VHF repeater for small FD

[BikeFireBill]

FF with a small town combination department and trying to do double duty as the "radio guy" with only a little radio experience. So as not to clog up our main dispatch repeater frequency we send most comms to our "tactical" channel pretty quickly. Unfortunately we cannot talk to members coming in from out of district or from end to end of district. Thinking about setting up a repeater for our tac channels either at the centrally located FD station or on our main first out engine. We have a 50 ft tower at the station but it's mostly leased to a cell company and can't much use it. Top of the station roof puts us about 30ft above ground in a flat district. Do we have to license the repeater separately or can it go under our current license? Found some VHF repeaters online from $500 to $1,000. Sound reasonable? Any thoughts or ideas on this whole thing. Thanks in advance for the help.

[Jim202]

Yes you will need to license a repeater, it will show up as FB2 on the license. It will need 2 frequencies that are spaced at least 0.300 KHz apart or more. More is better. You will need a duplexer to connect the TX, RX and antenna all together. These run from $600 to $1800 depending on just what you need for isolation. Don't forget the cost of the coax, about $300 a foot. Then add about $900 for a good antenna.

You would be better off trying to get your antenna much higher up in the air. You didn't say how much of a distance you needed the radio to cover. This plays a key factor in how high to place the antenna.

Need more info to give you a better answer.

Jim




[quote="BikeFireBill"]FF with a small town combination department and trying to do double duty as the "radio guy" with only a little radio experience. So as not to clog up our main dispatch repeater frequency we send most comms to our "tactical" channel pretty quickly. Unfortunately we cannot talk to members coming in from out of district or from end to end of district. Thinking about setting up a repeater for our tac channels either at the centrally located FD station or on our main first out engine. We have a 50 ft tower at the station but it's mostly leased to a cell company and can't much use it. Top of the station roof puts us about 30ft above ground in a flat district. Do we have to license the repeater separately or can it go under our current license? Found some VHF repeaters online from $500 to $1,000. Sound reasonable? Any thoughts or ideas on this whole thing. Thanks in advance for the help.[/quote]

[Cam]

Don't forget the cost of the coax, about $300 a foot.

[BikeFireBill]

Thanks for the reply. From the station we cover five miles north, five miles south, one mile east and three miles west. Would not need much more coverage than that. Unfortunately we probably can't get on the current tower.

[mr.syntrx]

Don't forget the cost of the coax, about $300 a foot.

What sort of coax is that, 6-1/8" hardline?

[Jim202]

[quote="mr.syntrx"][quote="Jim202"]Don't forget the cost of the coax, about $300 a foot.[/quote]

What sort of coax is that, 6-1/8" hardline? :)[/quote]

Some of us get butter fingers once in a while and then neglet to proof read. I missed the decimal after the 3. It should have read $3. a foot.

That is probably on the low side if you add in the snap in hangers or butterfly hangers. Then again many of the radio shops I inspect work from like to just electrical tape the coax to the tower leg. It cost them a fortune to go back and do it the right way the second time. Especially when they nick the cable and get told to replace it with no charge to the customer. I don't let them re-use the coax connectors, it's brand new out of the bag or box.

Jim

[psapengineer]

Here's a little different perspective:

I'm assuming you're VHF or UHF conventional radio. That said, there is nothing more reliable than simplex (unit to unit) operations. High-rise third sub basements aside, it's likely that you can talk from inside any structure in your jurisdiction to a portable standing outside on the street. After all, most structural incidents are small enough you can throw the portable from one end to the other.

It's also likely that there are basements in your jurisdiction where you can't hit the repeater all the time any time. Plus, if you use the repeater for tactical it's got to be working and your transmissions have to make it from the basement, to the repeater, and back to the outside.

There is virtually nothing more critical than interior tactical operations. There is virtually nothing more reliable than simplex.

So, you've got to ask the question, is it worth abandoning simplex operations to solve the problem of talking to "en-route" apparatus? In my opinion, its not. For most applications I believe interior fire fighting should be done simplex.

Its coming down to the fact that the IC will likely need two radios in the future, one for tactical operations and one for communicating with dispatch and incoming units.

Lastly, on scene repeaters using a mobile can "swamp" the receivers of other on scene portables attempting to use a different channel. So, your mobile, doing the repeating, can swamp the receiver of the IC's portable trying to hear dispatch on the other channel.

Good luck, Bob

[n9upc]

I am going to chime in here and add some things and ask some questions.

1.) It seems to be a small district with only 5 miles north as well as south and 1 mile east and 3 west. In addition you say that it is pretty much flat but you have having trouble with simplex?
My service covers 210 + square miles and we have been using 100 watt mobiles, 5 to 7 watt portables, and 50 to 100 watt bases for about 5 years and have been doing good. Covering almost 12 to 15 miles and more sometimes depending on vehicle as well as unit location.

2.) What are your mobiles rated at? What are your portables rated at?


As of recent my 2 different departments went to a per service only repeater channel and we had some of the concerns you are facing here. The following are some of the main ones:

1.) Location, Location, Location.
Because we are near the Twin Cities of MN our location/height effected our freq. as well as power output. We had a really really nice and high water tower spot and we were basically told you can not locate it there, or if we did it would have to be 50 watts narrowband, and not 100 and wide like we were looking for.
I do not know where you are and if near any big cities running VHF or UHF really really hard. If you are or even if you are not freqs may become a thing far and few in between.

2.) Equipment (both infastructure and filed/subscriber units)
The FCC is really starting to hand out the narrowband licenses here left and right. I am not sure about every where else but here they are unless you can take over an old wideband pair from an agency going to 800 or something.
So with that in mind you may get issued a narrowband repeater pair and then it raises the question of is your end used equipment all narrowband capable. Any MT1000, GP300's, etc... are not and can be converted but you will have to pay for the cost or upgrade.
In addition a $500 or $1000 repeater is going to be on the cheap and crappy side unless your getting something used, and then it is Buyer beware. If it is going to be for public safety use I would strongly suggest something that is continous duty and higher wattage then what you would be licensed for.

3.) Usage and the learning curve.
You stated that this was maybe going to replace a simplex TAC channel for comms. This is a good ideal as we have moved to this sort thing with our departments. However, as stated to many people forget about simplex TAC channels which should be used on-scene and try using a repeater for in building attacks. ( I have a whole set of stories which involved issues I can talk about later some day.)
If you are using it for a TAC repeater between base and IC, or dispatch and your units in route that is great. But, as stated do not go and use it for an interior attack channel.

4.) and finally design and impliment.
Granted you do not need a consultant to run things over and check things out for you. However, you do need to sit down and put some thought into it as to how this repeater is going to be set-up. Are you going to have a gain antenna or no gain? What about power out of the repeater? Factoring in line loss of coax, duplexer loss, antenna gain, and power out to get an effeective ERP to file for on the license.

In closing I would suggest this search the internet as there are programs which will allow you to put in a topo map and enter in your values for the repeater (ERP, Ht., ant gain) and in turn it will spit you out a map of your area which shows freq saturation AT STREET LEVEL!
Sit down and put some thought into it and come back or e-mail us and we will all be able to help and offer some advice. Remember you maybe radio savy but some PS people do not want to be.