We're looking to put up a VHF-High repeater for public safety (EMS) use. We're coordinated and licensed for a pair of frequencies (50W ERP) and now looking to go on the air. The repeater is to be located atop the hospital that dispatches us, which is on a hill (small mountain?) and hosts a lot of EMS and FD radio equipment, not to mention some commercial and paging radios (i.e., high RF environment).
So far, I have quotes ranging from a GR500 to a GR1225 to a MTR2000. Besides the obvious things such as cost and the company doing the work, what should we consider (technically) in comparing the different options?
- g
GR500 vs GR1225 vs MTR2000
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CuriousGeorge
- Posts: 124
- Joined: Wed Oct 16, 2002 6:22 pm
Whenever you get bids, make sure they include:
PROPER lightning protection
good antenna- not just a cheapo to be able to win the bid
any filter to reduce intermod form other transmitters
battery backup
The MTR (to me at least) is a real repeater, where the others are just mobiles in a box. The MTR is suited for heavy usage than the others, as they may overheat is the repeater is very busy.
Next.....
PROPER lightning protection
good antenna- not just a cheapo to be able to win the bid
any filter to reduce intermod form other transmitters
battery backup
The MTR (to me at least) is a real repeater, where the others are just mobiles in a box. The MTR is suited for heavy usage than the others, as they may overheat is the repeater is very busy.
Next.....
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thebigphish
- Posts: 1477
- Joined: Sat Nov 29, 2003 10:10 pm
- What radios do you own?: AM/FM
Among other things, since your repeater sounds like it is going t be used for dispatch functions, you should think about how it is going to be controlled. Controlling a repeater via a control station is, for dispatch use, not a good idea. I'd have a chat with someone qualified to design these systems to explore wireline control options.
The next thing I'd think about is whether your service territory and tactical usage is likely to require multiple receivers. Remember that the critical path is not the base station to the portables and mobiles in the field but rather the return path from the field units to the receiver.
For any system that will use wireline control or multiple receivers, a "real" base station, such as the MTR2000, is the only way to go.
Other things to think about: backup power at the station site, backup repeaters (or transmitters) and the control thereof, and implemention of the FBICR (fall-back in-cabinet repeater) function, if you are using a voting receiver system.
The next thing I'd think about is whether your service territory and tactical usage is likely to require multiple receivers. Remember that the critical path is not the base station to the portables and mobiles in the field but rather the return path from the field units to the receiver.
For any system that will use wireline control or multiple receivers, a "real" base station, such as the MTR2000, is the only way to go.
Other things to think about: backup power at the station site, backup repeaters (or transmitters) and the control thereof, and implemention of the FBICR (fall-back in-cabinet repeater) function, if you are using a voting receiver system.
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psapengineer
- Posts: 175
- Joined: Thu Oct 07, 2004 10:00 am
MTR2000
No doubt, I'd use an MTR2000 or even an older MSR2000 before I'd use either of the other choices.
Remember:
Interference Protection against other radios on the site, an intermodulation study, isolation to other same band users, cavities-duplexer, RF Isolator, Lightening Arrestor, Good Transmission Line, Generator backup, battery backup if its used for paging/alerting, check the new input frequency for PL duplications by other co-channel users. it woudn't hurt to also check the output for PL duplications. if you're controling the repeater by wireline be sure the Telco uses "CO" powered line devices.
And, of course, the cost of reprogramming all of the mobiles and portables to use the repeater.
Good Luck, Bob
Remember:
Interference Protection against other radios on the site, an intermodulation study, isolation to other same band users, cavities-duplexer, RF Isolator, Lightening Arrestor, Good Transmission Line, Generator backup, battery backup if its used for paging/alerting, check the new input frequency for PL duplications by other co-channel users. it woudn't hurt to also check the output for PL duplications. if you're controling the repeater by wireline be sure the Telco uses "CO" powered line devices.
And, of course, the cost of reprogramming all of the mobiles and portables to use the repeater.
