VHF Repeater Design

[cdesio]

Hello All,

I am looking for some advise on repeaters, I am working with a small EMS service that desires their own private channel to communicate between mobiles and portables. They currently have 4 rigs with Kenwood TK-790 radios and roughly 15 Motorola HT-1250's, the service area is ~75 square miles.

With a limited budget what would you recommend for a VHF 15x.000 repeater, antenna and tower?

Thanks!

[Jim202]

Well your not going to like it, but unless you already have a license, it will probably take considerable
time trying to get one of the frequency coordinators to spit out a pair of VHF channels for your desires.
But first you will need a location that is high enough to provide the coverage your looking for. Need
the location before the frequency planning can be done.

The antenna, feedline and radio transmit power will all be determined by what the frequency coordinator
tells you that you can have for effective radiated power (ERP). You could end up with anything from
500 watts all the way down to as low as even 10 watts.

What it will cost is hard to even guess at this early in the process. You might be told that there are
no frequencies even available. Rules are different for public safety and for profit businesses. As I
spend all my time in the rule section for public safety, I don't have a clue.

Jim

Hello All,

I am looking for some advise on repeaters, I am working with a small EMS service that desires their own private channel to communicate between mobiles and portables. They currently have 4 rigs with Kenwood TK-790 radios and roughly 15 Motorola HT-1250's, the service area is ~75 square miles.

With a limited budget what would you recommend for a VHF 15x.000 repeater, antenna and tower?

Thanks!

[cdesio]

Jim,

I have been in touch with a frequency coordinator about getting a license and there are certainly frequencies available. This falls under FCC Form 601 and the form we need to fill out requires information about location, antenna height and number of units etc. So before filling out the form for the license I need to have a plan for the fixed base location we will be using..

The site we are using is has above average elevation for the area and is out of the city so obstacles should be limited.

-Chris

Well your not going to like it, but unless you already have a license, it will probably take considerable
time trying to get one of the frequency coordinators to spit out a pair of VHF channels for your desires.
But first you will need a location that is high enough to provide the coverage your looking for. Need
the location before the frequency planning can be done.

The antenna, feedline and radio transmit power will all be determined by what the frequency coordinator
tells you that you can have for effective radiated power (ERP). You could end up with anything from
500 watts all the way down to as low as even 10 watts.

What it will cost is hard to even guess at this early in the process. You might be told that there are
no frequencies even available. Rules are different for public safety and for profit businesses. As I
spend all my time in the rule section for public safety, I don't have a clue.

Jim

Hello All,

I am looking for some advise on repeaters, I am working with a small EMS service that desires their own private channel to communicate between mobiles and portables. They currently have 4 rigs with Kenwood TK-790 radios and roughly 15 Motorola HT-1250's, the service area is ~75 square miles.

With a limited budget what would you recommend for a VHF 15x.000 repeater, antenna and tower?

Thanks!

[ai4ui]

And since Jan. 1, 2013 is just right around the corner, make sure your coordinator finds you a narrowband pair...

[Jim202]

Go for it. Put down a 100 watt transmitter. If the man doesn't like it, he will let you know. The trend
seems to be that the narrow band systems loose coverage over the same system setup that the old
25 KHz channels had. So don't let the coordinator talk you into lower power out if you can help it.

I would put down a gain of 5.25 db for the antenna gain. Again if the man doesn't like it, he will
let you know. This is what you would get from one of the station master or good fiberglass stick
antennas. At the VHF frequencies, unless you have a long coax run, you should be able to get
away with 1/2 inch heliax type cable. With Andrew no longer the top dog, you might end up
with the aluminum junk that is now being sold.

Jim



I have been in touch with a frequency coordinator about getting a license and there are certainly frequencies available. This falls under FCC Form 601 and the form we need to fill out requires information about location, antenna height and number of units etc. So before filling out the form for the license I need to have a plan for the fixed base location we will be using..

The site we are using is has above average elevation for the area and is out of the city so obstacles should be limited.

-Chris

[cdesio]

So any suggestions on repeaters? My first thought was 2 CDM-1250's with the cable to link them, purely from a cost standpoint..

[d119]

For an EMS setup? No but hell no. For life-safety critical systems you can NOT afford to cut corners.

You might consider a MotoTRBO repeater that's set up for analog operation, or if you can afford a little more, get an MTR 2000 and enjoy 100W TX (less duplexer loss).

[cdesio]

D119,

I totally agree for life-safety systems you can cut corners, fortunately our county provides a very well designed and maintained repeater system for critical communications. This system I am designing is for casual communications during events, crew communications and general administrative communications not for communications regarding patient safety.

While I would love to get a MotoTRBO repeater there is no budget for it..

The system will be used for casual communications, our county provides a very well designed repeater system for critical communications.

For an EMS setup? No but hell no. For life-safety critical systems you can NOT afford to cut corners.

You might consider a MotoTRBO repeater that's set up for analog operation, or if you can afford a little more, get an MTR 2000 and enjoy 100W TX (less duplexer loss).

[ai4ui]

Special Events are potential life-safety situations. Plus, if you put it up, it will get used for an overflow channel for some disaster, some where, some time. You would be much better off in the long run to lie, cheat, or steal to get what you need to put up something proper. Go through your state's surplus system. As more & more states go to state wide trunking systems it leaves older, but still excellent and serviceable equipment available for nothing or next to nothing through intergovernmental transfers. I know here in Florida when everybody went to the statewide system (SLERS) a bunch of stuff was transferred to local governments for the price of going & getting it. This equipment had been well maintained & was in excellent shape.

It doesn't need to be brand new, just servicable. Now if someone tries to give you a General Electric Transistor Progress Line repeater you may want to hang up on them.

