GRA-4

There are some lighter weight fiberglass push up masts that would probably work just fine with a small antenna on top.

This coupled with a good base and guy ropes would probably be a good system and still be portable:
Heavy duty fiberglass push-up masts with convenient thumb clamps!

 

[K5MPH]

Im with the rest of the guys go with the 40 foot push up pole i use two of these and they work fine also make sure they have guide line rings.....