Good Luck, Bob
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Dan562
- Posts: 533
- Joined: Mon Aug 23, 2004 7:30 pm
- What radios do you own?: Kenwood, Yaesu, ICOM, Motorola
VHF MTR2000 Base Station Repeater
Hello George,
The MTR2000 Base Station Repeaters are sold as a Model T5544 /\/\ Account Rep or T5766 Independent /\/\ Dealership (but they are the same unit). These units are Tone Remote Control ONLY for the Console requirements. The MTR2000 can be set-up as 12.5 kHz or 25 kHz Channel ANALOG Spacing. The MTR2000 Product Line is NOT compatible or upgradable with the new Digital APCO P25 Standard Products. Here are the options you should have on the order form:
X182 VHF Duplexers (Minimum 1.5 MHz Frequency Tx to Rx Separation)
X265 External Preselector (for a High RF Enviroment Site)
X308 46" Cabinet (for the Peripheral Equipment in the cabinet)
X319 VHF Operation
X580 Repeater Operation
X597 Convention Analog
X676 External Double Circulator (Helps prevent Intermodulation mixes)
X 100 Watt RF Power Amplifier (CLN1225)
100 Feet 1/2" 50 Ohm Heliax RF Feedline Antenna Cable with "N" Type Connectors, RF Surge Adaptor and +5.2 dB Fiberglass Vertical Antenna.
*Here's* where I disagree that you need Battery Back-Up for the station.
Generally all large hospitals and medical complexes have Emergency Generators supplying Primary Power to the critical areas in the buildings including the elevators and radio equipment rooms. Tou can order the Battery Back-Up DC Supply and required Batteries but it will be redundant to the hospital's emergency power system.
Now if you require a /\/\ Voting Comparator it's the Model # T1786A and requires the following options:
1 C175 Tone Keying Module
2 C178 Signal Quality Module
1 C235 Tone Priority Module (Provides Console Priority for Dispatch)
1 C366ADSP Roofing Filter (Prevents Down Voting at Co-located Tx Site)
The Spectra-TAC Voting Comparator can be mounted in the same 46" cabinet as the MTR2000 Base Station Repeater. The X269 Option for Spectra-TAC Status Tone would need to be added to the MTR2000 station
so it functions as one of the Satellite Voting Receivers.
You would be required to order at least one MTR2000 Satellite Receivers Model # T5731 /\/\ Account Rep or T5769 Independent /\/\ Dealership and select another high location site for receive signal only to fill in for the poor system coverage. These would be the options you need for the MTR2000 Receivers:
X52 30" Cabinet
--- OR ---
X741 30" Open Relay Rack
X265 External Preselector
X269 Spectra-TAC Status Encoder
X319 VHF Operation
X597 Conventional Analog
As you would ADD MTR2000 Satellite Receivers to the Voting system, you'll be required to purchase additional C178 TRN6091D Signal Quality Modules SQMs for the Spectra-TAC Voting Comparator.
TAC stands for Total Area Coverage.
Dan
All of these Models and Option numbers are current and in the /\/\ Price Pages or through Motorola On-Line.
The MTR2000 Base Station Repeaters are sold as a Model T5544 /\/\ Account Rep or T5766 Independent /\/\ Dealership (but they are the same unit). These units are Tone Remote Control ONLY for the Console requirements. The MTR2000 can be set-up as 12.5 kHz or 25 kHz Channel ANALOG Spacing. The MTR2000 Product Line is NOT compatible or upgradable with the new Digital APCO P25 Standard Products. Here are the options you should have on the order form:
X182 VHF Duplexers (Minimum 1.5 MHz Frequency Tx to Rx Separation)
X265 External Preselector (for a High RF Enviroment Site)
X308 46" Cabinet (for the Peripheral Equipment in the cabinet)
X319 VHF Operation
X580 Repeater Operation
X597 Convention Analog
X676 External Double Circulator (Helps prevent Intermodulation mixes)
X 100 Watt RF Power Amplifier (CLN1225)
100 Feet 1/2" 50 Ohm Heliax RF Feedline Antenna Cable with "N" Type Connectors, RF Surge Adaptor and +5.2 dB Fiberglass Vertical Antenna.
*Here's* where I disagree that you need Battery Back-Up for the station.
Generally all large hospitals and medical complexes have Emergency Generators supplying Primary Power to the critical areas in the buildings including the elevators and radio equipment rooms. Tou can order the Battery Back-Up DC Supply and required Batteries but it will be redundant to the hospital's emergency power system.
