Mobile Repeaters

[AlexM]

Hello,

I hope everyone is doing well!

I have some questions I’m hoping some people can answer for me.

So, my company I work for does security deployments for disaster zones and other similar situations. We usually get contracted by the state or other agencies to defend people and property from looting. Everyone in the company has their GMRS license and we use them legally for some of our daily operations where we are headquartered out of. 
 

We are wanting to build 10 high powered mobile gmrs repeaters that we are able to put in our vehicles and put in a circle around the perimeter of the disaster zone to provide contact from our HT’s to each other. 
 

What is the best way of doing this. I’ve looked at Simplex repeaters but don’t want to have the same messages repeated twice. I want more of a traditional repeater and also have everyone be able to hear the conversations. I have also looked at the Vertex VXR-1000U units which attach to the vehicles 50 watt mobile unit. I really like how they seem to work. But am not sure how I would go about setting those up to operate to work for GMRS on the same frequency.

Is there any suggestion for equipment or another good way of doing such mobile repeaters.

I know this may be confusing even I am confused a bit over what I wrote.

 

Thank you!

Alex

 

[gortex2]

Have you tried the RT97 or Midland GMRS Repeater ? You'd be surprised how well those will work with a good antenna and feedline. If you can get it in the air (building or hill) with a good LMR antenna and short feedline it will do what you need. Its small, uses little power (one guy is running them on solar) and easy to deploy and store. 

Other options are a part 90 repeater. You can do one out of mobiles but it requires parts to do and again a good antenna and feedline. As reference we used a UHF GR1225 in our SAR command post for onsite stuff. We get about 2 miles around it with a UHF antenna on the command post (FG4600). Not sure if that would suffice. 

Again I'd try the RT97 or Midland for your use first for mainly simplicity. 

The VXR1000 is a vehicle repeater but basically an "extender". They are normally used to boost a low power portable on scene to talk thru a higher powered mobile. Normally this is used in another band but can be used in the same band. In theory you could add a VXR to a 45 watt UHF mobile radio and a duplexer and create a "mobile repeater" but in the end you can grab 2 mobiles cheaper. I've built many VXR based systems but normally VHF and Lowband Mobiles with UHF VXR. Normally they are not used on same band as current subscriber. Will it work yes. But in the end I'm not sure the bang for buck is close enough. 

[Radioguy7268]

Stuff like the VXR-1000 and the Pyramid SVR vehicular repeaters effectively make your portable talk through your mobile radio.

The trouble with using them for GMRS is that they're cross-band repeaters, meaning you would be using a VHF portable to key up your GMRS high powered mobile. That's outside the rules for GMRS - you can't crossband with another service - and there are no VHF frequencies for GMRS.

You could try to do something like a portable repeater, and have a few key personnel set up the repeater on-site with some type of collapsible antenna that might allow you to get an antenna 20 or 30 ft. in the air.  That would increase the range of your portables, but would it be enough? If you've got the funds, you could set up some type of a trailer with a crank up tower, and that would probably get you 75 to 100 ft. up in the air.

Also, you might want to look at some type of a "mic extender" product like the X10DR from Wireless Pacific, which gives you a wireless microphone - allowing you to get a few hundred feet from your vehicle, but still key up on the mobile radio. It's sort of like the vehicular repeaters, but without the cross-banding problem.

[wayoverthere]

56 minutes ago, Radioguy7268 said:

Stuff like the VXR-1000 and the Pyramid SVR vehicular repeaters effectively make your portable talk through your mobile radio.

 

Are there any of those vxr-1000 that work into the amateur bands? I've looked, and everything I've seen on eBay was listed as 148-175mhz.

[Radioguy7268]

Not that I'm aware of, but it would be easy enough to cross-strap your own. The VXR-1000 just puts it all in a nice box, and adds some function lights and a switch for on/off.

 

 

[WRKC935]

Just noticed, this will be my 400th post.  I guess it's worth noting.

 

That being said, portable / vehicular repeaters can indeed be useful in certain applications but need to be thought through during the design phase to get them right.

First question is what are you going to be using for subscribers on the repeater?  If it's only going to be portables (hand held radios) then there is zero need for a 50 watt repeater. The portables will never be able to take back across the full coverage of the 50 watt repeater.  And the repeater is going to have an elevated antenna that further extends it's range beyond the range of portables or mobiles.  If you will be talking to a combination of mobiles and portables, then you need to consider that and POSSIBLY increase the repeater power output but again, the antenna is 20 or so feet in the air, range will be better on the repeater. 

Antenna mounting for a portable / vehicular repeater. 

