GMRS setup info/advice

[Guest JEH]

Hello, i am looking to get into the GMRS world and would like some input and advice on the how to's and what not's to achieve my goal.  here's what im after, i am trying to connect 2 locations via Radio for emergency purposes.  After Hurricane Helene hit us our entire AO was without comms for several days and i want to ensure that this does not happen again.  said locations are almost 20 miles apart in a straight line with location A being roughly 140ft higher in elevation than B.  mostly woodland with several open fields in between, all rural land in S.E. Georgia.  There are no know repeater locations near nor between location A/B according to the map on here.  i was looking at the MIDLAND MXT500 Base Station Radio or the BTECH GMRS-50V2 50W 256 for both locations along with a few handhelds to use within each locations immediate area.  i know i will need an antenna for each location and im thinking that a 30ft pole for each site will be suffice but im just not sure what kind.  Also, i may also consider adding a repeater at location A down the road.   i am not able to go "no limit" budget but also do not want to go the cheapest route.  Any and all advice would be greatly appreciated! 

[WSIK532]

Hi,

Both choices are good ones, I would say the Kind of antenna is very important. Look up GMRS antennas on amazon, also look at YouTube for some tips as well. I sure some of the other Radio Experts (in my opinion, Great people by BTW) on here will give more feedback to this question, but I would say a repeater even if it's the portable one: Amazon.com: Retevis RT97S GMRS Repeater, RT97 Upgraded Version, Radio Repeater, Full Duplex Long Range, Compatible with Raspberry Pi, Portable, LCD Screen(1 Pack) : Electronics

I understand you are budgeting things out.  just put this on the list this can maybe be deployed in the event of a storm and then you can cover the 20-mile gap.

I'm just thinking of Quick deployment scenarios.  

I'm also New to GMRS.

 

 

[WSHH887]

Pretty new here as well.  If you are looking for a lot of good information, and not a little entertainment go here.

https://www.youtube.com/@TheNotaRubicon

[dosw]

RF line of sight could be a problem, depending on how high you can realistically mount your antennas. An antenna mast with mounting hardware could easily set you back a couple hundred, to get your masts up 30 feet. On the other hand, mounting each antenna fifteen feet up on the roof, with one property 140 feet above the other property, could get you right around 20 miles. This is good news because it also means RF line of sight roof-top to roof-top is something you can verify with a couple of inexpensive handheld radios.

 

So before buying nice radios, and before buying masts and antennas, buy a couple cheap GMRS handhelds for $30 each. Each of you stand on your roof. And try to talk to each other. If you get nothing, no static, no roger beeps, nothing, you're just out of luck. Those wooded areas between you are attenuating too much of your signal. On the other hand, if you're able to break squelch and hear each other a little, you can proceed.

 

Now assume that you were able to break squelch for each other. What next? Each of you get a 25w to 50w radio, however many feet of LMR400 cable you each need, lightning arrestors, some fittings, and appropriate mounting hardware for the roof. Get a couple of  antenna such as the Comet GP6NC GMRS antenna. Oh, and get 13.8v power supplies.

Adding it all up you'll be spending around $525 to $725 each.

 

As for repeaters; a repeater is useful if it can be higher than the other radios, and/or positioned somewhere between the other radios. It's useless to put a repeater on your roof, if the goal is just to extend range from your roof to the other person's roof. A repeater won't be giving you more range. What a repeater does is it allows one radio talking to the repeater to hear another radio talking to the repeater. If A and B cannot hear each other, but A can hear C, and B can hear C, then putting a repeater at position C will allow A and B to hear each other by talking through C. 

 

Another thing to do is to investigate what ham repeaters are in your area. If there are no GMRS repeaters, you may discover there *are* ham repeaters. Then you get licensed for whatever type of repeater exists in your area. If you find GMRS repeaters, great, get your GMRS license. If you find ham repeaters, you and the other party need to study for a couple weeks and get your ham licenses. If you are fortunate enough that there are good repeaters in your area (ham or gmrs), then you don't need to spend 500-700 each. You can each get a $30 radio that is made for the service type you're getting licensed in, and talk through the repeater.

In my area there are about seven or eight pretty good GMRS repeaters. But there are also at least 25 very good 2m or 70cm amateur/ham repeaters. If that ratio holds true elsewhere, even if you don't have a GMRS repeater in your area, you may find there are one or more decent ham repeaters.

[Majik]

5 hours ago, Guest JEH said:

i was looking at the MIDLAND MXT500 Base Station Radio or the BTECH GMRS-50V2 50W 256 for both locations along with a few handhelds to use within each locations immediate area.  

The Midland is a solid unit for GMRS, but it’s quite expensive. It also ONLY does GMRS – no VHF/UHF scanning. 
 

