GMRS Base antenna

[lu81fitter]

I have been kicking around the idea of getting GMRS radios for around my area. (maybe a 15 mile range) Doing a little research, I cannot find any repeaters close by that are documented. (My search continues) Anyway, I know that a good antenna is the most important investment. That being said, I was looking at a couple of them. They talk about wind load, lateral thrust, and bend movement. This makes me wonder if I need to have a pretty stout or (for the lack of a better word) significant tower/mounting arrangement for them. This is one I was looking at.

Laird Technologies FG4605 - $199.95 : The Antenna Farm, Your two way radio source

Would this be a good option? If I put it up at more than 30 feet, should I have a tower to mount it to or can I use other options like a chimney mount, etc. I live in town and don't have any major restrictions. My chimney is brick and about 19 feet to the top.
Right now, I'm just feeling this project out to see if its worth my while without a repeater close by. Any thoughts would be appreciated.
Thanks.
Tim.

 

[mmckenna]

Laird makes good stuff, and a 5dB gain vertical is a good place to start.
The antenna is 6 feet tall and weighs about 5 pounds. You could do a push up mast, but guying would be important. Towers are nice, if you can afford the tower, and more importantly, afford the installation.

As for coverage, it'll entirely depend on local terrain and how high you can get it.

 

[W8UU]

Laird makes a good antenna. If high winds are common in your area, you are correct in purchasing something that can take a beating. My general rule of thumb is to buy the best antenna, tower, feed line, and lightning protection you can afford, then install it properly and forget it. You don't want to be climbing towers or getting up on the roof to replace damaged equipment every year or so. With UHF, height is key, and the higher you can get that antenna the happier you'll be with your investment. The tradeoff is that higher antennas usually mean a bigger investment in masts, guy wires, towers, and cable. Local terrain and the location of your tower site (valley vs. hilltop in a mountainous area, for example) also figure in to how much you'll need to invest to get the results you want.

 

[lu81fitter]

Laird makes good stuff, and a 5dB gain vertical is a good place to start.
The antenna is 6 feet tall and weighs about 5 pounds. You could do a push up mast, but guying would be important.

How far up would I need to go before guying becomes an issue?

 

[lu81fitter]

Laird makes a good antenna. If high winds are common in your area, you are correct in purchasing something that can take a beating. My general rule of thumb is to buy the best antenna, tower, feed line, and lightning protection you can afford, then install it properly and forget it.

I work in industrial construction, so maintenance is always on my mind. I generally don't want to work on things any more, so doing it right the first time is in the forefront of my mind.
My biggest question is about the wind load. I have an old mount for a satellite dish anchored in the the brick on the side of the house. Could I simply put an extension pole up about 15 feet or so and be safe? Or would the wind take its toll on it? I don't think I would see higher than about 65 MPH gusts in town unless the storm is really bad. Would that be too much for that mount?

 

[mmckenna]

How far up would I need to go before guying becomes an issue?

It depends on what sort of mast/tower you use. The manufacturers will have engineering drawings that cover that.

"Self Supporting" towers are a thing, but expensive. You can do a Rohn 25G self supporting tower up to about 40 feet, but it requires a substantial base foundation. Those are engineered systems, so you'd need to look at local maximum wind speeds as well as how much wind area the antennas, coax and all the other stuff amounts to. I'd not rely on my brain to do that for you on a hobby website.

 

[W8UU]

How far up would I need to go before guying becomes an issue?

I'm not completely sure what you're wanting to do. I've seen just about everything with masts. Generally speaking, if you're using a chimney mount or a rooftop tripod to anchor the mast, I wouldn't go more than 10 feet on the mast then put your antenna on top. If you're buying one of those telescoping masts that can go 40-50 feet up in the air, they need to be anchored in the ground and supported by braces on the side of the building. If you're doing a rooftop (usually a commercial building) telescoping mast, you probably need a commercial grade base bolted into the roof. Guy wires will probably be needed on either installation -- at least one set just below the antenna to stabilize things in high wind. Multiple levels of guy wires may be necessary on taller towers and masts. If you live in an area where snow and ice occur in winter months, you need to think about ice loading on the antenna and mast. Ice adds weight and decreases the ability to bend in the wind.

 

[lu81fitter]

Gentleman, thank you both for your input. It sounds like I need to do more research on repeaters in my area before I pursue this any more. I cannot afford to put up a large installation. I'm in a bit of a valley, so height would be key. Thanks again for your input. This is a great place to learn, especially from knowledgeable people like yourselves.

 

[alcahuete]

My biggest question is about the wind load. I have an old mount for a satellite dish anchored in the the brick on the side of the house. Could I simply put an extension pole up about 15 feet or so and be safe? Or would the wind take its toll on it? I don't think I would see higher than about 65 MPH gusts in town unless the storm is really bad. Would that be too much for that mount?

