Dual Repeaters

[WQOC472]

Hello, I have 2 Motorola GR 300 Repeaters (i am currently using one of them on GMRS 462.6750) i have recently purchased a second one. My question is; Can i put both repeaters on the same frequency (i get around 5-7 miles out of the existing repeater) If i put the second repeater around 5 miles away from the existing repeater, will that work? Basically i am wanting to double my range. Let me know the easiest way to do this.

Thanks,

 

[fineshot1]

Hello, I have 2 Motorola GR 300 Repeaters (i am currently using one of them on GMRS 462.6750) i have recently purchased a second one. My question is; Can i put both repeaters on the same frequency (i get around 5-7 miles out of the existing repeater) If i put the second repeater around 5 miles away from the existing repeater, will that work? Basically i am wanting to double my range. Let me know the easiest way to do this.

Thanks,

Sure you can do this, but if i were you i would not have the same access tone on both of them.
I would make them both different so a mobile user does not key up both at the same time
which could cause receive problems on the mobile user end. Just make the locations and
access tones known to all users and they can program one memory with one tone and a
second memory with the other. This is assuming you and the users are using programmable
equipment.

 

[WQOC472]

Basically i have the existing repeater on the West side of town and i am wanting to put the second on the East side of town. That way i have coverage all around town as well as the West and East sides. Now my next question is, if i set it up this way, i live on the west side of town, and thats where the existing repeater is at, if i put up the second repeater on the east side of town at a friends house, who i talk with often, on the existing repeater he can barely hit it from his house. its around 7 miles, will him and i be able to transmit on the same frequencies (462.6750/467.6750 141.3pl) and hit the east and west repeaters at the same time and be able to hear each other?

I guess i am trying to link 2 repeaters together??

The antenna is up in the air around 30ft running LMR-400 coax.

And yes, we have Kenwood Radios that we can program easily.

Thanks so much for the help.

 

[n5ims]

With two repeaters on the same frequencies and tones you won't double your range, but will instead cause interference that'll pretty much make both unusable. With both using the same tone folks with strong signals will trigger both repeaters and they'll receive both repeaters signals and hear the distortion due to the signals mixing. With both using different tones things will be better (since users will control which repeater keys up), but if one person uses one tone and another the other tone both repeaters will still be active and the distortion will be back.

What may work (check the rules, etc. for legalities on GMRS) is to set up some remote receivers that feed the main repeater using a controller made for that function (often called a "voting controller"). What will happen is the repeater transmitter will use the audio from the receiver with the strongest signal. This is often done on conventional systems to help out coverage in areas that need some help.

 

[n5ims]

Basically i have the existing repeater on the West side of town and i am wanting to put the second on the East side of town. That way i have coverage all around town as well as the West and East sides. Now my next question is, if i set it up this way, i live on the west side of town, and thats where the existing repeater is at, if i put up the second repeater on the east side of town at a friends house, who i talk with often, on the existing repeater he can barely hit it from his house. its around 7 miles, will him and i be able to transmit on the same frequencies (462.6750/467.6750 141.3pl) and hit the east and west repeaters at the same time and be able to hear each other?

I guess i am trying to link 2 repeaters together??

The antenna is up in the air around 30ft running LMR-400 coax.

And yes, we have Kenwood Radios that we can program easily.

Thanks so much for the help.

30 feet won't give you very good coverage (as you can see). A better option might to raise that antenna quite a bit, say 75' to 100' which should greatly increase your range. If possible it may also be good to locate it at a midway point so you're both about the same distance away.

One other thing to reconsider is the use of LMR-400 coax. While it is good for normal scanner and even normal transmission, there are serious issues using it in a duplex opeation (like a repeater). LMR coax (and several others with a similar design) have quite bad PIM (passive intermod) numbers. You may want to upgrade to a commercial grade coax like some Andrew Heliax like LDF4-50A. You'll get lower loss as well as good PIM numbers.

 

[WQOC472]

Higher antenna location (which i had planned on doing anyway) and Better quality Coax.

Would a UHF Amp help as well?

 

[n5ims]

Higher antenna location (which i had planned on doing anyway) and Better quality Coax.

Would a UHF Amp help as well?

It may help, but it may also cause additional issues (like intermod or desense of the receiver). There are similar issues with adding a preamp (unless that preamp is specifically designed for use in that specific repeater design).

Ideally a repeater should transmit only as far as it can receive signals. One that has a very powerful transmitter (but not nearly so great of a receiver) is called an "alligator repeater" (from the alligator's large mouth). One that receives much better than it transmits is called an "elephant repeater" (from the elephant's big ears). Many folks indicate "An elephant repeater is always better than an alligator repeater" since the "elephant" allows weak signals (from a handheld) to still be heard in an emergency while the "alligator" often just causes additional interference without any real useful purpose.

 

[WI8X]

Why not increase the height of the existing repeater and save the other repeater as a backup in case of lightning strike or other radio problem(s)? You mentioned you have the repeater at one end of town but want to extend its range. My suggestion here is to move the repeater to a tall building in the center, (or as close to the center), of the area you wish to cover. In this way the units on the east side and the west side will both have decent coverage. I have to agree that putting up another repeater on the same channel will cause nothing but problems. Likewise, putting a different PL code on it won't do any good if someone on the east keys the repeater while someone on the west is transmitting. You'll just hear the FM groan of two colliding carriers. Move the repeater to an area where it (the repeater) is about 1/2 way between the east/west and you should be styling. Remember, height is might. The higher the antenna the greater the coverage. But along with height comes interference. Maybe a PL should be replace by a DPL or DCS tone. Consider using half inch or 3/4 inch Heliax antenna coax as well. You'll want to get as much of the signal to the antenna.
LMR-400 is great for short runs, but to maintain the quality of received signal as well as the transmitted signal you should be looking at some quality cabling.

Chris