That B-TECH is far less expensive, but I’ve read reports that it’s a bit quirky, sometimes noisy, and the volume is only accessible via menus. But it has fully integrated mic controls and can scan VHF/UHF. 
 

For my mobile station, I eventually settled on the AnyTone 778II (w VOX). It’s only 25W, but sounds amazing, scans VHF/UHF, and seems to have plenty of power to throw signal where I need it. AnyTone is also highly regarded in the budget mobile/base radio segment. See if they have a 50W radio that meets your needs, but I’m betting 25W would serve you well with the right antenna and mount location. 

[LeoG]

I could do a Radio Mobile calculation to let you know if you have line of site or not.  I would need pretty specific gps location to do so.

[BoxCar]

Scadacore will let you model the RF path between your two sites by showing the terrain and earth curvature you need to factor in for antenna height. As far as equipment, the three most important things are: 1) Antenna; 2) Height above ground (AGL) at both sites; 3) radio. If you don't have a clear path, no antenna or radio will work at GMRS frequencies as the signal travels about 15% further than the horizon. Power just means there is more signal in the area, not more distance. The 20 mile distance you estimate would be adequately served with a 25W radio in most instances. Personally, I would choose an Anytone radio over the two you mention as their price/performance is on a par with much more expensive units from other Chinese manufactures. 

 

RF Line of Sight - SCADACore

[WRXB215]

That 778 is the one I have. Nice radio for the price. It can transmit on 2m, 70cm, and GMRS if you pick the right band range.

Yes, I know, I'm slapping my own hand for saying it.

[WSIK532]

9 hours ago, Guest JEH said:

Hello, i am looking to get into the GMRS world and would like some input and advice on the how to's and what not's to achieve my goal.  here's what im after, i am trying to connect 2 locations via Radio for emergency purposes.  After Hurricane Helene hit us our entire AO was without comms for several days and i want to ensure that this does not happen again.  said locations are almost 20 miles apart in a straight line with location A being roughly 140ft higher in elevation than B.  mostly woodland with several open fields in between, all rural land in S.E. Georgia.  There are no know repeater locations near nor between location A/B according to the map on here.  i was looking at the MIDLAND MXT500 Base Station Radio or the BTECH GMRS-50V2 50W 256 for both locations along with a few handhelds to use within each locations immediate area.  i know i will need an antenna for each location and im thinking that a 30ft pole for each site will be suffice but im just not sure what kind.  Also, i may also consider adding a repeater at location A down the road.   i am not able to go "no limit" budget but also do not want to go the cheapest route.  Any and all advice would be greatly appreciated! 

See, I told you would get a lot of assistance from the people on here! 

[GreggInFL]

13 hours ago, dosw said:

So before buying nice radios, and before buying masts and antennas, buy a couple cheap GMRS handhelds for $30 each. Each of you stand on your roof. And try to talk to each other. If you get nothing, no static, no roger beeps, nothing, you're just out of luck. Those wooded areas between you are attenuating too much of your signal. On the other hand, if you're able to break squelch and hear each other a little, you can proceed.

Yeah, this. I once hit a repeater that was ~30 miles away by standing on top of a parking garage -- with an $18 handheld.

[WRTC928]

I have gotten 20 miles HT-to-HT once when both of us were on elevated terrain features. Given the 140' elevation difference, you might be able to do it. The best-case scenario is if both stations are on higher elevations than everything in between, but one station higher than the other does improve your chances of getting a clear line of sight. You'll have to consider gain when you select your base station antennas. The more gain an antenna has, the "flatter" its signal, and it's possible to make the signal so flat it passes over the station at a lower elevation. There are some folks on here who know more about that than I do and might be able to help you figure out if that's going to be an issue. Generally speaking, more gain = more distance, so you'll have to balance the two factors.

[dosw]

12 minutes ago, WRTC928 said:

I have gotten 20 miles HT-to-HT once when both of us were on elevated terrain features. Given the 140' elevation difference, you might be able to do it. The best-case scenario is if both stations are on higher elevations than everything in between, but one station higher than the other does improve your chances of getting a clear line of sight. You'll have to consider gain when you select your base station antennas. The more gain an antenna has, the "flatter" its signal, and it's possible to make the signal so flat it passes over the station at a lower elevation. There are some folks on here who know more about that than I do and might be able to help you figure out if that's going to be an issue. Generally speaking, more gain = more distance, so you'll have to balance the two factors.

It would be very hard to find a mass produced antenna with so much gain that it would cast its signal too high or too low for another antenna at a 140 foot offset 20 miles away. That's 0.00135%, or 0.076 degrees. That level of focus of signal is in the realm of laser beams, or antennas for communicating with equipment on the moon. Another way of looking at it is that a boat's radar, which is designed to have good resolution characteristics, could merge two objects into one if they're less than 300 feet apart at 20 miles.