Now if you require a /\/\ Voting Comparator it's the Model # T1786A and requires the following options:
1 C175 Tone Keying Module
2 C178 Signal Quality Module
1 C235 Tone Priority Module (Provides Console Priority for Dispatch)
1 C366ADSP Roofing Filter (Prevents Down Voting at Co-located Tx Site)
The Spectra-TAC Voting Comparator can be mounted in the same 46" cabinet as the MTR2000 Base Station Repeater. The X269 Option for Spectra-TAC Status Tone would need to be added to the MTR2000 station
so it functions as one of the Satellite Voting Receivers.
You would be required to order at least one MTR2000 Satellite Receivers Model # T5731 /\/\ Account Rep or T5769 Independent /\/\ Dealership and select another high location site for receive signal only to fill in for the poor system coverage. These would be the options you need for the MTR2000 Receivers:
X52 30" Cabinet
--- OR ---
X741 30" Open Relay Rack
X265 External Preselector
X269 Spectra-TAC Status Encoder
X319 VHF Operation
X597 Conventional Analog
As you would ADD MTR2000 Satellite Receivers to the Voting system, you'll be required to purchase additional C178 TRN6091D Signal Quality Modules SQMs for the Spectra-TAC Voting Comparator.
TAC stands for Total Area Coverage.
Dan
All of these Models and Option numbers are current and in the /\/\ Price Pages or through Motorola On-Line.
Re: VHF MTR2000 Base Station Repeater
BINGO! Redundency is key. What happens when there is a problem and the auto-start generator doesn't. There will be a downtime while the engineering guys go nuts trying to fix it. And for god's sake, if your going to be spending 10 grand on all of this, what is another few hundred for a nice power supply with battery backup?Dan562 wrote: *Here's* where I disagree that you need Battery Back-Up for the station.
Generally all large hospitals and medical complexes have Emergency Generators supplying Primary Power to the critical areas in the buildings including the elevators and radio equipment rooms. Tou can order the Battery Back-Up DC Supply and required Batteries but it will be redundant to the hospital's emergency power system.
"I'll eat you like a plate of bacon and eggs in the morning. "
- Some loser on rr.com
eBay at it's finest:
Me: "What exactly is a 900Mhz UHF CB?"
Them: "A very nice CB at 900Mhz speed!"
- Some loser on rr.com
eBay at it's finest:
Me: "What exactly is a 900Mhz UHF CB?"
Them: "A very nice CB at 900Mhz speed!"
-
psapengineer
- Posts: 175
- Joined: Thu Oct 07, 2004 10:00 am
Why Battery Backup ?
Here's why we use battery backup in addition to generator backup for stations that do alerting:
In the 1 in 1 million chance a car strike a power pole and the generator fails to start we can still alert the aid and fire crews. We also don't want to have to explain to our Board or the Media why a page didn't go out due to a lack of power.
It also allows me to do generator testing (where we drop power before re-applying power) without having to clear the test with the dispatcher (to confirm there are no alerts pending).
If the power source the station will be plugged into is a generator backed "UPS" then of course we don't use battery.
We're more casual about power for stations that don't provide alerting services.
Good Luck, Bob
In the 1 in 1 million chance a car strike a power pole and the generator fails to start we can still alert the aid and fire crews. We also don't want to have to explain to our Board or the Media why a page didn't go out due to a lack of power.
It also allows me to do generator testing (where we drop power before re-applying power) without having to clear the test with the dispatcher (to confirm there are no alerts pending).
If the power source the station will be plugged into is a generator backed "UPS" then of course we don't use battery.
We're more casual about power for stations that don't provide alerting services.
Good Luck, Bob
Well said. The battery backup's job is to cover the time gap between power failure and generator start. There is sometimes 30 seconds before power is restored on some systems- especially those with a lack of maintenance.
A pair of Optimas or other deep-cycle batteries will run most sites longer than you'd think. When it comes down to it, most power failures are less than 15 minutes.
A pair of Optimas or other deep-cycle batteries will run most sites longer than you'd think. When it comes down to it, most power failures are less than 15 minutes.
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CuriousGeorge
- Posts: 124
- Joined: Wed Oct 16, 2002 6:22 pm
First - thanks to everyone for your comments.
The comments about the battery backup were good to have. It was something I had thought of but was not included in any of the quotes I've gotten so far.
For what it's worth, the repeater will be hardwired to the dispatch center's Zetron console system (same building) so the control station issue is not a concern. Based on the terrain, there is a spot where an aux. receiver would be nice to have but its definately not in the budget this year so no voter, etc. in the picture for now.
