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#1 Quarry Creek

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Posted 05 July 2018 - 02:34 PM

I've been trying to decide about GMRS for about a year now. I have two ranches in West Texas that are about 6 1/2 miles apart and in many areas cell phone is not reliable. I've had my ham license, but I can't legally use ham to conduct our family ranch activities.

 

I would also like to be able to communicate with my home in town which is about 9.5 miles.  I'm pretty sure I can't do this with just handhelds, but I plan to use the Midland MXT400 in by truck and set up a base at my home in town with another MXT400.  With my house being at least 20 ft high, I should be able to get an antennae around 40 ft. 

 

I've checked elevation on google earth, and my ranch has an elevation of approximately 80 ft higher than town (only 40 ft if the antenna is 40 ft), but there is a rise/hill about 10 feet higher that is about 1.5 miles from the ranch. Since I don't really have a lot of experience with UHF, I was wondering if it was likely that reliable communication would be possible between the mobile and base, with the base having a 40 ft antenna.

 

Ultimately, I'm thinking about putting a repeater at the ranch, which would allow a 40 ft antennae (20 ft. over existing structure) at that location. 

 

Any comments would be welcome.

 

Thanks - Karl


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#2 Jones

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Posted 05 July 2018 - 06:24 PM

Is that rise between your town house and ranch? If so, that might be a problem, but likely not.

 

I can get 15 miles from base to mobile anytime in the flat lands of southern Nebraska, so I doubt it will be a problem for you.

 

Installing a repeater on the high ground at your ranch would be ideal, since the base in town would easily bounce off that, and so could your family members working out on the ranch with handhelds.  Even non-family workers could use it, as long as they have individual GRMS licenses.

 

MTX 400 is a good radio, but don't use the cheap antenna they come packaged with.  Use high-quality antennas and coax cable.  Also, don't use the cigar-lighter plugs they come with.  Wire them up correctly, permanent installation style, and use a suitably rated power supply for the base.

 

On the mobile, (I assume pickup truck) drill a hole, and use an NMO mount antenna on the roof, as close to center as practical.  Don't skimp with a mag mount, or try to use an antenna mounted on the front fender, or you will be disappointed.  In my professional experience, a quarter wave on the roof, (which at UHF is about 6 inches tall) will out-perform a high-gain co-linear antenna on the front fender any day.


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#3 Elkhunter521

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Posted 06 July 2018 - 12:20 AM

I am using the midland mtx400. I agree completely with the previous response from (Jones). The mag mount is a mag mount. Im using a Browning br450. Trimed it with the SWR trim chart to 465 mhz .this is a nmo mointed antenna so drill the hole. It works well.
Be vewy vewy quiet.
I'm listening to my wadio!

#4 Quarry Creek

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Posted 06 July 2018 - 10:04 AM

Thanks for some confirmation. Yes, the 10 ft. rise is between the ranch and town, but that was measured at the ranch headquarters. There are higher places on the ranch that are high enough to be true line of sight. My real question was whether or not the 10 foot rise would be an issue.  From what you say, if I set up a repeater on the ranch it would pretty much eliminate any issues for me all over the ranch (its about 1000 acres which is not that big out here), so I would rarely be more than a mile from the repeater while on the ranch.  

 

The other ranch that is about 6 miles from mine is actually my brothers, but I lease and operate it. I might be inclined to set up a second repeater on it so we can use handhelds there as well.  I'm going to start with the base stations and some quality handhelds (not the "bubble pack"), but haven't really looked at specific ones - if anyone has any recommendations, I would appreciate input.

 

I had already decided on a 1/4 wave (6") antennae on my trucks - longer antennas don't do well in the brushy areas and driving under things that you do with a work truck on a ranch.  I've looked at several, but don't really know which ones are quality. If anyone has any brand/model suggestions to look at??

 

Certainly don't plan on skimping on antenna, radio, or mounts, but I do feel better about the potential seeing your replies and I think GMRS will work well for me. I'm the only one in my county that has a current GMRS license and the nearest repeater is about 60 miles away, so I shouldn't have much interference.  About a year ago I programmed the GMRS frequencies into a radio I use for scanning and have been of and on scanning and monitoring, and there is only occasional traffic, mostly vehicles passing through.  

 

Your reply (Jones) was almost exactly what I was planning on setting up, and your certainly right about the permanent wiring & antenna install.  Back in the 70's when we tried to use CB for this we did the same, but CB was only reliable for short range - 3 to 4 miles and wasn't very satisfactory. 

 

Thanks again for the insights.  Once I get everything setup and start using it I will definitely get back and post how it works out for this area.



