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50W vs 100W Repeater 10 Miles Radius Handheld vs Mobile Two Way Radio

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aaronhorowitz

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I'm trying to set up a UHF dispatching system for a non-profit emergency service in an urban setting. There will be many buildings and I will do my best to find the tallest building to install the repeater on.

I was considering buying either VXR 7000 (50Watts) or VXR 9000 (100 Watts). The area I need the best reception is in a 10 miles radius and I have heard the 50 Watt repeater is sufficient. Nevertheless, I was recommended to use mobile radios because of portable (handheld) radios have lower watts (range). Thus I was hoping that by investing more on the VXR 9000 with 100 Watts I would instead be able to purchase a 5 Watt Handheld operating within the 10 miles radius. Considering the cost of mobile radios and the need to have to install them in cars, handhelds would save us significant headache.

In an urban setting with a lot buildings, if I find a rooftop in one of the taller buildings, will a 50 Watt repeater be sufficient? I was looking at KENWOOD TK313 as the handheld. I've heard great reviews.

I would appreciate your advice.
 

Thunderknight

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If you are saying you think you can get away with portables by using a higher wattage repeater, it doesn't work that way. The limiting factor will be the lower transmit power of the portable, this is called talk-back limited.
Depending on the feedline length from the antenna to the repeater, a tower top amp (TTA) can help some. But you may need to look into voting receivers in multiple locations to pick up the talkback difference from the lower power portables.
A key question here is do you need coverage in the buildings or only outside? Inside buildings in an urban setting can add a lot of extra losses.
 

rapidcharger

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I was looking at KENWOOD TK313 as the handheld. I've heard great reviews.

I would appreciate your advice.
tk313? Can you double check that model number. I am unfamilar with any kenwood with that model number although there is a protalk radio that is 3130 and 3131. Those kenwood protalks with that model number are only 1 watt I think. Not even sure if they are repeater capable.

As for the portables vs mobiles, the good news is you can try it before you buy it. Call a dealer that rents radios or loans them out for demos and do some coverage tests ahead of time. It's impossible for any of us to say if you'll have portable coverage. As has pointed out in the previous reply, getting a signal to the portables and getting a signal from the portables to the repeater are two entirely different things. The output of the repeater makes no difference on the signals received from the portables.
 
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aaronhorowitz

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So let me get this clear,

If a repeater has a 50W ( supposedly 1 Watt=1 Mile) I know that's depends on many actors (buildings, elevation...) and I have a handheld that has 1 watt (1 mile+ miles). Does it mean that the operational zone is determined by the device with the lower watt? That the 50W repeater will not pick up all signals that are in it's coverage radius? I think this is what I need to know. Does the talk zone of two way devices begin at the point where one's transmission range meets the other's reception range? In other words, if 1 device has 5 miles and the other 2 miles transmit/receive radius, I would effectively need to be within a two mile radius to communicate? Thus, radius is determined by the lower Watt device?


THANKS!
 

kayn1n32008

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regardless of any advice you receive here, you need to call some professionals. Step one is using software to plot predicted coverage of a given site. You need to make sure the site you pick will give you the desired coverage. This software is ver complex to use. It needs to be done by someone who knows what they are doing. Just because the building is tall does not mean it will provide adequate coverage.

Setting up a repeater is not as simple as it looks. There are many steps, and parts and pieces, from duplexer, circulator, polyphaser, proper double sheided jumpers, service monitor to set levels, battery plant for when, not if, the power fails, power supply, the list goes on.

As far as dropping a repeater on a building? That WILL require a contract with the building owner, who will most likely have a list of technical requirements you need to meet, one of these WILL be insurance. Another will be a RF study, to ensure you, not only do not cause interference to others, but also so other Colo's do not cause you interference.

This is not a small undertaking, and needs to be done right. Hire professionals who know what they are doing. This is not something an inexperienced person should be doing.
 
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BlueDevil

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Invest in a good antenna for your use and place it strategically. This is a much better investment with more bang for the buck versus more wattage!
 