But now for some followup questions...
1. Anybody have URLs to spec sheets for the GR500 and GR1225? I was already able to get one for the MTR2000 courtesy of Google and Motorola.
2. Hopefully #1 above will help me convince others that the GR500 and GR1225 are not the right solution for us. That was my initial impression not being a radio expert and I was a little surprised to get them as the recommend solution to our needs as opposed to a fallback solution when we tell the vendor we need to be more budget conscious. We're a volunteer organization with a small budget that's already stretched thin -- I'm sure nobody else here can picture that. <G>
Anyway, if we had to go with one of those (GR500/GR1225) for now, which one and why?
3. The MTR2000 quote I have pretty much matches Dan's part list with the substitution of 7/8" Heliax and a 30" cabinet, and no circulator. The two GR repeater quotes are similar to each other spec'ing 3dB antenna and either 1/2" Heliax or LMR400-FR cable. If we have to compromise to get up and running in the short term, any suggestions?
For example, substituting different feedlines -- Would using the 7/8" connected to a GR1225 improve the GR1225's performance relative to using the 1/2" over an 100 ft. run or is the cost difference not worth it? Would using LMR400 to the MTR2000 save some money without compromising the repeater?
I'm looking at this both in terms of performance now and flexibilty in the future. Maybe we put a GR500 in service now and then replace it with an MTR2000 in two years when more funding comes through and then use the GR500 for something else (mobile radio in a new vehicle, control station in headquarters, ...).
Right now, the quotes range from about $3500 (GR1225) to $8000 (MTR2000) so I have to figure out how to convince others within our organization (and our donors!) that we really need to spend the "extra" money as well as see what can be done to narrow the difference in the price range. This is just the equipment and installation -- still have to factor in service contracts, plus we need some new portables in addition to reprogramming what we already have. It all adds up.
- g
The comments about the battery backup were good to have. It was something I had thought of but was not included in any of the quotes I've gotten so far.
For what it's worth, the repeater will be hardwired to the dispatch center's Zetron console system (same building) so the control station issue is not a concern. Based on the terrain, there is a spot where an aux. receiver would be nice to have but its definately not in the budget this year so no voter, etc. in the picture for now.
But now for some followup questions...
1. Anybody have URLs to spec sheets for the GR500 and GR1225? I was already able to get one for the MTR2000 courtesy of Google and Motorola.
2. Hopefully #1 above will help me convince others that the GR500 and GR1225 are not the right solution for us. That was my initial impression not being a radio expert and I was a little surprised to get them as the recommend solution to our needs as opposed to a fallback solution when we tell the vendor we need to be more budget conscious. We're a volunteer organization with a small budget that's already stretched thin -- I'm sure nobody else here can picture that. <G>
Anyway, if we had to go with one of those (GR500/GR1225) for now, which one and why?
3. The MTR2000 quote I have pretty much matches Dan's part list with the substitution of 7/8" Heliax and a 30" cabinet, and no circulator. The two GR repeater quotes are similar to each other spec'ing 3dB antenna and either 1/2" Heliax or LMR400-FR cable. If we have to compromise to get up and running in the short term, any suggestions?
For example, substituting different feedlines -- Would using the 7/8" connected to a GR1225 improve the GR1225's performance relative to using the 1/2" over an 100 ft. run or is the cost difference not worth it? Would using LMR400 to the MTR2000 save some money without compromising the repeater?
I'm looking at this both in terms of performance now and flexibilty in the future. Maybe we put a GR500 in service now and then replace it with an MTR2000 in two years when more funding comes through and then use the GR500 for something else (mobile radio in a new vehicle, control station in headquarters, ...).
Right now, the quotes range from about $3500 (GR1225) to $8000 (MTR2000) so I have to figure out how to convince others within our organization (and our donors!) that we really need to spend the "extra" money as well as see what can be done to narrow the difference in the price range. This is just the equipment and installation -- still have to factor in service contracts, plus we need some new portables in addition to reprogramming what we already have. It all adds up.
