Telephone pole tower

[AG4RO]

Hello All
I have just purchased my Country home, along with it came a telephone pole with a security light that is approximately 40’ tall and I would like to mount a rotor and put a 40 meter beam up there if possible. The problem that I see is that the entire weight of the antenna and mast would be on the rotor. With this said I believe that it would be a wind and weather issues; from what I understand in a tower the antenna and mast are resting on a bearing to support the weight. How can I use the pole as a tower? Is their a commercial product for this? Any thought on how this can be done?
v/r
David
AG4RO

[K9YLI]

the weight is always supported by the rotor..
but inside a tower you have a thrust bearing to support laterl strain on the upper mast.
so build a small platform on the side ot the pole to mount the rotor and fabricate an arm above it with thrust bearing to support lateral forces.

that much lateral force on a power pole may be a lot with out some guy protection..

[KA4DPO]

My high school ham club had a telephone pole tower with a 3 element tri-band beam mounted on it. #

Our teacher had dual cross ties bolted near the top one under the other so the bolts could go all the way through the pole. #Then he fabricated a metal frame from heavy steel angle stock and mounted a thrust bearing at the apex with the rotator underneath. #The whole thing put the bearing about 5 feet above the top of the pole and gave the antenna added stability. #There wer also some angled braces that came down from the cross ties and were also bolted to the pole to add stability. This held up for years and withstood Santa Ana Winds and storms.

Good luck with the project and don't worry, the pole is stronger than most other structures.

[WA9SVD]

Mnay variables are involved. If at all possible, try to find some info on who installed the pole.

Here; the general guide is burial 4' plus 10% of the pole height, so that would be a 4' + 4' depth. but THAT is a standard for telephone/ electric service, and your pole may not comply.

There are various solutions to your "problem." One alternative (other than those already suggested) would be use of a long mast below the rotator, secured in several points to the pole, and a rotator mounted just above the top of the pole. A relatively short mast then could be used to mount the antenna to the top of the rotator. It depends upon the capacity of the rotator and the antenna used.

[ky5u]

A pole is usually just dropped in a hole and dirt packed around it. You'd have to bury alot of pole or put concrete around it to counterbalance the antenna/rotor weight + wind loading.

[N2RJ]

I am wondering if the telephone pole will even support a 40m beam.

Quote[/b] (N2RJ @ July 05 2007,07:26)]I am wondering if the telephone pole will even support a 40m beam.
that all depends on how deep pole is buried and how much concrete is used...

another option would to use guy wires just like you would with a tower...

you can make it work, it is just how bad you want it to work, and how much effort you use to make it work.....

[KA4DPO]

Companies that install telephone poles normally burry the base at about 4 to six feet. I'm sure who ever installed it wanted it to last. My guess is that the pole should be able to take 60 or 70 pounds of wind loading at a minimum.

Most multi bad beams have about 120 or more pounds of wind loading at 80 MPH. How often do you get 80 MPH winds? I would put a tribander or a quad bander on it (not a Huge one) and have fun. If the pole starts to lean you know you pushed the envelope and take it down.

This was a popular method of getting an antenna up in the air when I first got my license in the '70s. Some of them are still standing, but they have rotted and the only was to service them is to get a bucket truck to take the antenna down before cutting the pole off at the base. It is way to dangerous to climb. I have hoisted a fiberglass vhf/uhf vertical up into a pine tree at about 80 ft. and it works great. I looped the dacron rope over the top of the tree so it isn't supported by one limb. I can replace the rope at any time, so it should be good for mucho years.

[K7KBN]

Quote[/b] (K9YLI @ July 05 2007,05:46)]the weight is always supported by the rotor..
but inside a tower #you have a thrust bearing to support laterl #strain #on the upper mast.
so build a small platform on the side ot the pole to mount the rotor and #fabricate an arm above it with thrust bearing to support lateral #forces.

that much lateral force on a power pole may be a lot with out #some #guy protection..
In a "proper" thrust bearing, the bearing handles both the lateral forces AND the weight of the mast + antenna. The Rohn TB-3 is a case in point. I've used one just about forever. There is no downward force on my rotator at all.

[K9STH]

When I was with TXU (electric company for about half the State of Texas) the "rule of thumb" for wood poles was 3 feet plus 10 percent of the height.

These poles were placed directly in the ground (no concrete) and had all sorts of cross arms, etc., put on them.

