Posted: 10/22/2011 6:06:54 PM EDT
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I have an old 40' POS TV tower bracketed to the east end of the house. It holds a now unused TV antenna, the center of my dipole, a 3G repeater yagi. I'd like to replace it with something more useful, where I could put an HF beam of Log Periodic on top, and maybe even a VHF beam. I've been kicking this around for a while. If I went w/ a guyed tower, it would need to be some 250-300' from the house to have an area with enough clearing, and the XYL is pretty strongly against this. In looking at Rohn's website, it looks like they have a bracketed version of the 45G, but it requires two brackets, one at 20-some feet. We have a single story ranch with the roof peak @ about 12', so this won't work. The HF antennas I'm looking at are between 6 and 8.5 sq ft wind load. The VHF beams seem to range from <1 to about 3. And I'd also like to have a VHF/UHF vertical. Does such a thing exist that will allow me to get all of this junk 35-45 feet up in the air? If it does, I can't seem to find it... Thanks in advance, -Slice |
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If I have to and it's possible, sure. I'm afraid the house will be in the way of at least one of the guys, though. I'd really like to get a good antenna up in the air for the upper HF bands while the sunspots are hot, all I have is crap right now. So –– I'm open to anything I can talk the wife into that doesn't break the bank... |
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Well this is just me. Go to the hard ware store and get.
-A bag of quickcret* -Lots of cable (200'?) depends on mounting position -Some clamps -a good sized eye bolt -some re bar I would lay out a 3 point mount. Say your houses bracket is at 10', then at 20' would attach the 3 individual cables. 1 of them would go down to the peak of your roof. That's where the eye bolt comes in. Drill a hole and drop the eye bolt through. on the back side I would make a brace our of angle iron and a 2x4 to distribute the weight. then at about 120* apart layout your two spots to dig holes for your anchors. dig a good deep hole and bend the re bar in to an L at the bottom and an U at the top. this will be your anchor point. mix up the quickcret and set your re bar. Run your cable and your done. Two things to remember 1 never saddle a dead horse! when you double the cable back on itself to attach the clamp make sure its the U bolt part on the short end of the cable. the short end is called the "dead horse" and the plate that clamps down is the saddle 2 when you make the U's on your anchors, put the opening away from the tower. This prevents a "worm hook" Just a thought |
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Quoted: Well this is just me. Go to the hard ware store and get. -A bag of quickcret* -Lots of cable (200'?) depends on mounting position -Some clamps -a good sized eye bolt -some re bar I would lay out a 3 point mount. Say your houses bracket is at 10', then at 20' would attach the 3 individual cables. 1 of them would go down to the peak of your roof. That's where the eye bolt comes in. Drill a hole and drop the eye bolt through. on the back side I would make a brace our of angle iron and a 2x4 to distribute the weight. then at about 120* apart layout your two spots to dig holes for your anchors. dig a good deep hole and bend the re bar in to an L at the bottom and an U at the top. this will be your anchor point. mix up the quickcret and set your re bar. Run your cable and your done. Two things to remember 1 never saddle a dead horse! when you double the cable back on itself to attach the clamp make sure its the U bolt part on the short end of the cable. the short end is called the "dead horse" and the plate that clamps down is the saddle 2 when you make the U's on your anchors, put the opening away from the tower. This prevents a "worm hook" Just a thought Will a guy anchor on the roof provide enough support, while not damaging the roof? |
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Thats what I was hoping. I'm a little worried that there'll be 30' of tower above the bracket. I'm also worried about the concrete as you mentioned. I'd have to pour it pretty close to the foundation of the house, and not sure what size block I'd need. Since it's not really a supported config by Rohn, having a little bt of a tough time finding specs on how it needs to be built. Any guidance you could offer would be awesome. Thanks, -Slice |
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I haven't looked at the website lately but when I last built some towers (several years ago) the Rohn catalog had all the specs for both guyed and house bracketed installations of 45 and their other towers. Put in a couple of LMR towers with IIRC ~55' of tower above the bracket, supporting a 20' vertical antenna, which was at the max for their specs. I can't remember how much concrete we put in, 1 1/2 yards or something like that if memory serves. I went with the Rohn specs plus just a little extra on concrete volume for that height.