- g
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thebigphish
- Posts: 1477
- Joined: Sat Nov 29, 2003 10:10 pm
- What radios do you own?: AM/FM
http://www.motorolaradio.com/products_r ... specs.htmlCuriousGeorge wrote:
1. Anybody have URLs to spec sheets for the GR500 and GR1225? I was already able to get one for the MTR2000 courtesy of Google and Motorola.
google mastery comes with time, grasshopper!
this should help.Coax loss per 100' on VHF High
LMR400: 1.54dB
1/2" Heliax: .83dB
7/8" Heliax: .45dB
As you can see, either of the heliax cables have negligable loss. 1.5dB on the LMR400 is by no means BAD either. However, many people have had complaints about RF issues to shielding seperation. I really don't have any specifics on that but I know someone will be able to shed some light on it. I don't think 1/2" heliax costs a LOT more than LMR400 so I would say that is your best bet. The 7/8"
is probably overkill and a waste of money.
LMR400: 1.54dB
1/2" Heliax: .83dB
7/8" Heliax: .45dB
As you can see, either of the heliax cables have negligable loss. 1.5dB on the LMR400 is by no means BAD either. However, many people have had complaints about RF issues to shielding seperation. I really don't have any specifics on that but I know someone will be able to shed some light on it. I don't think 1/2" heliax costs a LOT more than LMR400 so I would say that is your best bet. The 7/8"
is probably overkill and a waste of money.
"I'll eat you like a plate of bacon and eggs in the morning. "
- Some loser on rr.com
eBay at it's finest:
Me: "What exactly is a 900Mhz UHF CB?"
Them: "A very nice CB at 900Mhz speed!"
- Some loser on rr.com
eBay at it's finest:
Me: "What exactly is a 900Mhz UHF CB?"
Them: "A very nice CB at 900Mhz speed!"
Does Motorola even offer the GR500 anymore? It's just a couple of GM300 radios with a controller & heavier duty housing than a GR300. If you're getting a quote for one, make sure it's not just a dealer trying to get rid of 'old stock', maybe a demo unit or something. Unless they want to give it the appropriate price break & honor the warranty, of course.
Todd
Todd
No trees were harmed in the posting of this message...however an extraordinarily large number of electrons were horribly inconvenienced.
Welcome to the /\/\achine.
Welcome to the /\/\achine.
George, unfortunately, the bid process is the absolute worst way of trying to build a communcations system. Unless you have done your research beforehand and tell the communication companies exactly what you want, there are two things that happen...
1. someone gives you a high bid, with high end equipment you may not need and/or is more radio system than you require (this system will work, but due to its high pricetag, ends up being shredded by the accountant)
2. someone comes in with a low bid with equipment that may or may not do the job. accountants love these bids however and you may get stuck with a poorly functioning system just because the numbers on the last page were the lowest.
What you want to do is put out an RFP (Request for Proposal) and be prepared to pay for someone (or several someones) to come in and evaluate your needs and wants as to how your communications are supposed to work (don't tell them your budget). In the end you will get several proposals that will encompass your communication needs and you (and your accountants will be comparing Apples to Apples (you will also be able to get a feel for the various companies that respond to your request)
...Z
1. someone gives you a high bid, with high end equipment you may not need and/or is more radio system than you require (this system will work, but due to its high pricetag, ends up being shredded by the accountant)
2. someone comes in with a low bid with equipment that may or may not do the job. accountants love these bids however and you may get stuck with a poorly functioning system just because the numbers on the last page were the lowest.
What you want to do is put out an RFP (Request for Proposal) and be prepared to pay for someone (or several someones) to come in and evaluate your needs and wants as to how your communications are supposed to work (don't tell them your budget). In the end you will get several proposals that will encompass your communication needs and you (and your accountants will be comparing Apples to Apples (you will also be able to get a feel for the various companies that respond to your request)
...Z
[quote]1. someone gives you a high bid, with high end equipment you may not need and/or is more radio system than you require (this system will work, but due to its high pricetag, ends up being shredded by the accountant)
2. someone comes in with a low bid with equipment that may or may not do the job. accountants love these bids however and you may get stuck with a poorly functioning system just because the numbers on the last page were the lowest.[/quote]
Very well put Znarx !!!!
I wish more people would see it as a "system" and not as the lowest price el-cheapo stuff.
Matt
2. someone comes in with a low bid with equipment that may or may not do the job. accountants love these bids however and you may get stuck with a poorly functioning system just because the numbers on the last page were the lowest.[/quote]
Very well put Znarx !!!!
I wish more people would see it as a "system" and not as the lowest price el-cheapo stuff. Matt