I am looking for some suggestions on a new system i am working on. I have two condo's basically about 1000' apart. The first condo is 17 stories with 4 parking areas below. The second condo is only 8 stories with again 4 parking area's below. The parking area's are linked together from condo 1 to condo 2 which makes it easy to run cable to each parking lot. I am going to use a Mototrbo Repeater. My question is where would be a good place to put the repeater, what type of cable should i use, how many antenna's should i put in and what style antenna, should i quote a small bi directional amp from bird tech because of the 1000' run of cable from building 1 to 2 in the parking area's. Should i have 100 watt repeater vs 45-50 watts. Can someone give me some design idea's to do this system right.
thanks you in advance
john
Repeater System
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johnny1225
- Posts: 229
- Joined: Thu Jul 22, 2004 8:27 am
Re: Repeater System
Have you walked the buildings and demo'd Mototrbo in digital mode from the deepest parking garage to the highest floor?
Do the buildings have easy vertical chases to pull cable?
Are there electrical closets located in the lower garages? Are the garages underground?
Are there electrical closets / rooms on the roof or penthouse levels?
Option one: Place the repeater on the roof of the shorter building with a unity gain antenna on the roof.
Option two: Place the repeater on the roof or penthouse of the lower building feeding a splitter. One length of 1/2" Heliax goes to a unity gain antenna on the roof. The second length drops down the service chase to the second level underground parking lot to another unity gain antenna.
Option three: Place the repeater in the top level underground parking lot under the taller building with a three way splitter. One length of Heliax drops into a lower garage. The other two lengths go up the vertical chases to the 12th floor of the taller building, and 4th floor of the shorter hopefully into an accessible service closet.
Do the buildings have easy vertical chases to pull cable?
Are there electrical closets located in the lower garages? Are the garages underground?
Are there electrical closets / rooms on the roof or penthouse levels?
Option one: Place the repeater on the roof of the shorter building with a unity gain antenna on the roof.
Option two: Place the repeater on the roof or penthouse of the lower building feeding a splitter. One length of 1/2" Heliax goes to a unity gain antenna on the roof. The second length drops down the service chase to the second level underground parking lot to another unity gain antenna.
Option three: Place the repeater in the top level underground parking lot under the taller building with a three way splitter. One length of Heliax drops into a lower garage. The other two lengths go up the vertical chases to the 12th floor of the taller building, and 4th floor of the shorter hopefully into an accessible service closet.
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Tom in D.C.
- Posts: 3859
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Re: Repeater System
Option 4: What's wrong with having the company that sold you the radios give you some design help on the system you wish to install? Usually there is no substitute for experience, to paraphrase the old Latin saying.
Tom in D.C.
In 1920, the U.S. Post Office Department ruled
that children may not be sent by parcel post.
In 1920, the U.S. Post Office Department ruled
that children may not be sent by parcel post.
Re: Repeater System
I think he's doing the selling.
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johnny1225
- Posts: 229
- Joined: Thu Jul 22, 2004 8:27 am
Re: Repeater System
yes bill the 4 parking garages are underground, and yes they do have electrical rooms in the parking levels. The risers run from top to ground in both building so it is a pretty easy run. You think 1/2" heliax cable with what type of antenna's do you think. would LMR 400 cable be good enough or should i go with what you recommend.
thanks john
thanks john
Re: Repeater System
Hi Johnny. Got yerself a new project I see. Hoo boy - underground garages present their own form of heck, but nothing insurmountable. Obviously the homeowners association for the condos, or the building management company, have a limited budget. Mototrbo is a good choice for this application. If Canadian rules are like USian, you guys are on a short curve to go narrowband, and it's better to sell systems that go into the future than sell something that will need replacement shortly. So, good choice there. But, the antenna distribution system could be the budget buster. The more choices they have, and the more information you give them, the better compromise they can make for themselves. They'll go in with their eyes open knowing they are not going to cover every corner on the first attempt .... probably.
Yes, I would stay away from LMR cable and use 1/2" Heliax because of the long runs and high losses they'll experience. The first option I gave you is the cheapest, and it will probably give them 85% coverage of everywhere they want to talk. You should be able to get away with using LMR on that installation. The coverage may be good enough. Option 2 will guarantee some coverage into the basement garage but you won't know how much until after it's built, and I would strictly use Heliax to keep vswr and loss problems minimized. Option 3 is probably the worst and most ridiculously expensive option I gave you, but might give the most even coverage depending on how radio dark the buildings are. I don't know the building construction or how well UHF propagates in the living areas. One antenna above ground and one below may do it all just fine if the buildings are radio transparent. Most residential construction is light weight and fairly transparent as opposed to municipal buildings and hospitals. But, you're the guy on the ground.
I would offer them option 1 with Heliax which gives them a migration path to option 2. Or they could modify option 3 putting the repeater in the basement with one antenna up and one antenna down, with the system ready to add a third long line to the second building if necessary.
Yes, I would stay away from LMR cable and use 1/2" Heliax because of the long runs and high losses they'll experience. The first option I gave you is the cheapest, and it will probably give them 85% coverage of everywhere they want to talk. You should be able to get away with using LMR on that installation. The coverage may be good enough. Option 2 will guarantee some coverage into the basement garage but you won't know how much until after it's built, and I would strictly use Heliax to keep vswr and loss problems minimized. Option 3 is probably the worst and most ridiculously expensive option I gave you, but might give the most even coverage depending on how radio dark the buildings are. I don't know the building construction or how well UHF propagates in the living areas. One antenna above ground and one below may do it all just fine if the buildings are radio transparent. Most residential construction is light weight and fairly transparent as opposed to municipal buildings and hospitals. But, you're the guy on the ground.