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regardless of any advice you receive here, you need to call some professionals. Step one is using software to plot predicted coverage of a given site. You need to make sure the site you pick will give you the desired coverage. This software is ver complex to use. It needs to be done by someone who knows what they are doing. Just because the building is tall does not mean it will provide adequate coverage.

Setting up a repeater is not as simple as it looks. There are many steps, and parts and pieces, from duplexer, circulator, polyphaser, proper double sheided jumpers, service monitor to set levels, battery plant for when, not if, the power fails, power supply, the list goes on.

As far as dropping a repeater on a building? That WILL require a contract with the building owner, who will most likely have a list of technical requirements you need to meet, one of these WILL be insurance. Another will be a RF study, to ensure you, not only do not cause interference to others, but also so other Colo's do not cause you interference.

This is not a small undertaking, and needs to be done right. Hire professionals who know what they are doing. This is not something an inexperienced person should be doing.
I am sorry, but this response was and is completely off subject of the original question from "aaronhorowitz". He wasn't ask about ANYTHING you mentioned except about building height.. He didn't ask if the software is (ver) complex or if a building will require a contract or the parts of a repeater site. He asked about coverage and which wattage repeater he should get. Your advise to get a professional to do it, is basically telling him, he isn't allowed to learn it him self. Which maybe he wants to, which is why he is asking. A ham operator learning to do something doesn't just call a "professional" because he/she doesn't know how to do something, how is that person supposed to learn and educate themselves? The last thing I will mention is how insulting and ignorant your final paragraph was, at least I took offense to it, as you are insinuating it won't be done right with out "professionals". I have seen lots of stuff done better by non-"professionals" then "professionals" who DON'T know about what they are doing.

That is all, have a good day.
 

SteveC0625

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regardless of any advice you receive here, you need to call some professionals. Step one is using software to plot predicted coverage of a given site. You need to make sure the site you pick will give you the desired coverage. This software is ver complex to use. It needs to be done by someone who knows what they are doing. Just because the building is tall does not mean it will provide adequate coverage.

Setting up a repeater is not as simple as it looks. There are many steps, and parts and pieces, from duplexer, circulator, polyphaser, proper double sheided jumpers, service monitor to set levels, battery plant for when, not if, the power fails, power supply, the list goes on.

As far as dropping a repeater on a building? That WILL require a contract with the building owner, who will most likely have a list of technical requirements you need to meet, one of these WILL be insurance. Another will be a RF study, to ensure you, not only do not cause interference to others, but also so other Colo's do not cause you interference.

This is not a small undertaking, and needs to be done right. Hire professionals who know what they are doing. This is not something an inexperienced person should be doing.
Well said. There is a lot of good info to be gleaned from these forums, but there comes a point when hiring a pro becomes the best move. High power public safety communications in an urban environment need to be designed by someone who is knowledgeable and experienced with a proven track record of success.

I applaud folks that want to learn more about these things. It better prepares one to sit at the table and explain your needs to a pro.
 

prcguy

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No reason to go 100w with what you are proposing and antenna height will do you more good than power. I have been a commercial repeater owner/operator for over 30yrs and have installed everything from 2w repeaters on low buildings to 100w+ systems on 5,700ft mountain tops in some of the worst RF environments on the planet.

When you get above the 25-30w range duplexer isolation requirements become more difficult and expensive. If the repeater is going in an area free of any other radio systems in the same band you might get away with a mobile notch only duplexer and a 30w repeater. More power will require a much more expensive pass/notch duplexer, larger power supply, etc.

Two way transmission is reciprocal, so a 100w repeater will be heard slightly farther than a 30 or 50w repeater but at some point the repeater will be heard just fine at some distance but 5w handhelds will not access the repeater with enough useful signal.

Don't know who mentioned the silly 1w per mile theory but its not a theory. 1w line of sight on a pair of UHF handhelds with 1/4 wave duck antennas can talk upwards of 300mi line of sight like ground to space with no ground bounce and multipath cancellation. Local terrain is what determines the range limits and more power will help but at some point if 50w doesn't make it 1000w will not.