Frankly, a good wood pole can withstand a good amount of lateral force without failure.

One way of putting a beam on a wood pole that has been used for decades is to use steel pipe which is installed on a hinge arrangement at the base of the pole. Then some sort of retaining mechanism is placed at the top of the pole (i.e. a "wedge shaped" notch in a metal plate).

The rotor is attached to the steel pipe so that it is located below the top of the pole and a cable with winch attached is run from near the bottom of the pole to a pulley arrangement at the retaining mechanism. The winch is used to bring the pipe, rotor, and antenna from near ground level to the operating position.

Keeping the rotor below the top of the pole where the mast above the rotor is secured in the retaining mechanism takes a lot of the lateral force off of the rotor.

In this part of the country (Texas) steel pipe that is often called "well stem" is available from various sources including salvage yards. That type of pipe is very strong and does not bend or break easily.

Glen, K9STH

[wa9cwx]

ALL good advice, BUT no one has commented on the fact that you want to put up a FORTY meter beam.

WHY?

Forty feet is not a particularly great height for a forty meter beam, and although the pole may do fine, just about ANY rotor needs SOME kind of support to handle a forty meter beam.
That is just one hell of a lot of tourque, AND lateral bending.

Even a heavily loaded forty meter beam is one heck of a lot of metal to be sitting on a non-supported mast stuck in a rotor.

AND, I am not at all sure just how well the thing will work, that close to the ground.
It WILL work, but is it all worth it, the take off angle must be very high, and the pattern may be off, too.

A Tri-Band beam, and 40/80 dipole would make a LOT more sense, IMHO.

Frank

[AG4RO]

Thank you Glen, K9STH for your idea I think that would work just fine. I have to figure out the wedge part but I think I got the idea.
v/r
David
AG4RO

[AG4RO]

Great Question why a forty meter beam?
Here is the issue, I just moved to Alton IL from Jacksonville Fl where I belong to SCAR and would like to be able to check back into the net again with some reliability. So I figured a Beam would be best. I am a little antenna crazy right now because I have finally got out from under the home owners restrictions, with two acres to work with any thought on what other antenna would give the performance of the beam antenna or near? I have looked at the Carolina Windom, Double extended Zep, and the Double Bazooka.

[wa9cwx]

From Alton to Jacksonville you do NOT need a beam on forty, BUT forty feet is the ideal (or nearly ideal I would think) height.

Any dipole will work just fine, IF you want to talk to your buddies big time, PHASE two dipoles together, strung either betweeen trees, or hung, center supported, from a support from that pole to a tree, with the dipoles hanging from it at right angles, or some other directional array made from wire.
Even a parasitic wire beam will work beyond your wildest dreams.

A few nights with the ARRL Antenna Book, a few pieces of graph paper, a loan, and you are in business. http://www.qrz.com/iB_html/non-cgi/emoticons/biggrin.gif

Frank

[wa9cwx]

The forty meter beam, at forty feet, WILL outperform a dipole, BUT although you will work DX with it, it is no where near the ideal height for a LOW angle take off needed for DX. The height you are AT, is probably optimum, most of the time, for stations in the 1000 mile range, or less.
That IS a good height, and antenna, for working regional nets, but since you only want to work the ONE net, even the beam WITHOUT the rotor, would be a more reliable, less stressed, system. But a beam is NOT needed to work into Fla, from Alton, and since it is only the one direction, IF you want a beam, or other directional antenna, USE WIRE, easy to repair, no wind stresses on poles, rotors, and no real cost.

So... MORE money for rigs, towers, antennas, towers, rigs, towers, rigs, antennas, and food for the weaker members of the family.

Frank

[W4MAJ]

Would it be necessary to check with the local utility to see if it's legal to put an antenna on the pole? They might throw a hissy fit if they found something on thier pole they didn't put there.

[wa9cwx]

No, fortunately the FCC had introduced #a bill that finally passed both the house and senate, and was signed into law last year.

It allows any licensed Amateur to install up to three antennas, (NOT to exceed 8.5 square feet), on any rural utility pole in the USA. ( Special permits, and a lowered wind resistance area, are required IN city limits).

But, if you live in the country, any antenna, up to 8.5 sq feet, is ok on any utility pole.

Frank

[AG4RO]

All great advice, I think that a wire antenna will be the way I go. I am considering a double extended ZEP cut for 80 meters, I have the room finally. Any thoughts on a wire antenna?