2 MTR2000 repearters

[TriStateMedic]

Hey, I a bit new to this but I am trying to find out if this can be done. My volley currently runs one mtr2000 repeater running at 100w. No bells and whistles. Just a regular old duplex UHF repeater. the issue we are having is that our portables (ht1250s) do not always hit the repeater. Is it possible to place some sort of booster that the far flung units can hit with their radios? Can another repeater be installed somewhere (maybe a low powered one) that would allow a far off unit to hit the main repeater?. If I'm not being clear let me know. We just want the small portables to be able to hit the repeater we already have without screwing up the x-missions or having echos or anything like that. Thanks.

 

[RKG]

The standard approach to a "talk in" issue (i.e., from some parts of service area, portables can hear the station but cannot reliably get back in) is one or more "satellite receivers." Issues:

Need sites.
Need receivers (pretty straightforward).
Need comparator (pretty straightforward but a tad expensive).
Need to convert existing "in cabinet" MTR2000 to wireline use (pretty straightforward).
Need to establish "haul back" modes from station and receivers to comparator. ("Haul back" could be leased phone lines, owned fiber; do not recommend owned RF links.) This is the hard part.

 

[dave9600]

Hey, I a bit new to this but I am trying to find out if this can be done. My volley currently runs one mtr2000 repeater running at 100w. No bells and whistles. Just a regular old duplex UHF repeater. the issue we are having is that our portables (ht1250s) do not always hit the repeater. Is it possible to place some sort of booster that the far flung units can hit with their radios? Can another repeater be installed somewhere (maybe a low powered one) that would allow a far off unit to hit the main repeater?. If I'm not being clear let me know. We just want the small portables to be able to hit the repeater we already have without screwing up the x-missions or having echos or anything like that. Thanks.

You could install a bi-directional repeater but you would have to change channels on the subscribers in the problem areas. The way it works is you program a simplex frequency into your portables and one side of your bi-directional repeater is programmed to receive on this frequency and then key up the other side of the bi-directional repeater on the MTR2000 receive frequency. It works the same way in reverse. The bi-directional repeater receives on the MTR2000 transmit frequency and then keys up the bi-directional repeater on the simplex frequency in your portables. You would need to build this repeater or purchase a used CDR or GR series repeater and program it for bi-directional use.

The other option is satellite receivers. That gets expensive.

Another option is to do away with analog and use Mototrbo IPSC instead!

 

[RBMTS]

I'd suggest considering lesser expensive options. It's difficult to answer your question without knowing more about your current geography, topography, needed coverage area, and current radio system. In many cases, improving on your antenna and feedline can go a long way to helping get more coverage. Does your current system run on a gain antenna? If not, changing to one can be a plus. Can the antenna be increased in height? If so that would increase your receiver coverage. What type of cable is running to the repeater? Hopefully a low loss hardline to the duplexer. If not then think of changing. I have actually seen some installations running on RG-58 which has extremely high loss at UHF frequencies.

Another idea is to look at the portables. Are they running small zero gain antennas off the radios? Perhaps changing the antenna's would work? Are the radios being buried into bunker coat pockets when in use creating more body shielding?

There are many, many factors to take into consideration. But again, many some less expensive improvements could help your situation.

 

[K4IHS]

Have your radio service guy check your duplexer. Running 100 watts it may desense the receiver side of the repeater. One thing I always did when I thought there might me a duplexer issue was to temporarily crank the output power way down and see if the portables could be heard better at the repeater location.

 

[TriStateMedic]

mtr2000

Well, we dont really have a radio guy. We have "guy who somewhat knows about radios". As far as i can tell we do not have a gain antenna and moving the antenna someplace higher would only net us another 50 maybe 100ft. But it comes at a cost of moving the antenna 6 miles away from all of us. If that will help we can do it. I was under the impression though that portable to repeater was a function of the power of the portable.

 

[K4IHS]

Let me try again. I assume you're using just one antenna on your repeater. There is a device called a duplexer that allows the antenna to be used both by the transmitter and the receiver at the same time. It usually is located near the radio itself. During operation of the repeater... the transmitter power trying to get up to the antenna can desense the repeater receiver causing poor receive. The duplexer has to be tuned using the proper equipment (usually by a radio tech). One way I quickly checked for desense... was to listen to the incoming signal from a portable. Then crank down the repeater power or put the repeater in non-repeat (listen only) mode. If the portable sounded much better... then I'd tune-up the duplexer.

 

[mikewazowski]

You could try vehicular repeaters mounted in certain trucks.