My suggestion is find the highest building or tower in your area and a real 10dBD gain antenna, which will be around 20ft long with special mounting considerations. A 2 story building is not going to give you reliable 10mi range, you need to get the antenna up and in the clear of all surrounding buildings and terrain.

I live in an area with lots of hills and mountain ranges where we install repeaters for long distance use, so I have less experience with low level repeaters trying to get long range. I did have a 2w repeater on my 2 story building for awhile and I could access it in some directions out to 50mi from a mobile and maybe 10mi with a handheld but that was spotty and not reliable.

I believe a 10dB antenna with 30w repeater on say a 10 story building with flat surroundings should work very reliable to 30w mobile units with vehicle mounted antennas at 10mi. Handhelds maybe not so good past 5mi but there will be some areas that will work. The same repeater on a 30story building that's way above all obstacles and now the handhelds have a better chance of reliable 10mi communication through the repeater.

When you go with a higher end pass/notch duplexer with more than adequate tx/rx isolation, you can usually add a good quality preamp which can spiffy up the receive a bit for handhelds, but you must install one or two band pass cavities that gives you at least the same or more isolation between transmit and receive than the preamp has gain. Typical preamp gain is 15-18dB and more is just asking for trouble.

The cost of the components like a good pass/notch duplexer, Isolater, preamp, associated filtering, high quality cables, big antenna and the labor to tune and install all that can get quite expensive unless you have the knowledge and test equipment to do it yourself. A high performance repeater system is not a trivial matter and much more than a couple of mobile radios from Ebay slapped together with a controller and a cheap duplexer.
prcguy
 
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JnglMassiv

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I can't help but wonder if a dedicated system is the right choice here.
If the need for multiple receive site becomes apparent, the costs will skyrocket to jaw-dropping levels.
Add maintenance, rent and lease lines and the whole project could well implode upon its own expense weight. Hopefully, it won't be after all the expensive hardware is purchased.

How many portables/mobiles are expected to be deployed in this system?
Consider rent/leasing radios from a commercial provider and use their infrastructure.

It might be useful to further describe the particular nature of the OP's 'emergency service.'
For example, does this involve life-or-death type situations?
Is it possible for Bad Things to happen when a portable can't hit the repeater?

Anti-professional-services rants aside, this planning is highly situational and if a dedicated system is the clear solution, I don't think that at least some professional consulting is out of line.

I'd finally add that the 'x miles per watt' chestnut is straight up wrong. Even in an idealized environment, these things simply do not scale up in a linear fashion.

Fake edit: As so often the case, prcguy knows the score.
 

rapidcharger

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So let me get this clear,

If a repeater has a 50W ( supposedly 1 Watt=1 Mile) I know that's depends on many actors (buildings, elevation...) and I have a handheld that has 1 watt (1 mile+ miles). Does it mean that the operational zone is determined by the device with the lower watt? That the 50W repeater will not pick up all signals that are in it's coverage radius? I think this is what I need to know. Does the talk zone of two way devices begin at the point where one's transmission range meets the other's reception range? In other words, if 1 device has 5 miles and the other 2 miles transmit/receive radius, I would effectively need to be within a two mile radius to communicate? Thus, radius is determined by the lower Watt device?


THANKS!
Don't take this the wrong way Aaron, because we've all been there at some point, but you really do need some local help with this. Setting up a repeater properly can be complicated and we're starting with the basics.

Think of repeaters and radios as light bulbs. The more wattage, the more light they put out. If you have obstructions in the way, you may not see any light or you might see some of the light through or around the obstructions but it won't be as strong of a light. For example, you pull into the driveway of a house at night with the headlights of your car turned on. At the back of the house, someone standing there can see some light from your headlights on the other side of the house and tell that a car pulled up but the light is not bright enough to see what they are doing in the dark.

In this scenario, think of a repeater as another light fixture on top of the roof that is activated by your car headlights and then turns on, sending its own light down into the back yard. They're completely separate fixtures, the headlights of the car and the light on the roof of the house.