#5 Jones

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Posted 06 July 2018 - 12:50 PM

As far as antenna brands, everybody has their favorite, but some of the more well respected brands are Laird, Pulse/Larsen, Maxrad, and the old standard, (yet highly over-rated, and over-priced) Motorola.

 

For your mobiles, get good quality NMO mounts with high-grade low-loss UHF rated coax.  For antennas, I would recommend Laird QW450 for chrome, or Laird QWB450 if you want them in Black.  The chrome ones are around $10 each, and the black ones are only a couple bucks more.  (This does not include the NMO mount cost.) 

At that low price, and considering the conditions you will be using them in, I would highly recommend buying a few spare antennas, and toss one in the glove box of each truck.  That way, when you go under some low brush and break one off, you can just screw another on and keep talking.  A pair of traditional CT pliers can quickly swap one of these out in the field in an emergency. (If you work with wire fencing on your ranch, then I'm sure you have a pair of CeeTees on your belt right now.)

 

For your repeater antenna, I would go with a Commscope DB404-B. You can use a lesser quality antenna for your base station in town, even a home-made J-pole will give good results, but for a repeater out in the middle of nowhere, you really should do it right once, instead of climbing back up to replace antennas every-other-year.  For coax cable on a repeater, use 7/8 inch Heliax.  For coax at the home base, use LMR-400. (or Heliax)

 

You will likely cover BOTH ranches if you can centrally locate a repeater on a Rohn HBX72 tower. That will get your center of radiation up at 75 feet above ground level, which would give reliable coverage to handhelds for about 10-12 Miles radius, and likely 25 miles from your mobiles.  If that won't cover your ground, then try a taller tower, or go with the idea of a separate repeater for each ranch, each on a shorter tower, and on separate channels, as they are too close to operate on the same channel pair without interference in the center. You could even use a third frequency to link the repeaters together if you needed, but now we're getting complicated.

 

I guess the next set of questions are: How far is it from the farthest edges of your properties? How tall and wide are these ranches? Can a single repeater be centrally located on a higher elevation area? ...and is there electricity available, or does this need to be a solar-powered repeater?



#6 Logan5

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Posted 06 July 2018 - 01:57 PM

do lots of testing with what you have on hand as well as some well thought out purchases. It is true that each potential radio site is different and you may be surprised at the results. Things to consider for testing, a push up pole, they make them 20 to 90 feet or so, buy what you think is best for you. a yagi antenna, can give you a huge advantage when  testing and setting things up, even if you end up with an omni in the end. I have used LMR400 and 600 only, both pretty flexible and easy to keep from damaging. good first timer cable. If money is no object, I also have a list. lol



#7 Quarry Creek

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Posted 06 July 2018 - 05:56 PM

Lots more good information for me.  I just realized I must have been looking at some old websites regarding height limitations on GMRS antennas. I'll be able to put them much higher than I thought, so that should eliminate the elevation issues I was looking at.  I will probably still look at putting up a repeater so I can use handhelds when we are out on 4-wheelers, tractors, and such.



#8 PastorGary

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Posted 06 July 2018 - 06:53 PM

199.9  feet unless you are within an FAA flight pattern for a local airport. See 47 CFR 95.317 for details and current restrictions.

https://www.ecfr.gov....1.1.5&rgn=div5

 


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#9 WRAF213

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Posted 06 July 2018 - 11:45 PM

If you slap up a good antenna (about 10dBi) at 30 feet or so, you should have good coverage of your city to full-power handhelds. 40W transmit power should keep your signal readable against the varying noise floors of portable environments. More height above ground will help the most, but your terrain isn't too bad.

 

I put together a rough coverage map with Radio Mobile, feeding it with data from your callsign and desired radio configuration. It's a KML file, Google Earth Pro should open it splendidly. In hindsight I failed to ensure the map had a >10 mile range (this one covers a 7.8 mile radius vertically); I'll re-run the coverage maps if it isn't sufficient. I can also run maps for repeater scenarios, PM me details (location, height, power, and antenna gain (If known)) and I'll get back when the maps finish generating.

 

I'd generally advise against using LMR400 for any repeater stuff, it can generate passive intermodulation interference from the aluminum foil shielding contacting the tinned copper braid; use hardline instead. Since you're not in an RF-busy area like a communications site, it's not going to be an issue unless you encounter some very specific interference.



#10 Jones

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Posted 07 July 2018 - 10:42 AM

The repeater antenna I recommended, the DB404-B has a gain of 5.9dBi, with no beam tilt.  That is a great antenna to use if you have it high in the air, and height always out-performs antenna gain.