 

[cmdrwill]

If the antenna and duplexer check out for no desense you may be able to add a preamp on the receiver in the repeater.

A seperate receiver antenna.

 

[quarterwave]

You are going to need a radio Tech. Call the shop.

These are good posts, there are plenty of ways to solve the issue from MRE's to re-engineer at least the Rx side of the system.

I would also say, and with not knowing your system I'll say it lightly, moving the site 6 miles away if you are going to gain at least 100 feet, probably wouldn't notice.

 

[RKG]

Increasing gain on the station antenna, or increasing its height, can have unintended consequences. The most noticeable is the so-called "lighthouse effect," where you increase performance at a distance but begin to sacrifice performance for closer units.

The first question I'd ask is this: in those areas where portables have trouble talking in to the repeater, how to they hear it when the repeater is talking out to them? If the answer is along the lines of "just fine, thank you," then you have a classic talk-in problem.

Far and away the best solution to a talk-in problem is satellite receivers. True, this is not the least costly solution, but not only will you gain those areas that presently don't work at all, you will improve performance in virtually all areas of your service area. Cross-band and vehicular repeaters are, in my judgment, a bit of a kudgy solution that sometimes gain you nothing and always require operator action to work at all; for that reason, they are not recommended for a public safety application.

 

[TriStateMedic]

We thought about the vehicular repeaters but shelved that idea for the reasons above. Upon further discussion with the brass and considering the looming digital trend we just might bite the bullet and spring for a digital system but I am not sure why this would be any better than the analog one now. Can you really get much better range utilizing digital radio? How?

 

[TriStateMedic]

One way I quickly checked for desense... was to listen to the incoming signal from a portable. Then crank down the repeater power or put the repeater in non-repeat (listen only) mode. If the portable sounded much better... then I'd tune-up the duplexer.

That is a great idea. I am going to suggest that to the higher-ups.

 

[quarterwave]

We thought about the vehicular repeaters but shelved that idea for the reasons above. Upon further discussion with the brass and considering the looming digital trend we just might bite the bullet and spring for a digital system but I am not sure why this would be any better than the analog one now. Can you really get much better range utilizing digital radio? How?

In a nutshell, no. Coverage is coverage, and lack there of is, well...you get it.

However if they are considering a new system, then engineer it with coverage expansion in mind.

Many agencies are suffering from lack of portable coverage, mostly because their systems were designed long ago as mobile systems, not portable or in-building.

 

[R8000]

You should seriously consult with a competent radio shop. There are some things people have mentioned that could work, and some that scare me.

If your too far away...then your too far away. You need a serious system upgrade. Maybe hiring a communications consultant is a good first move.

 

[mmckenna]

There are a couple of ways to address this, and most have them have already been covered.

Vehicular repeater
Have a tech go through the system
Higher gain antenna
better coax,
Tower top preamp,
Etc.

One common way of addressing these sorts of coverage issues is to install a voted repeater system. This would involve installing a receiver out at a location that did a better job receiving than the main site.
To do this, you'd need the receiver, antenna, feed line, antenna support, power and a way to get the signal back to the main site. The antenna can be specifically chosen to cover or not cover specific areas.
At the main site, you'd need a signal comparator/voter to route the best audio to the repeater. The voter would have an input from the receive side of the main site, and an input from the receive only site.

Since receivers don't need to be licensed, as a second repeater or a mobile repeater would, this can save some money.

Where it gets expensive is the backhaul to the main site. Getting clean audio from the RX site back to the main site needs one of the following:
Conditioned circuit from the phone company
radio link
IP link (has to be reliable! No Jim Bob's interwebs services run out of some guys basement)
microwave link.

It might be worth checking with other agencies in your area, they may already have a suitable site with the tower, electric service, and if you are lucky, some sort of existing backhaul you can hop on.

These systems are not the type of thing that the "guy who knows something about radios" set's up. Actually, any of these solutions is going to require a knowledgeable person that can design the system, install it and get it working correctly. It won't be a cheap solution, but it will be cheaper than a second repeater. The nice thing about it is that it's always there and always on. You don't need to have a specific vehicle on site with a vehicular extender on board.

Digital won't work miracles, so don't rely on that as a solution. Anyway, as a fire service, you'd want to retain some analog stuff. Digital doesn't always work well in high noise environments.

 

[K4IHS]

Where your radios recently narrowbanded?

 

[TriStateMedic]

Yes, our radios were narrowbanded right before the cutoff date.