Repeater Antenna

[WQOC472]

I am looking for an antenna for a Motorola GR300 UHF 40 watt Repeater with duplexer. I am looking for a Good antenna for use with this. I have a 30 ft. tall mast to install the antenna on. I was looking at a Omni Directional Antenna??? The repeater has a "N" connector on the duplexer. Any ideas would be greatly appreciated!

Thanks,

 

[davidgcet]

30' ain't gonna give much range unless you are up on a high ridge. what size is the mast, that will determine how large an antenna you can use. a GOOD omni antenna is going to cost you about a grand new, a cheap but half decent base station omni will run from 100-500.00. if the repeater is not already setup on your licensed freqs, expect to pay a few hundred bucks to get it programmed and the duplexer retuned. you cannot tune those duplexers without the proper equipment, even with the right equipment they can be a PITA.


is this for GMRS or HAM, cause the GR300 is not NB capable and must be put out of it's misery by 1/1/13 for all other UHF uses.

 

[WQOC472]

This is a Repeater i got to use with GMRS, It is already tuned and set up on GMRS Freqs. I had a Motorola Dealer Program it up for me. So im good for the NB switch as well. The mast is 1 3/4" Mast. The Building is aprox 20ft tall with a 10 ft mast, to make the total height around 30 ft. in terms of range, I will be using this out in a open area (for a local family farm useage) with no other buildings in the way. just flat Kansas plains and pasture land.

 

[mass-man]

Then the next question will be, what distance(range) do you want to cover? That will be determined by the gain of the antenna, how far the transmitter will be housed from the antenna and the quality of the feedline between the two. More range means a better, more expensive antenna, and better feedline. I am sure davidgcet know the formulas by heart.

 

[WQOC472]

I would really like to get around 5-7 miles out of the repeater. We use Kenwood TK-3160 and TK-3180 Handhelds and TK-840 Mobiles.

 

[n5ims]

I am looking for an antenna for a Motorola GR300 UHF 40 watt Repeater with duplexer. I am looking for a Good antenna for use with this. I have a 30 ft. tall mast to install the antenna on. I was looking at a Omni Directional Antenna??? The repeater has a "N" connector on the duplexer. Any ideas would be greatly appreciated!

Thanks,

An omni-directional antenna should be used unless your users will always be either very close to the repeater or in the direction the antenna's pattern points. Since the repeater has an "N" connector, your cable will need to use one on the base end of the coax. The antenna can easily use a different connector on the antenna end of the coax where you should use the one that mates with the antenna (you can have an "N" connector on one end and a PL-259 or other connector on the other end if that's what is needed to mate directly with your chosen components).

Your antenna selection should be based on what your answers are to the following questions (please note that the answer to one question may limit the options available to answer the other questions)
1. What is your budget? (Good antennas aren't cheap!)
2. How sturdy must your antenna be (handle normal winds or hurricane force with heavy ice build-up)?
3. How much gain is required (note that this is required, not desired)?
4. How large of an antenna can be used?

Some options are:
* DB Products line of omni, exposed dipole antennas like the DB-408 or DB-420. Strong, reliable, expensive.
* Ham band UHF or dual VHF/UHF antennas like the Comet GP-6. Fairly high gain, fairly low cost, may not last as long as commercial grade antennas (or be allowed on commercial towers).
* Homebrew UHF groundplane, j-pole, etc. Cheap, more work, reliability depends on work you put into it, easy to build spares for quick replacement.

GMRS Outlet LLC*::*Antennas*::*UHF - Fixed Antennas (Base / Repeater)
NCG New Product Detail

 

[shad1one]

Repeater antenna

Check with Kreckman Antenna Cresco,PA they have been making antennas for years very well made antenna had one on VHF repeater 20 + years only took it down once for minor repair

 

[rfradioconsult]

Be careful of some antennas with mechanical joints or hardware that can corrode. They tend to create noise when the wind blows due to poor electrical connections, go with a good commercial design.

 

[popnokick]

For 5-7 miles over the flat Kansas terrain around your GMRS repeater antenna mounted 30 ft in the air, you will have no trouble achieving perfectly usable signal... even for handhelds. Spending multi-hundreds to even a thousand on a commercial-grade UHF antenna is unnecessary. At the prices of the antennas I've provided page links for below ($70-$200), you can afford to try one and if you don't like it, replace it. If it doesn't last more than a couple years, take it down and replace it. I'm willing to bet it will last more than a couple of years if properly installed, however. My GMRS repeater has been running in my garage with a 6dbi gain ground plane mounted on 20 feet of mast for 3 years now. My coverage is 15-20 miles in the hilly terrain of PA, and I'm not in a high location. I think I paid about $75 for my antenna, a Diamond gain ground plane. One thing not to skimp on: coaxial cable and a good lightning protector. I have LMR-400 coax, an Alpha-Delta lightning protector, and an 8 foot ground rod (should have more than one ground rod, but I only could get one driven into this rocky soil). Here are some antennas that will do the job for you, and are comparatively inexpensive:

Opek UH2401 UHF Base Antenna Product Reviews

tram uhf base station repeater antenna ham gmrs frs

CA-712EFC Comet GMRS base antenna 9 dBi gain fiberglass

 

[radioman2001]

I second that you should go with an antenna that has welded joints. Poor connections, as a result of movement or corrosion are a big noise maker with duplex systems. Commercial antennas are your best bet, an open bay antenna is what I would use. The fiberglass sticks become noisy after awhile from all the bending back and forth. The extra cost of a good commercial antenna offsets all the work of replacing the antenna multiple times.