I would offer them option 1 with Heliax which gives them a migration path to option 2. Or they could modify option 3 putting the repeater in the basement with one antenna up and one antenna down, with the system ready to add a third long line to the second building if necessary.
Re: Repeater System
I don't normally go against the grain of what Bill-G comes up with, but in this case I have to. In the years that the
LMR400 and other sizes have been attempted to be used in repeater service, most of them have had to go back in
a year or so and change out the cable to something that didn't use the aluminum foil and copper braid as a shield.
There have been numerous threads on many sites on the LMR type cable used in repeater or duplex service. The
cable has some impressive specs, but with time, it develops noise and desense in this kind of service. The complex
issue of noise being generated in the connection between the foil and the copper braid with just a small intrusion
of moisture has caused some of the better radio techs to spend weeks trying to resolve their system noise issues.
There are those that say LMR type coax works very well in repeater service. I know from some hands on time
working with this cable that it is not worth my double or even triple efforts to have to replace it. I don't want to
have to come back and explain to a customer, that his coax cable that I just put in a year ago is bad.
The choice of a "heliax" type cable is a much better, long term solution for repeater service. You don't have a
dis-similar metal issue to worry about. Do a clean install and weather seal all coax connectors, even though your
going to be inside a building. Water has a funny way of finding coax connectors, even inside a building.
Jim
LMR400 and other sizes have been attempted to be used in repeater service, most of them have had to go back in
a year or so and change out the cable to something that didn't use the aluminum foil and copper braid as a shield.
There have been numerous threads on many sites on the LMR type cable used in repeater or duplex service. The
cable has some impressive specs, but with time, it develops noise and desense in this kind of service. The complex
issue of noise being generated in the connection between the foil and the copper braid with just a small intrusion
of moisture has caused some of the better radio techs to spend weeks trying to resolve their system noise issues.
There are those that say LMR type coax works very well in repeater service. I know from some hands on time
working with this cable that it is not worth my double or even triple efforts to have to replace it. I don't want to
have to come back and explain to a customer, that his coax cable that I just put in a year ago is bad.
The choice of a "heliax" type cable is a much better, long term solution for repeater service. You don't have a
dis-similar metal issue to worry about. Do a clean install and weather seal all coax connectors, even though your
going to be inside a building. Water has a funny way of finding coax connectors, even inside a building.
Jim
Bill_G wrote:Hi Johnny. Got yerself a new project I see. Hoo boy - underground garages present their own form of heck, but nothing insurmountable. Obviously the homeowners association for the condos, or the building management company, have a limited budget.
Yes, I would stay away from LMR cable and use 1/2" Heliax because of the long runs and high losses they'll experience. The first option I gave you is the cheapest, and it will probably give them 85% coverage of everywhere they want to talk. You should be able to get away with using LMR on that installation.
Re: Repeater System
We're cool Jim. He needs to hear this. That's the beauty of grownups discussing the pros and cons of ideas. It's all done with respect and recognition of each others talents. It's wonderful thing. Please, by all means, state your thoughts. You do it well. As I told someone recently - take pride in your work, but don't invest your pride. This is humbleing work at times, and no one knows everything about all things. I'm glad to put my ideas out there, and welcome others questions and insights.
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johnny1225
- Posts: 229
- Joined: Thu Jul 22, 2004 8:27 am
Re: Repeater System
thanks you guys for all your help. I appreciate it. One more question, what would be a good unity antenna to use. I usually use sinclair SLR 301's. Do you have a better recommendation for me.
thanks again bill and jim
john
thanks again bill and jim
john
Re: Repeater System
The Telewave 450D series folded dipole is an excellent building penetrator. For your application, a single element is all that is required on the roof.
http://www.telewave.com/pdf/TWDS-7033.pdf
Indoors, because of materials clearance issues, it may be better to use a salt shaker mobile antenna like the Antennex TRA4503P with a ground plane.
http://www.lairdtech.com/DownloadAsset.aspx?id=2496
http://www.telewave.com/pdf/TWDS-7033.pdf
Indoors, because of materials clearance issues, it may be better to use a salt shaker mobile antenna like the Antennex TRA4503P with a ground plane.
http://www.lairdtech.com/DownloadAsset.aspx?id=2496
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johnny1225
- Posts: 229
- Joined: Thu Jul 22, 2004 8:27 am
Re: Repeater System
thanks bill i am going to give them a try
best regards,,
johnny
best regards,,
johnny
Re: Repeater System
(insert tongue in cheek here) Yes, use a 100-watt repeater, as long as you are running 100-watt mobiles.johnny1225 wrote: Should i have 100 watt repeater vs 45-50 watts.
In reality, as this appears to be an in-building system, I suspect that you are running portables only. Generally, for a balanced system (equal talk out and talk in range) there is no reason to run more power on the repeater than your mobiles/portables are running (assuming equal losses in the RX/TX paths of your antenna/multicoupling system). If you are only running 4-watt portables, and your losses are equally in your RX/TX paths of the multicoupling/antenna system, you really will not see any benefit to go over 4 to 5 watts on your repeater output.