vehicular repeater setup

eastfire510

Member
Member
Jun 8, 2010
100
0
Kansas City, MO
Hello all


I am curious on how to set up a vehicular repeater. My county uses vhf radios in the system and by reading the brochures of repeaters it is kinda confusing to me. I know you have 3 parts being the mobile, portable, and repeater but would I have to get a uhf portable to repeat on vhf?
 
There are a couple of different options out there.


1.)There is a company that is called Triad that makes a device that can patch different radios in different bands together. It is called the iOpt Comm-Tac.


2.)I want to say you could do something with VHF Motorola CDM and a UHF Pyramid repeater. A couple of my customers have Low Band CDM radios connected to the Pyramid repeaters and use UHF portables.
 
Motorola made VRS, or Vehicle Repeater System, models of the Astro Specta. There was one for sale here a few months ago that included the VRS Astro Spectra and a UHF HT-750. The old thread is here: http://www.elightbars.org/forums/showthread.php?8188


In this case, your setup would only have two parts: the mobile and the portable. The mobile includes the repeater functionality.
 
shues said:
Motorola made VRS, or Vehicle Repeater System, models of the Astro Specta. There was one for sale here a few months ago that included the VRS Astro Spectra and a UHF HT-750. The old thread is here: http://www.elightbars.org/forums/showthread.php?8188

In this case, your setup would only have two parts: the mobile and the portable. The mobile includes the repeater functionality.

All VRS set-ups have 3 parts (even the above mentioned one one), Mobile radio, VRS unit, Portable. The above mentioned radio was for the radio and VRS unit, the OP would still need a portable to work everything.


VRS units are on E-Bay all of the time: http://cgi.ebay.com/Motorola-VRS750-UHF-Astro-Spectra-Repeater-VRS-750-/320634598576?pt=2_Way_Radios_FRS&hash=item4aa74fb4b0


You need to make sure your radio has the ability to interface with a VRS and then you need the radio to VRS cable, plus a few other odds and ends (Programming of the VRS, programming of your radio to operate the VRS)
 
SlickTop Solutions said:
All VRS set-ups have 3 parts (even the above mentioned one one), Mobile radio, VRS unit, Portable.

That's my mistake. Thank you for improving upon my answer!
 
Just buying a Vehicular repeater off eBay isn't advised. You might be implying that you just need the equipment, but such equipment must be approved for such use by the FCC and the frequencies may require an FCC radio station license. A vehicular repeater designed solely for HAM radio (amateur radio service) may not be type-accepted for use on public safety radio systems. However, the Pyramid radio repeaters are used by many public safety agencies. Cross-banding with a VHF mobile to UHF mobile and portable may also be possible in the UHF radio with certain models of both Motorola and Kenwood Mobile radios.


Consider that you are modifying a radio "system", not just the radios in your car. Are you wanting the vehicle repeater only as a personal use? Is a vehicle repeater system already authorized? Or, are you checking into feasibility for upgrading the capability of all the radios in a local fire department? The FCC license modification costs are usually going to be more than an individual could afford.


Other major precautions and considerations for a vehicular repeater design:


Since you are using the vehicle repeater for other than a law enforcement activity (which has some exemptions involving less than 2 watt transmit power), you will need to use only those frequencies that are authorized for repeater use under Part 90 of the FCC rules and licensed by the FCC for the particular geographic area (15 mile vicinity, county-wide, etc) and emergency service (police, fire, EMS, emergency management, rescue squad?) and be certain that mobile radio and portable transmitter power is limited. For example, if you have a five watt VHF portable, you will usually have to reduce the transmit power into the repeater frequency to one watt and have the output power of the repeater limited ~ 2.5 watts. Also, it depends if you will need a one-way (portable radio to car) or two way (portable to car: car to portable) repeater. Frequencies for the latter application are more abundant in UHF and 700/800 MHz radio spectrum than in VHF - mostly because those spectrum had a shorter range from portable to base station, repeater systems were considered in the radio spectrum assignment. For VHF high band, repeater systems were often an "afterthought", because that part of the spectrum was assigned mostly for simplex radio systems among public safety agencies.


A cross-band repeater, using a UHF portable for a VHF mobile radio, was the typical repeater solution because the portable and car repeater frequencies had to be separated by several MHz in the bandwidth if they were in the same band. (For example, 154 MHz fire frequencies usually needed another repeater frequency in the either the 151 or 159 range.) It also depends if the local VHF radio system is simplex (mobile and base station on the same frequency), or semi-duplex or duplex (separate base and mobile transmit frequencies). Using lower power on the vehicle repeater often means that the frequencies may be closer together, allowing a VHF repeater on a VHF mobile, and allowing you to have the VHF portable radio programmed for both the repeater and normal radio system uses. (Such uses are associated with power reduced to 750 milliwatts or .75 watts on repeater output, and that limits car to portable receiver distance.)


If you local radio system is not licensed for vehicle repeater systems, I strongly suggest you check with your State Frequency Coordinator for the Association of Public Safety Communications Officers (APCO) or the FCC designated Fire/EMS Frequency Coordinator for your area. (In Tennessee, our Tennessee Emergency Management Agency provides this assistance.) The coordinators can advise or provide a list of available repeater frequencies for emergency service use in your area and whether an FCC license change will be necessary.


Also, you may have some other options.


If you need to increase the signal strength of your portable radio to the base station, consider that the portable may need a tune-up or a different portable radio antenna might improve the signal. (The short rubber ducky might need to be replaced.) Or, a newer portable radio might help (if you only have a 2 watt portable, consider whether changing to a 5 or 6 watt handheld radio may be a more cost effective solution that a vehicular repeater.)
 
Pyramid makes fine mobile repeaters, since the OP didn't specify what manufacturer his mobile was I presumed Motorola, hence the link to a Motorola VRS. I'm not sure where tnems got the idea that any of us where suggesting any type of amateur radio mobile repeater set-up.


As a matter of fact, I have yet to see any amateur VRS set-ups per se, I have seen dual band radios that will do cross band operations, but not a true repeater as their is severe lag time for the carrier to drop as well as simplex only operation to/from the portable unit.


tnems does bring up the rest of the issue with regards to frequencies and licensing.
 
Dan (Slick Top Solutions) is correct about few vehicle repeater setups for amateur radio users, since they use fixed base site repeaters. I was just mentioning the point so that public safety radio users check to be sure the radio equipment is approved for Part 90 land mobile radio use. While the Motorola mobile repeaters I have seen were all crossband, our state Department of Transportation uses Kenwood radios and repeaters (Pyramid) that are all in-band VHF, but the portables are tuned way down on power. There are also some field-deployable radio repeaters in the big cities, and smaller systems for incident scene deploymentt are now being acquired through Homeland Security funds.


In other threads, you have mentioned the disguise antenna designs, and the "shark fins" and "film cannister" types merit use for vehicular repeater systems, where a wide band antenna is necessary. As to the FCC licensing issues, I should also advise that in many areas, central dispatch facilities operated by 911 districts might get county wide licenses with authorizations for vehicular or mobile repeater systems. Interoperability frequencies, identified in the National Public Safety communications plan, also have companion vehicular repeater frequencies, particularly in the 700/800 Mhz spectrum.


Richard Land


tnems7
 

Forum Statistics

Threads
54,345
Messages
451,363
Members
19,285
Latest member
mllcolts