 

[LtDoc]

All things considered, and barring any of those "I forgot that" thingys, I don't see why a simple (cheap) antenna wouldn't satisfy your requirements. I would have to agree that a good feed line would be very nice. From there it's just a matter of your budget/preferences. (Being naturally 'cheap', I'd make a 'J'-pole.)
- 'Doc

 

[WQOC472]

How about this one???

Tram/Browning BR-6145 [Tram/Browning BR-6145] - $69.95 : The Antenna Farm :: , Your Two Way Radio Source!

 

[radioman2001]

I don't know how it's made inside the fiberglass shell, any solder joints could come loose and create noise, if it is just a whip with some turns in it that would be good.

 

[WQOC472]

Found some LMR-400, Will this work? I need about 40 feet of Coax. And heres a stupid question, The Antenna in the link i recently posted showed it has a direct termination N Female connector. So this means i need a N male connector on the coax correct?? The repeater also has a N female connector.

Times Mic LMR-400UF [LMR-400UF] - $1.22 : The Antenna Farm :: , Your Two Way Radio Source!

 

[davidgcet]

you need an N male on both ends of the line, and preferably get a polyphaser for lightning protection.

 

[mass-man]

Yes, and I would have them install the connectors. But be darn sure 40ft. will do it! If that antenna has a female N, then you are good to go. Once installed, I would treat the antenna/coax connection with all kinds of weatherproofing stuff. Water in the coax will destroy it in short order. If you bought the repeater from a MOTO dealer, I would ask them if a 5db gain antenna, with a 40ft. run of LMR400 with an antenna height of 30ft will give you the range you are looking for. Might need to improve the antenna...more gain means more $$$ but worth it in the beginning instead of installing everything only to find it craps out about half a mile from where you want the signal.

And don't forget lightning protection...

 

[popnokick]

kzza3175 - Assuming you feel the need, you'll be able to predict the coverage of your repeater before installation using the Radio Mobile software Radio Mobile WEB Site

Takes a bit to learn it, but it is very accurate if you put in the correct parameters reflecting your planned setup (antenna height, gain, type, power input, coaxial loss, etc.) The software uses NASA Space Shuttle radar topography data to compute the terrain at your location.

I'll write it again: If your local terrain in Kansas is flat, you will be able to make a lot of mistakes in your setup and still get 5-7 miles range with your 40W repeater. But do it carefully (professionally tuned duplexer, properly installed N connectors and coax, grounding, lightning protection, waterproofing) and you'll get much more than 5-7 miles... and a much longer life out of the entire system.... even with the "cheap" antenna you're getting. Which IMHO will be fine for what you're trying to do. It comes down to what your time is worth for maybe 4-6 hours once every 3-4 years vs. $1200 to $2000 for a 4-bay DB Products dipole.

 

[kayn1n32008]

Wirelessly posted (BlackBerry9630/4.7.1.57 Profile/MIDP-2.0 Configuration/CLDC-1.1 VendorID/109)

Stay away from PL-259 connectors on Uhf. Use decent connectors, silver prefered. Stay as far as you can from cheap nickle plated ones.

 

[mpddigital]

For the install you are doing you do NOT need Ultraflex (unless you really want to spend the extra $$$) Standard Times Microwave LMR-400 will turn 90 degrees in 1 inch without attenuation. That will work fine since you are not on a rotor. Use N males on both ends if you can. PL-259s are much more prone to issues and you can water proof the Ns better. Yes the connectors on your coax should come shrink wrapped. Yes you still need to properly water proof the connections

There are other coax brands that will work fine for a VHF repeater but stay away from the cheap commie stuff it you want the cable to last. Commscope, Times, Alpha, Coleman, Suhner are a few of those who make. make good coax. Don't buy a "made-up" brand name where you cn't find out where it's made...

 

[ipfd320]

antenna

i myself years ago purchased the tram uhf reprater antenna on e-bay back then it sold for 85.00-this antenna was good-reception was excellent at 30 ft above ground level i txmitted approx 35-40 miles before not being heard on 25 watts with 1.2 to 1 swr--fully adjustibleto fit your freq needs-the antenna lasted approx. 9 years of punishment-i used it for our react gmrs band.....never had a problem