Antenna tower hinge

If you were to look at a commercially-made pivoting base for typical light duty triangle-type tower (essentially conduit and zigzagged steel rod) you'll see that the anchoring points need to be very heavy duty.

Slight wind loads at the top of a 25 foot tower can generate a lot of stress at the base.

A base I saw at a local dealer was made with parts fabricated from 1/2" steel.. 2 "legs" pivot, and one separates with a heavy duty latching mechanism.

You will most likely need to take the tower apart/down (top first) to install a proper pivoting base.

If the tower were oriented properly (one triangle point toward the wall), a winch could be installed in the garage for lowering the tower away from the wall.

You might be further ahead to rent or hire a bucket truck for an hour to allow you to get up there to change the antenna more easily, and be done with it.

Thanks for taking the time and effort to type all that, which I saved. I've helped other hams work on radio antennas, and learned the Army's version of field rigging.

jsw

Thanks for taking the time and effort to type all that, which I saved. I've helped other hams work on radio antennas, and learned the Army's version of field rigging.

jsw

If you can get some pictures, that would explain it all. If you have a lot of buds, it may be cost feasible to make one, and have it on hand for all. For the loads you are lifting, you wouldn't have to make an incredibly big or strong one, and you could use a winch with a good capacity of cable, or just tag onto the end of the cable with what you occasionally use for hoisting. The main thing is getting some good harnesses and using them right. I just saw a thing this morning where Spiderman went splat on Broadway, his cable snapping, So, even when you know how to do it right, you can still get a boo boo.

Steve

I have a set of shear legs and a shop crane with off-pavement wheels that will lift a ton or two as high as I need. I really want to learn more so I know better what jobs to take or avoid, for myself or as favors for friends.

jsw

All those 3000' refs should be 2033' per fox16.com link below, or

For example, " 'Apparently the top of the temporary jack cable we had up top pulled out of the clamps at the anchor and let the top (of the tower) bend over. That's what started the whole thing,' says President of Structual Systems Technology Fred Purdy." -- from

:)

Good full body harness, "Y" 100% tie-off shock absorbing lanyard to the back "D" ring, and an extra plain lanyard for positioning via the hip "D" rings. Not especially expensive these days either, and certainly less than your insurance deductible.

I think the suggestion of hiring an antenna guy or a bucket truck were good ones, but if you have to swap out the antenna yourself, another option would be to rent scaffolding and that way you can work from a stable platform. Antenna's seldom need service so the rental expense would be a one or two time event, a whole lot cheaper than cable or dish TV.

Roger Shoaf

Up against a building ? Never mind. I'd put the hinges on first and then cut those two ... Look at off grid wind power designs.

SW

I have a set of shear legs and a shop crane with off-pavement wheels that will lift a ton or two as high as I need. I really want to learn more so I know better what jobs to take or avoid, for myself or as favors for friends.

jsw

For the size towers you are talking about, you will find that in comparison to the equipment, knowledge, and experience you already have in your work pool, this will be TinkerToys. But the first experiences will be learning ones, and never having done it before, you will have a bit of a learning curve. Maybe you could advertise for an experienced hand, maybe get an old oilfield derrick erector, or tower erector, and have him/her/it give you a jump start. You might even pick up a gin pole cheap and save yourself that part of the equation. Advertise on craigslist, it's free. Try in Houston, Lafayette LA, and other oil centers. You never know.

Steve

OK, I can tell you how to do it. You need a bit of clearance round the mast, least a foot, preferably more. I've done it, still standing. (And stuff all this "Weldor " crap going on here - the ONLY commercial weld in the whole structure I built - bout 7m tall - broke - migged, looked good, but f*ck all penetration.) I rebuilt it meself with my little DC inverter welder. And thinking a bit about a decent design. Spacers between the 2 plates, enabled decent weld to hinge structure. Used ordinary 25c washers, tack welded them in. so much for "Professional Weldor"

Basically, you need a gin pole stood next to the mast, high as possible, preferably half the height. Needs to be dug in and concreted, its your lowering point via a winch. Bout 50mm sq, 2mm or better would be cool.

You want more, let me know. Not an engineer, just someone who builds things.

Andrew VK3BFA.

You missed the point. Teenagers are fearless and immortal. Hire one for a day. The experience will likely change his (or, if you're lucky, her) life, but there is an unending supply of teenagers.

-Frank

Domain offline, Frank!

Unfortunately, I have visited your site before and can't afford one of your _nice_ knives. What do you think of the Cold Steel Kobun tanto?

(Apologies for posting a metalworking-related question here on RCM)

-- Remember, in an emergency, dial 1911.