[cdesio]

Point taken.

Special Events are potential life-safety situations. Plus, if you put it up, it will get used for an overflow channel for some disaster, some where, some time. You would be much better off in the long run to lie, cheat, or steal to get what you need to put up something proper. Go through your state's surplus system. As more & more states go to state wide trunking systems it leaves older, but still excellent and serviceable equipment available for nothing or next to nothing through intergovernmental transfers. I know here in Florida when everybody went to the statewide system (SLERS) a bunch of stuff was transferred to local governments for the price of going & getting it. This equipment had been well maintained & was in excellent shape.

It doesn't need to be brand new, just servicable. Now if someone tries to give you a General Electric Transistor Progress Line repeater you may want to hang up on them.

[cablemonkey]

check out http://www.danelec.com

Very solid product, small, flexible, easy to use and setup.

[dsheli]

I don't mean to Hi-Jack this thread but I to would like to do something similar for my fire dept. We are in rural upstate SC, how do we go about finding who our frequency coordinator is? My main question has to do with the two types of licenses. We obviously fall under the public safety criteria but would that be the best route? Would it be cheaper, easier or quicker to go the business route? If somebody could explain the pros and cons of a PS license vs a Biz license it would greatly be appreciated. Currently our radio line consists of XTS 2500 and 5000 radios that are P25 compatible. Our current county system is strait analog, is there a huge price jump (in the repeater) should we decide to use are radios in APCO 25 vs strait analog.
Thanks for the help.

[Tom in D.C.]

If you type "frequency coordinators" into Google you will come up with this FCC site:

http://wireless.fcc.gov/services/index. ... l_business

[Jim202]

There is nothing in the rules that force you to go P25 on your fire radios. It would be in your best interest
to probably not go digital on your fire channels until Motorola solves the high noise issues with the vocoder
they are using. There have been a ton of magazine article on the subject. NFPA doesn't recommend using
digital on a fire scene. There are just too many issues in using digital at a fire scene. However with that
said, you will always find some people that will say they have never had a problem with digital.

I guess the bottom line is who are you mutual aid agencies and what kind of radios do they have? If you and
they are on VHF or UHF, you will have to migrate to narrow band operation by January 2013. This means
that any old radios in service will probably have to be replaced if they were not purchases in the last several
years. You will have to check on a model by model basis to see if your current old radios can be programmed
to go on the narrow band modulation.

If your radio shop is Motorola, be double sure they are not leading you down the money path. Right now
they are on a kick to sell everyone new trunking systems. You don't need that if your present system
covers your service area and serves your needs. It is a very expensive path to be led down that most
departments don't need. Have heard comments from many agencies that they are being told they have to
get off of their old channels and go to trunking. One of the agencies I heard this about was operating on low
band. Those channels are not even effected by the narrow banding. These agencies are being taken
advantage of.

Jim

I don't mean to Hi-Jack this thread but I to would like to do something similar for my fire dept. We are in rural upstate SC, how do we go about finding who our frequency coordinator is? My main question has to do with the two types of licenses. We obviously fall under the public safety criteria but would that be the best route? Would it be cheaper, easier or quicker to go the business route? If somebody could explain the pros and cons of a PS license vs a Biz license it would greatly be appreciated. Currently our radio line consists of XTS 2500 and 5000 radios that are P25 compatible. Our current county system is strait analog, is there a huge price jump (in the repeater) should we decide to use are radios in APCO 25 vs strait analog.
Thanks for the help.

[Batwings21]

Someone mentioned a MotoTrbo repeater. I would put that in the HELL NO category also. We have many Trbo repeapter installed and a lot of the uhf high power units we have had to cut power down to 20 watts to save the pa's. You need a mtr2000 or even a kenwood tkr790 or something along those lines. The Trbo units advertise themselves as 100 duty cycle, but they are nowhere near that, and according to motorola they are not "Mission Critical" equipment. Just my 2 cents...

[dsheli]

Thanks for everyones reply's! Yall have been most help full. Currently our county operates off a conventional vhf analog system and it looks like we will be staying with that system for a while since we live in a rural part of the country. One thing that is a major plus about living in SC is the state wide Pal 800 system. Currently we have about 8 P25 800mhz radios that our officers carry for administrative purposes and they work really well for that purpose. That is something we would like to replicate to everyone in our dept, not just officers. At $2500 a pop and the $8 dollars a month per radio is it just to expensive and not practical to issue all of our volunteers a 800 and a VHF. We are already light years ahead of our neighboring depts for the sole reason of having an 800 mhz radio. About 3 years ago we received a communications grant so all members have a VHF XTS2500 and officers have a VHF yellow XTS5000R. I know there are allot of variables involved in applying for an FCC license and I am sure many of you have allot of experience acquiring licenses for your customers. Generally speaker what are the average fees and time involved in applying for an FCC license in the public safety spectrum? Would be cheaper and quicker to shoot for a business chunk of spectrum? If there are a ton of factors involved that dictate the fees involved could you please give me a ball park. For example "you could pay on the cheap side, $500 for a license and on the expensive side $5000, all depending on demand and location." Also I know when applying for a patent you need to get a lawyer, is this application process something that we need to contract out with our dealer and have them do or given the spec given to us by our dealer something a department can do?
Thanks for all your time and input!
David

[Tom in D.C.]

If you now have an acceptable, working VHF analog system, and you are not going to add radios to the SC statewide system, why do you need another license?

Also, you don't have the option to request an IB license; you're a PW entity and will be licensed as such if and when you apply for another license.

And if you're thinking about P25 on your 2500s, first check the radios' flashcodes to be sure they are capable of digital/P25 operation.