I use this exact method on a 17'8" antenna. That said, I don't have a mast attached to the mount...the antenna is attached directly to the satellite dish mount. It has withstood 74 MPH winds with no problem at all.

 

[W8UU]

Gentleman, thank you both for your input. It sounds like I need to do more research on repeaters in my area before I pursue this any more. I cannot afford to put up a large installation. I'm in a bit of a valley, so height would be key. Thanks again for your input. This is a great place to learn, especially from knowledgeable people like yourselves.

There's a good bunch of people here. Glad to help.

 

[alcahuete]

I cannot afford to put up a large installation.

Don't get carried away with towers and everything else. You absolutely do not need a tower for a single 6' GMRS vertical. That would be overkill to the Nth degree. A simple mast will do. You can buy a very nice Rohn 43' push-up mast for like $150. Even Home Depot sells them. Put some guy wires on it, and call it a day.

 

[lu81fitter]

I use this exact method on a 17'8" antenna. That said, I don't have a mast attached to the mount...the antenna is attached directly to the satellite dish mount. It has withstood 74 MPH winds with no problem at all.

I actually have a scanner antenna mounted this way with about a 14 foot mast out of the mount. It has survived everything that Mother Nature has thrown at it so far. Probably around 60 MPH or so, but it is just a ground plane kit with a Larsen tri-band on it.

 

[lu81fitter]

Don't get carried away with towers and everything else. You absolutely do not need a tower for a single 6' GMRS vertical. That would be overkill to the Nth degree. A simple mast will do. You can buy a very nice Rohn 43' push-up mast for like $150. Even Home Depot sells them. Put some guy wires on it, and call it a day.

I'm not going to half-*** it! If I decide to go with the GMRS, I'll put up a small TV type tower and anchor the base in concrete, then support it part way up with a bracket off the house. Then, maybe go 20-25 feet above that. It will be home for a couple scanner antennas, my TV antenna, and the GMRS. Not looking to do any maintenance on things. Once and done!!

 

[prcguy]

I also have a big 17+ft Tram dual band antenna on an old DIrecTV Slimline mount. This antenna is very light weight and I would be worried about 15ft of mast then a heavier 6ft antenna on top of that being held up by a satellite dish mount. 10ft or less mast might be ok under those conditions.

I use this exact method on a 17'8" antenna. That said, I don't have a mast attached to the mount...the antenna is attached directly to the satellite dish mount. It has withstood 74 MPH winds with no problem at all.

 

[alcahuete]

I'm not going to half-*** it! If I decide to go with the GMRS, I'll put up a small TV type tower and anchor the base in concrete, then support it part way up with a bracket off the house.

I thought a few posts up you said that was out of your budget, which is why I suggested the mast. If you have several antennas to put up, a tower would most definitely be the way to do it.

I also have a big 17+ft Tram dual band antenna on an old DIrecTV Slimline mount. This antenna is very light weight and I would be worried about 15ft of mast then a heavier 6ft antenna on top of that being held up by a satellite dish mount. 10ft or less mast might be ok under those conditions.

Yeah, I agree with you there. I can't say I would trust a heavy mast on mine in the wind. It seems sturdy, but at some poin, you get a ton of torque at the mount.

 

[lu81fitter]

I thought a few posts up you said that was out of your budget, which is why I suggested the mast. If you have several antennas to put up, a tower would most definitely be the way to do it.

It is a bit out of my budget now. I'll have to wait for a while until I can do it right. Besides that, I need to do more research on repeaters in my area before I get too carried away. This was all just an explorational thing at this point anyway. Wanted to know if I was out of line with my thinking.
Thanks to all !

 

[W8UU]

I'm not going to half-*** it! If I decide to go with the GMRS, I'll put up a small TV type tower and anchor the base in concrete, then support it part way up with a bracket off the house. Then, maybe go 20-25 feet above that. It will be home for a couple scanner antennas, my TV antenna, and the GMRS. Not looking to do any maintenance on things. Once and done!!

If you're looking at multiple antennas and going 20-25 feet above the roof line, a tower is a must. Depending on the wind load, you might need to guy the tower. Don't forget arrestors on the coax and really good grounding. Those antennas can be a nice big lightning rod and you don't want to lose your radio equipment or your entire house to an electrical storm.

 

[CaptDan]

following - I want to eventually put a 40 - 50 foot tower up also - mainly for a repeater/base radio and then a few monitor/scanner antennas.

I would prefer not to have to guy it, as I'd like it close to the house so the coax is as short as possible - otherwise I'd have to move it away from the house a distance to be able to guy it on all 4 sides. Decisions !

 

[lu81fitter]

Growing up in the early '70's, my parents had a tower for TV reception. The nearest small town of about 2500 people was about 6 miles away. It was about 40-45' tall and right next to a 60 acre corn field. No guy wires on it. Just anchored in concrete. It was about 30' from the house. Don't know anything about the electrical protection they had on it.