Similarly if you have a portable radio down the street and a repeater on top of a building, the emissions are separate. Like the magical light fixture on top of the house, that needs enough light hitting it to be activated, a repeater works in the same fashion. If you have a portable radio, you might be able to activate the repeater, especailly if there isn't much in the way. The output of the repeater has nothing to do with reception from the mobile units. The power output of the repeater only helps others receiving the signal from the repeater like that light fixture on the roof with higher wattage sending its light into the back yard. The 1 watt per mile is not a sound rule of thumb to use for designing a radio system.
 

kayn1n32008

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I am sorry, but this response was and is completely off subject of the original question from "aaronhorowitz". He wasn't ask about ANYTHING you mentioned except about building height.. He didn't ask if the software is (ver) complex or if a building will require a contract or the parts of a repeater site. He asked about coverage and which wattage repeater he should get.
Actually, the advice I gave him is SPOT ON. How about you go and re-read the OP. He is wanting to set up a DISPATCHING repeater for an EMERGENCY SERVICE agency. Setting up life safety Comms is NOT something a beginner should be doing. This can not be done by learning as you go. This needs to be done right the first time, by people that know what they are doing.

Your advise to get a professional to do it, is basically telling him, he isn't allowed to learn it him self. Which maybe he wants to, which is why he is asking.
Again this is going to be used, potentially, for life safety Comms, at least that is what I read between the lines in his post. So yes, he needs to have professionals in on this. This is not the time to be screwing around, figuring out how to put a repeater on the air, and making mistakes, when people are relying on it. It needs to be done right, and done right the first time. If he was putting up a ham repeater I would suggest finding an Elmer to help, the OP is putting up a repeater for an 'emergency service' entity, and again this is not the place to be learning through trial and error.

A ham operator learning to do something doesn't just call a "professional" because he/she doesn't know how to do something, how is that person supposed to learn and educate themselves?
Again, go back and read. The OP is NOT putting a ham repeater on the air. If he was, I would have given him much different advice. A ham repeater is not the same as putting up a repeater for first responders. I would encourage someone trying to put up a ham repeater. Please do not compare putting up a ham repeater to a dispatching repeater for first responders. And actually, I ask "professionals" lots of questions regarding ham radio, friends that have worked in the industry for decades, so yes even hams call professionals too.

The last thing I will mention is how insulting and ignorant your final paragraph was, at least I took offense to it, as you are insinuating it won't be done right with out "professionals". I have seen lots of stuff done better by non-"professionals" then "professionals" who DON'T know about what they are doing.
Well good thing you are not the OP.

I wholeheartedly agree, there are some "professionals" out there I would not let with in 20 miles of a ham repeater. They are out there. You need to make sure the "professionals" actually are competent, and that costs money, and time.

The OP states he is putting up a repeater for an emergency service agency. It is not the time to be dicking around learning that coax jumpers need to be double shielded, and not RG-58 70% braid. Or that a circulator is actually a good thing, or that maybe using 7/8" hard line makes better sense than using RG-213 to go from the duplexer to the antenna. Or that horizontal separation does not work nearly as good as vertical, or that a mobile duplexer is not going to work in a high RF environment. Things beginners can learn, but a repeater for emergency services is, IMHO, NOT the place to be learning by trial and error.

First responders need it to work the first time, not while a newbie learns through trial and error.

That is all, have a good day.
I was having a great day until seeing your post. While the OP was asking about building height, and power output, these are only a small part of the whole system, and IMHO, less important than selecting a site based on its predicted coverage, rather than just 'putting it on the tallest building I can get access to'. These details are rather important, and saying that this is the time to learn is opening up the OP to liability if the repeater is a cause of an incident.

I, even though I have built a few repeaters for amateur radio, who does not do this professionally, would NEVER attempt to design or implement, a repeater system for 'an emergency service' entity. I would insist that they need to hire the right people for the job, or rent time on an existing SMR, that has coverage where they need it.

You really need to understand that there is a time and a place to learn, and when it comes to putting up a repeater for emergency services, is NOT time and NOT the place to be learning the basics, or the details of putting a repeater on the air.

Good day to YOU sir.