Best option here is some sort of 2 inch hitch mount that hinges up and into place.  This allows one person to deploy the repeater.  Have a mast that nests together or uses the 4 foot mast pipes that are military surplus and prevalent for amateur radio use.  A quick trip to walmart will get you some heavy velcro straps to fasten the cable to the mast, and make a clean setup.

12 volt POWER

Another reason to NOT have a 50 watt repeater is the power that it will consume.A 10 watt repeater will consume 40 watts LESS power than a 50 watt repeater.  And power source is important.  Simply plugging the thing into a cigarette lighter port will no doubt leave you with a dead battery  at the end of your weekend of fun.  Building some sort of isolated battery plant for the vehicle is important here.  But a couple storage batteries that are in parallel powering the repeater is a much better option than running your start battery dead 2 hours before you pack up in the middle of the woods and everyone else has left the area. 

The idea of 2 portable radios should not even be a consideration.  At minimum you will need to mobile radios and a 'mobile' duplexer to do it right.  And there is a requirement for the repeater to ID.  Now there is no specific WAY it needs to Identify, just that it does it.  This can be YOU the owner or family using YOUR call sign to ID on the repeater while it's being used.  Yes, there are little CW IID boxes that can be used, but that might be something for down the road once you see if it's going to fill your need prior to spending the money for it.

 

[nokones]

12 hours ago, Radioguy7268 said:

The trouble with using them for GMRS is that they're cross-band repeaters, meaning you would be using a VHF portable to key up your GMRS high powered mobile. That's outside the rules for GMRS - you can't crossband with another service - and there are no VHF frequencies for GMRS.

Vehicular Repeaters are Part 90 Type Acceptance and are classed for MO3 operations.  If you use your vehicular repeater for MO3 operations than it is not a crossband operating configuration, by definition. A crossband system would be two Station, in different bands, such as, fixed base or mobile relay (FB2 Repeater) stations interconnected and operating on separate communications systems.

Part 95.1745 allows for remote control of GMRS stations such as repeater, base, and fixed stations but unfortunately, does not allow for remote control of mobile stations.

Radioguy is correct, you cannot legally remotely control GMRS mobile stations, only the aforementioned stations.

I am very familiar with the operation of vehicular repeaters. I was totally involved with the design, operation, and field testing of the GE and Pyramid vehicular repeaters and instrumental in the design concept of the GE vehicular repeaters for Motorcycles. Back in the 80s I did come up with a design of using a vehicular repeater design type concept for an airborne crossband repeater system in an aircraft for a special event moving across the state. That was a fun project.  

[Sshannon]

By definition, repeaters in the personal radio services (part 95) are stations in a fixed location.  I don’t know if that means it may not be moved from one location to another between operations:

Repeater station. A station in a fixed location used to extend the communications range of mobile stations, hand-held portable units and control stations by receiving their signals on one channel (the input channel) and simultaneously retransmitting these signals on another channel (the output channel), typically with higher transmitting power from a favorable antenna location (typically high above the surrounding terrain). 

[WRKC935]

10 hours ago, Sshannon said:

By definition, repeaters in the personal radio services (part 95) are stations in a fixed location.  I don’t know if that means it may not be moved from one location to another between operations:

Repeater station. A station in a fixed location used to extend the communications range of mobile stations, hand-held portable units and control stations by receiving their signals on one channel (the input channel) and simultaneously retransmitting these signals on another channel (the output channel), typically with higher transmitting power from a favorable antenna location (typically high above the surrounding terrain). 

I fully agree with what you are saying, but with Part95 licenses, but there is no requirement to list the repeater location on the license like there is with the Part90 licenses.

I don't know how the FCC would look at a vehicle mounted temporary repeater specifically with GMRS under the rules.  Might be an interesting thing to inquire about to the FCC and see how they respond.

[Sshannon]

58 minutes ago, WRKC935 said:

I fully agree with what you are saying, but with Part95 licenses, but there is no requirement to list the repeater location on the license like there is with the Part90 licenses.

I don't know how the FCC would look at a vehicle mounted temporary repeater specifically with GMRS under the rules.  Might be an interesting thing to inquire about to the FCC and see how they respond.

I agree. As long as the repeater isn’t operating while the vehicle is traveling, it might be just fine. Basically that’s what is necessary for temporary repeaters for emergency situations. 

[WRVD955]

I have a Retevis RT97 setup at my house with a Ed Fong GMRS antenna with cheap coax and it works very well. It sits higher than the surrounding area but I can hit it with a 5 watt HT from 15 miles away no problem.

Also you can watch this video: