First I want to say this is my first post and I have little experience with radios so go easy. First I'll give the situation that I'm looking to use this in. I'm building an off-road/hunting vehicle and I'm looking to build a mobile repeater in the truck to get some extra range out of my hunting parties HTs. I'm not sure what kinda equipment I would be needing. I've been looking at a kenwood tm-g707a as the mobile unit but i'm unsure if this could be used with a repeater. Suggestions would be greatly appreciated.
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gmrs mobile repeater questions
- Thread starter beoulve
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Successfully building a repeater is a pretty ambitious task for someone who has minimal experience with radios.
If you use a mobile radio, plan on getting two. Repeaters must transmit and receive at the same time. This is called duplex operation, btw.
Most (all?) mobiles are incapable of doing this right out of the box without performing some unnatural acts to them. Most modern mobile radios are completely incapable of duplex operation period, end of discussion.
You would also need a duplexer, and some type of simple controller to cause the two radios to operate as a repeater. Then you have to marry all those radios and parts together in some form that actually works, not a trivial task. For someone who isn't into radios as a hobby or vocation, you really don't want to have to learn about things like desense the hard way. Trust me on this.
My suggestion would be to get a used UHF Desktrac repeater on eBay, get it tuned and programmed on a GMRS frequency, and use that. Then the problem becomes one of providing power in sufficient quantities to operate the thing for the length of time you need it - a much simpler task for someone with little experience with radios.
If you use a mobile radio, plan on getting two. Repeaters must transmit and receive at the same time. This is called duplex operation, btw.
Most (all?) mobiles are incapable of doing this right out of the box without performing some unnatural acts to them. Most modern mobile radios are completely incapable of duplex operation period, end of discussion.
You would also need a duplexer, and some type of simple controller to cause the two radios to operate as a repeater. Then you have to marry all those radios and parts together in some form that actually works, not a trivial task. For someone who isn't into radios as a hobby or vocation, you really don't want to have to learn about things like desense the hard way. Trust me on this.
My suggestion would be to get a used UHF Desktrac repeater on eBay, get it tuned and programmed on a GMRS frequency, and use that. Then the problem becomes one of providing power in sufficient quantities to operate the thing for the length of time you need it - a much simpler task for someone with little experience with radios.
i would have thought there would be some off the shelf hardware that would be capable of doing what i was thinking. I was under the impression (correct me if i'm wrong) that police squad cars are set up with a similar setup in particular sheriff cars or others that service rural areas so that their ht would work when they get out of their cars.
There's more than one way of doing that but none of them are simple. The example you gave is one where the manufacturer does all the hard stuff and you only have to pay for it. It isn't a common system, most are custom thingys, and their price will reflect that.
So far it's just a money thing. Depending on which 'off the shelf' equipment you find, you then get into the legality of it, licensing, etc, which is a whole new ball game.
It can be done. Whether it's cost effective for you is strictly up to you.
- 'Doc
(I like venison, but for the potential cost/trouble of it, I can eat a lot of hamburger!
)
So far it's just a money thing. Depending on which 'off the shelf' equipment you find, you then get into the legality of it, licensing, etc, which is a whole new ball game.
It can be done. Whether it's cost effective for you is strictly up to you.
- 'Doc
(I like venison, but for the potential cost/trouble of it, I can eat a lot of hamburger!
)
Most all in-vehicle repeaters I've seen in public safety vehicles are cross-band repeaters, that is, UHF to VHF or 800, or some combination thereof. Not, in the same band which is all that's legal on GMRS. That Kenwood you mentioned wouldn't work because it can only cross-band and they're not meant for GMRS anyway.
Assuming that money isn't too big of a concern what equipment would I need to be looking at to purchase? And as far as legality goes I was under the impression that as long as the repeater was an in-band repeater and the power of none of the equipment exceeded 50 watts the gmrs license would be all i needed to stay legal.
After doing some more research i've found some possible hardware. Would the pyramid svr 200 or svr 250 work for what i'm thinking? I know on the website that they say the svr 250 is capable of in band repeating and is available in uhf frequencies but i couldn't find anything about the svr 200.
Pyramid vehicular repeaters are designed to connect to the vehicle's mobile radio. It's a tool that's used to provide portable coverage at a local incident scene in radio systems where portable coverage is otherwise unsatisfactory. They are low power (like 2 watts), and are usually not full duplex by themselves. They work in conjunction with a separate mobile radio.
This isn't the tool you would need for your application, and you most definitely wouldn't be happy with it.
As for the legalities, read the FCC rules and see what it says for yourself. Part 95... Google it.
This isn't the tool you would need for your application, and you most definitely wouldn't be happy with it.
As for the legalities, read the FCC rules and see what it says for yourself. Part 95... Google it.
But in combination with a proper mobile radio would it work? If the mobile radio were set to the same tx frequency as the ht's rx frequency and the svr were set for the tx frequency of the HTs. If there is something i'm missing let me know. I'm not looking for something to cover huge areas, just something to help the HTs get more coverage in the immediate area surrounding the vehicle. The places we hunt usually have fairly thick vegetation and when we spread out the two people on the extreme edges usually have a heard time hearing each other. Is there a specific section of the part 95 I should be looking at? I appreciate your help and I hope it doesn't feel like I'm beating a dead horse. And to clarify what I said in the opening post I'm new to radios but I'm very adept when it comes to electronics.
It depends on how you define "work". The Pyramid mobile repeaters are intended for a specific application, and we haven't really established that application is the one you want. These things are designed specifically to help an HT talk out of a poor coverage area to, say, a dispatch center or high level repeater, NOT to enhance communications between portables at the scene.
Yes, that could be made to work, after a fashion. The Pyramid unit is a simplex radio. When it's receiving a signal from the mobile, it activates it's transmitter to repeat to the HT, but then pulses it's transmitter off to see if the portable needs to transmit. If so, the Pyramid transmitter stays off, turns on the mobile transmitter, an repeats the HT's traffic out the mobile radio.
In that configuration, you would have one transmitter in the vehicle that NO ONE IS LISTENING TOO... a waste of resources.
How far an area? The SVR200 is 1/4 watt. The 250 is 1/4 to 2 watts.
Are you talking several hundred yards, several miles? Would both of you be in line of site, or near line of site to the vehicle? What is the transmitter power output of the portable radios you will be using?
Subpart A and Subpart E.
That will help. But setting this up will require test equipment and techniques you're not yet familiar with. It'll be easy to screw it up to the point that it doesn't work. You may end up gagging and spitting when you see the cost of the Pyramid units vs. the cost of something else purchased used. It's not at all the approach that I would take to solve the problem.
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mformby
Member
Mobile Repeater
Vertex and Icom make small UHF desktop repeaters that will do what you want to do. If the one you like doesn't have a 12 VDC connector you can get a 12VDC to 117 VAC power converter.
Vertex and Icom make small UHF desktop repeaters that will do what you want to do. If the one you like doesn't have a 12 VDC connector you can get a 12VDC to 117 VAC power converter.
mformby
Member
The Pyramid unit requires two filters, one a band pass and one a band reject. Even with these correctly tuned you will have to have frequencies that are 10+ megahertz apart (the farther the better) and the receiving antenna from the portables as far as you can get it from the mobile radio antenna. It can be done "in band", but it requires a lot of work. Cross banding it works great, i.e. UHF in/ VHF out.
Vertex makes a vehicular repeater also, VXR-1000, which has the same properties (and problems) but is considerably lower in price.
Vertex makes a vehicular repeater also, VXR-1000, which has the same properties (and problems) but is considerably lower in price.
N4KVE
Member
Years ago I had need for such a device. My friend converted a GE Master 2 to be a mobile repeater. It worked great & total cost was under $100. GARY N4KVE
You can do what you want with a true "mobile" repeater. This type of repeater is available (see link). As noted by others, you would also need a mobile duplexer (or two individual and well-separated antennas).
Micro Computer Concepts - Repeaters
As a point of information, I have one of these re-purposed radios and they seem to work pretty well in normal, base-station service. They are intended to operate on typical repeater frequencies, i.e. - adequate separation between TX and RX. I would think the two biggest issues with a mobile repeater would be power (limitations of the vehicle battery) and antenna type(s).
JK
N4KVE
Member
That's basically what my friend made for me using a GE Master 2 instead of an Exec like that guy used. I used a rubber duck to receive the signals from the HT's, & the mobile antenna on the car to transmit. No duplexer needed. GARY N4KVE
willgrah
Member
How far do the antennas need to be apart for that to work properly without a duplexer. Seems like a good solution to the OP's situation.
N4KVE
Member
In my case, the rx ht antenna was attached to the passenger seat headrest. The tx antenna was on the trunklid, so I'd say no more than 6 feet separation. Also we turned the power down to 20 watts as the repeater was only used when the engine was off, & didn't want to kill the car battery. GARY N4KVE
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willgrah
Member
So two 1/4 wave magnet mounts on either end of the OP's truck would make him a stationary repeater. I would like to do something like this a solar generator that I have built. Right now I have a mobile radio wired in and can do simplex no problem, panels keep the battery fresh. A low wattage repeater would be a great addition to the power plant. Good Info!
mformby
Member
Using two antennas is a hit and miss situation. The distance from each other and their gain (if any) is real tricky. If you use a duplexer and a RIC (radio interface controller) you will have no headaches. Using a couple of Motorola mobiles with a specific housing makes a nice, neat package.
Motorola HLN3948B - Basic R.I.C.K. | PartsMotorola.com
mjz55
Member
Not sure if this works for more than HTs but what about the Radio-Tone repeater? Radio-Tone Duplex repeater controller - Radioshop888 KG-UVD1P KG-UV6D TG-UV2 ROIP Repeater Controller Speaker Mic Ham Radio KG-669 KG-689 PX-777 PX-888 FT-897 FT-857 VX-177 VXA-300 KG-679 VEV-3288S V-1000 TG-UV FT-817ND FT-60R FT-897 FT-857 VX-7R VX-
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