Earlier this year I helped take down some antennas for a retired amateur that was moving. He had a Mosely 3 element tribander with the add-on 40m kit, along with a 11el 2m yagi and a 2m ringo ranger on top. On top of 5 sections of Rohn 25, part of the bottom section in concrete, and a house bracket about 15' up from the base. I was told this tower had been there since sometime in the early to mid 80s. If 25 worked for that, 45 should be pretty solid for what you're describing. |
| The key to anchoring it to the roof is the brace you put on the inside of the roof. A 3/4" hole through the roof wont compromise the roof, and some 5200 marine sealant will keep the water out. I would have a 24" 2x4 on the inside and some fender washers in between the nut and 2x4 |
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Quoted: I haven't looked at the website lately but when I last built some towers (several years ago) the Rohn catalog had all the specs for both guyed and house bracketed installations of 45 and their other towers. Put in a couple of LMR towers with IIRC ~55' of tower above the bracket, supporting a 20' vertical antenna, which was at the max for their specs. I can't remember how much concrete we put in, 1 1/2 yards or something like that if memory serves. I went with the Rohn specs plus just a little extra on concrete volume for that height. Earlier this year I helped take down some antennas for a retired amateur that was moving. He had a Mosely 3 element tribander with the add-on 40m kit, along with a 11el 2m yagi and a 2m ringo ranger on top. On top of 5 sections of Rohn 25, part of the bottom section in concrete, and a house bracket about 15' up from the base. I was told this tower had been there since sometime in the early to mid 80s. If 25 worked for that, 45 should be pretty solid for what you're describing. They do have some specs for both, but nothing that matches exactly what I'm trying to do. I'm leaning towards gcw's idea of bracketing the bottom, and seeing if I can guy the top. It's a little scary since I'm a tower newbie, and I don't know if I can find someone to help me put it up if it's not exactly to spec. I can't climb it myself –– I'd puke half way up. Thanks for the help -Slice |
Could you lay it down? You may look at building a "dead horse" pretty much its a pole say 10' tall with a groove (an old 14" wheel works well  ) welded to the top. you would sink it in the ground about 10' away from your tower. The idea is that the cable to your winch runs up to the top of the dead horse and over to the tower and makes it a one man job to lay it over and stand up
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Quoted: Could you lay it down? You may look at building a "dead horse" pretty much its a pole say 10' tall with a groove (an old 14" wheel works well ) welded to the top. you would sink it in the ground about 10' away from your tower. The idea is that the cable to your winch runs up to the top of the dead horse and over to the tower and makes it a one man job to lay it over and stand upI don't think I can. There's an awful lot of trees around that end of the house. |
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Hmm well have you thought about a crank up tower?
LINK Thats just the first link in the google search there are plenty more brands. |
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Quoted: Ummmm... I may know where there's a freestanding tower just laying on the ground waiting for a new home. Since I know how far away you are it might be worth your while........ That'd be awesome! PM inbound... ETA: Your PM box is full, please shoot me a note when you get some time. |
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Wish I was closer, I climb the little 'short' ones all the time and I have a couple of dozen section of tower taken apart behind my shop. I am by no means a professional, but I have worked around a lot of the guys who were while they were building them an asked a LOT of questions in an effort to be safer.
On several Rohn 25 builds they dug a 3x3x5' deep hole, made a rebar 'cage' and filled with concrete...1 1/2 sq yds or there abouts. Be safe around that thing, and be sure to watch for power lines! Joe |
| I took a 50' rohn 45 tower almost a year ago. It was bracketed about 12 feet up on the side of the house and had been there almost 40 years. In fact after I had it on the ground he told me that the 5 sections that I took down were the only sections of a 210 foot tower that was taken down by a snow storm back in the day. It had a mosley tri bander and a small 2m beam with a vertical. That tower did not move even with my largness up there. It has been through 3 tornadoes at least. It is going up at my qth unbracketed up at least 40 feet this next spring. |
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Quoted:
Looks something like this: http://www.cellantenna.com/public/img/layout/cay819.jpg We get our internet via cellular, and this thing 25' or so up on the tower is the only way we can get a signal. It's pretty small –– maybe 20" long. How's that working for you? speed? Cost? We do have DSL in the area, but it starts at $69.99 a month for 768k service. |
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Quoted: Quoted: Looks something like this: http://www.cellantenna.com/public/img/layout/cay819.jpg We get our internet via cellular, and this thing 25' or so up on the tower is the only way we can get a signal. It's pretty small –– maybe 20" long. How's that working for you? speed? Cost? We do have DSL in the area, but it starts at $69.99 a month for 768k service. It's about $50/mo. Because it's a corporate account I still have unlimited usage, which I don't think they do for consumer accounts anymore. Speed sucks for the most part. It'll burst over a meg sometimes, but on average it's probably 250K or so. Better than a modem, but nowhere near DSL. It's pretty high latency, ~150-200ms. |
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Quoted:
Quoted:
Ummmm... I may know where there's a freestanding tower just laying on the ground waiting for a new home. Since I know how far away you are it might be worth your while........ That'd be awesome! PM inbound... ETA: Your PM box is full, please shoot me a note when you get some time. Responded. Sorry. Once the membership went I guess I lost PM space. 
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