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kayn1n32008

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Well said. There is a lot of good info to be gleaned from these forums, but there comes a point when hiring a pro becomes the best move. High power public safety communications in an urban environment need to be designed by someone who is knowledgeable and experienced with a proven track record of success.



I applaud folks that want to learn more about these things. It better prepares one to sit at the table and explain your needs to a pro.

SPOT ON. In all respects


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... Blah Blah Blah ...

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WOW. Let me say this. There is a HUUUGE difference between HIRING a professional and getting help from and having a professional ASSIST him. You seem to think, or at least implied that he should ONLY HIRE a professional to do everything for him, while numerous other people have said, to get a professional to assist and help him.
As for not a time for learning... you are mistaken. EVERY SINGLE THING you do in life, you should learn something from. Maybe he will learn something from this that he will be able to use every single day of his life, but you are trying to take that opportunity away from him.

Now, I am not saying nor have I ever said that this some small BS repeater. All I'm saying is that perhaps we shouldn't focus on him getting a pro to do it all, but rather HELP and ASSIST him. Even if it is him 25% and pro 75% doing the work. There is still much to be learned only doing 1/4 of the work as with anything.
 

kayn1n32008

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WOW. Let me say this. There is a HUUUGE difference between HIRING a professional and getting help from and having a professional ASSIST him. You seem to think, or at least implied that he should ONLY HIRE a professional to do everything for him, while numerous other people have said, to get a professional to assist and help him.

As for not a time for learning... you are mistaken. EVERY SINGLE THING you do in life, you should learn something from. Maybe he will learn something from this that he will be able to use every single day of his life, but you are trying to take that opportunity away from him.
I am assisting him. The advice I gave him IS sound. He is wanting to put up a repeater for EMERGENCY RESPONDERS. This is not the place to be screwing around. This is the time to educate some one on when it is time to take a back seat and get professional help.



Now, I am not saying nor have I ever said that this some small BS repeater. All I'm saying is that perhaps we shouldn't focus on him getting a pro to do it all, but rather HELP and ASSIST him. Even if it is him 25% and pro 75% doing the work. There is still much to be learned only doing 1/4 of the work as with anything.

You imply it. The OP demonstrated very limited knowledge about repeaters. He needs real help, professional help. Not every opinion from every Tom, D*ck and Harry on an internet message board.(there has been good advice here, and I am not in any way taking away from it, just the medium of communication)

The OP needs the assistance from people who can come in and asses the needs of the agency, asses potential sites, asses potential frequencies, and suggest a properly designed repeater system for the agency.


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prcguy

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If the repeater in question is actually depended on for emergency life saving or similar use I agree with anyone who recommended hiring a professional repeater service or radio shop to install and maintain the system.

I had contracts at one time for similar use repeaters and had to keep entire spare repeaters, antennas and all components to replace at a moments notice if there was a failure. It wasn't fun getting a phone call at 11pm and having to drive 50mi to the base of a mountain then drive 11mi up a treacherous dirt road in the rain to make repairs, but that's part of the business. Is the OP willing or able to maintain a repeater to that level?

Unless you have a contract with a radio shop or lease repeater time its not a good idea to take a DIY approach to emergency use or public service repeaters.
prcguy
 

12dbsinad

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Step number 1

Obtain a valid UHF license from the FCC. See what they will allow you for output power for the repeater. Then take that info to a radio shop. Or, have them just do everything. Reason being is, you just can't buy (legally) a 100watt repeater and just throw it on the air on whatever frequency gets approved. It all depends what the ERP is of the repeater output frequency and nowadays depending on the location can be relatively low.

Step number 2

You now need to calculate losses in duplexers, filtering, coax, and the gain of the antenna being used. Then you can calculate how much power you can put out from the PA. You may find that you cant even run a full 100watt repeater depending on how the above goes.
 

RadioGuy7268

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Step number 1

Obtain a valid UHF license from the FCC.
A lot of discussion and advice here, but the above advice is really the most useful. It all starts with a License, and depending on your area, a workable pair of clean & clear repeater frequencies might be quite difficult to get.

Knowing what's possible starts setting the parameters for what's practical. Contact a frequency coordinator and get an application form.

Good luck with it.
 
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