WRKI280

WQWU626
This is exactly what I need.
I ran a rough estimate, and I will cover most of the county in all directions using a 40' antenna.
 
Thank you

Here is where you can generate "maps" of your expected coverage based on the data you enter. This program will also consider topographic data. The 'green' areas are predicted HT @ 70% reliability, the 'yellow' areas are mobile coverage @ 70% reliability.
 
This was for a proposed repeater to be located near Schaumburg, IL. Unfortunately, after a detailed site survey we determined that there would be to much potential for conflict with all of the other repeaters on the 150' tower.
 
https://www.ve2dbe.com/rmonline_s.asp
 
 

Since UHF is essentially line-of-sight, you will often find you run into obstacles well before power becomes an issue.
 
BTW, if you really want a 50 watt transmitter be prepared to pay for it.. There is a huge difference between a 50 watt mobile and a repeater with the same power rating. The difference is duty cycle.  Your mobile will probably run around 0% much of the time, and then maybe 50% if you are in a conversation with one other station. However, the repeater can run at 100% duty cycle for long periods.  Try that with your mobile and you will fry/melt the finals.

There are some online programs to show you range. As said above height and antenna gain is everything. You can put 50 watts out on your garage roof and not talk as far as 5 watts on a 2500' mountain top.

I agree. I have a Ham Radio buddy that got permission, yes it's possible, several times to use his HT on a commercial jet flight. There was a bit of a pile up when you're talking 500 to 1000 miles radius from 30,000 feet on FM.

Also note that this is theoretical. I have a repeater mounted about 30' up. Going north, it loses signal about 3 miles out due to a large hill in that direction. To the south I easily get 8-10 miles reliably, and I've had reports of people reaching the repeater nearly 45 miles away from me, though only in particular spots. 
 
Terrain isn't the only issue that reduces range. Large buildings, high voltage transmission lines, and high RF environments tend to further diminish signals unless professional grade stuff is used. One thing I will say is if you get a flat pack duplexer, be sure to upgrade that first before switching to larger antennas. I found that each repeater I set up that started with flat pack duplexers, even the high quality ones like Celwave, often saw a 20-40% increase in range. I also found that by using 25W instead of 40W that the repeater seems to get the same range while being able to detect weaker signals from portables at longer distances.
 
 

As KB2ZTX mentioned the repeater alone will not get you into the net. You would also need one of these:
https://shop.mygmrs.com/collections/repeaters-and-accessories/products/repeater-linking-bundle
 
This unit connects your repeater to the internet and into the GMRS server, allowing you to operate on the network. Due to simplex (radio to radio) operations not needing a license, Rich does not want simplex nodes being set up everywhere that anyone can tie into which is why you would be required to have a repeater.
 
As for repeaters themselves, I prefer the Motorola GR1225/RKR1225 (Its the same unit however the RKR1225 is rack mountable) They go for about $300 used and seem to work well. 100% duty cycle on low power (25W.) The nice part is that the bundle kit above is plug and play, order the maxtrac cable, plug it into the back of the radio and your done.
 
If your somewhat serious about setting up a local repeater for friends or family, get a BP/BR duplexer(another $300ish plus tuning), good feedline($40-100 depending on length), and a fair 460-470 antenna($150), and mount it as high as you can. You should get some good coverage given the terrain you have, looks nearly flat farmland from google earth.
 
Setting up a repeater is an expense, however if there are no linked repeaters, and very few operating repeaters around, it is an option to do if you have the time and money to put into it.