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Taking Suggestions: Repeater for 1/4 square mile campus

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I am a noob to a lot of amateur radio and I am investigating and planning a repeater setup to be installed in my workplace. We are on a hospital campus in Chicago, IL and have many tall buildings around us. Thus our 30-50 Kenwood TK-3160 and TK-3360's are not powerful enough to penetrate the many concrete walls to always provide the best reception on all ends of the building and across campus.

I wanted to see what suggestions the community has for a cost effective repeater setup for a scenario where we would be repeating 3-5 channels of uhf traffic. There is one other repeater on campus but we do not have access or permission to mess with it.

A functionality that we would like to have is to also repeat the NOAA weather channel for our area to a uhf channel for our handhelds to tune into. I believe NOAA broadcasts on vhf if I remember correctly. So some suggestions with the functionality would be nice too!

Since the 3 channels we are using just for our building are on the same frequency for transmitting and receiving, do we need to have a separate channel for each direction?

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Repeaters utilize 2 frequencies, one for tx and one for rx, typically separated by 5MHz.  You would need to purchase a duplexer (and also a combiner if you opted for multiple repeaters on 1 antenna.)  Don't go cheap on your antenna. This is where you get what you pay for and could mean the difference of hitting said repeater on the far side of an outlying building or being deaf to it.  A commscope DB40* series antenna is what I recommend. 

Officially, your FCC license would need to be set up for repeater frequency pair(s), but you theorectically could do it with your currently authorized frequencies but you would lose functionality on those frequencies unless you utilize different tones to have your system discriminate between repeater traffic and talk around.  

Your request for NOAA WX channel is a different beast. First and foremost, I am not sure of the legality of it.  Rebroadcasting of NOAA would require permission from either the FCC, NOAA, or both.  They are finicky about that and have a whole bunch of legal and lawyer mumbo jumbo that comes with it.  If approved as needed, you would either have to have a designated crossband repeater/radio setup rated for 100% duty use since the weather is broadcasted 24/7; and utilize one of your licensed frequencies, or you would need to buy dual band radios (vhf/uhf).  The dual band radios would be my personal choice if that was something I "had to have".  It would make it so the FCC and NOAA didn't get involved. It would just be a simple programming of the radio to add in the 7 frequencies and make them no-tx radio channels.  Another option would possibly be something like a phone patch on said repeater.  You would dial in on your DTMF keypad (if you have one on radio) a certain key sequence and turn on the weather audio.  When done, dial in a different key sequence to turn it off.  The caveot of that is everyone on that channel would hear it being broadcasted every time anyone keyed in the weather.  This possible idea also requires the same permissions as the first suggestion.

However, wiith technology advancing, smart phones have realtime NOAA alerts based on your gps location as well as the ability to look at radar/forecasts. I personally wouldn't bother with trying to get NOAA weather on UHF only radios.  
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