 

A 10dBi gain antenna at 30 feet will do well in a situation like this, but won't have the range of a 5dBi antenna at twice the height.

 

One must also keep in mind that antenna gain comes as a compromise.  To make gain, the antenna must have a narrow beam-width... as in the antenna system is designed to pull the energy up off the ground, and down out of the sky, focusing it into the horizon.  If you have a high-gain antenna on a tall tower, it will have great distance range, but will also provide very poor results up close to the tower site.  The signal will simply over-shoot the target radio.

 

Real world case:  I take care of a UHF Ham repeater in Campbell Nebraska on 444.475/449.475.  It is using a DB420, which has 11.3dBi gain, and it is mounted at about 290 feet on a commercial tower.  Other repeaters link into this site from well over 40 miles away.  I live 7 miles away from this site, and can use a 2-Watt handheld from my back yard just fine.  If I travel closer to the machine, I drop in and out, and can no longer hold the machine when I'm 1-3 miles away, due to no ground coverage, and signal overshoot.  I'm inside the shadow ring of the antenna system.

 

Summary: Use a higher elevation, and a not-quite-so-high gain antenna for a project like this ranch.  The lower gain antenna will have much better ground coverage near the tower site, without shadow rings around the site, and the height will make up the distance covered.


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#11 Quarry Creek

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Posted 07 July 2018 - 03:05 PM

I'm following you on this issue about antenna height. Since there is really no hindrance other than proper construction (being on the ranch), I'm actually thinking about building an antenna tower somewhere between 75 ft and 100 ft tall, probably closer to the 100 ft. This height should maximize my coverage area without regard to any terrain issues.  This is plausible for me since I already have the equipment and materials to accomplish this. Will just need to do the engineering to make it right.  I have a little over 4000 ft of 2-3/8 pipe in 30' joints which I can utilize for at least part of the tower. Just depends on the design.

 

This height would also let me stay with the lower gain antenna. Close communications are necessary, but my range requirements are not enormous since this height should give me true line of sight to all areas I'm interested in.



#12 PastorGary

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Posted 07 July 2018 - 06:46 PM

Do you have a 60 to 80 foot windmill tower on your property?   Those work well - especially if the actual windmill blades and water pump rod is deactivated. Just use extreme caution while doing ANY tower work.



#13 Quarry Creek

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Posted 07 July 2018 - 10:49 PM

No, no windmill tower that tall.  The only windmill tower on the ranch was only used to pump out of a creek and is only about 20-25 ft tall.  I think I'm going to get my radios installed and get a base set up in town and just do some testing to see what I need before getting into detailed planning on towers. I'll most likely use a j-pole on a 60 ft tower at my town base and just see how it works with my mobiles first and then start thinking about the repeater and its antenna.  I also don't know how that heavy 2 3/8 drill pipe will work as a pipe mast, so I may experiment a bit setting it up at the ranch where I can work with it safer.



#14 Lee - Texas GMRS Network

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Posted 08 July 2018 - 04:23 PM

Following this... we’d love to get your system linked in to our repeater network. www.texasgmrs.net

txgrmsnet_logo_4_80h_dropshadow_transpar

 


#15 Quarry Creek

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Posted 08 July 2018 - 06:25 PM

Lee, I checked out your website - looks interesting. I am quite a ways from the repeaters you show, but will stay in touch as I progress.  I'm just getting started on the project, so it may be a while.



#16 Quarry Creek

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Posted 24 July 2018 - 11:04 AM

I've ordered my radios/antenna's to start my system, but I had a question about installing the quarter wave on my truck.  Of course its a ranch work truck, single cab with a flatbed and a headache rack on the flat bed.  My question was how much difference it would be to mount the antenna in the middle of the roof of the cab vs mounting it on the headache rack.  The headache rack would be a lot simpler, but I didn't know if it would make much difference overall.

 

Thanks



#17 WRAA720

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Posted 24 July 2018 - 01:58 PM

Roof vs headache rack will make a difference.  For a 1/4 wave antenna to work properly, you need sufficient ground plane; the center of the roof is where you would want to mount this antenna.  If you prefer to mount an antenna on the headache rack, use a 1/2 wave antenna which does not require a ground plane.


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#18 Quarry Creek

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Posted 25 July 2018 - 09:11 AM

Thanks mcallahan, I figured that would be the case, but thought I'd ask. I want to use the 1/4 wave since it will clear brush and trees better.


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#19 WRAA720

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Posted 25 July 2018 - 11:33 AM

A half wave UHF antenna will not be considerably larger.  I've used both on my truck and the 1/4 wave is about 6" vs 12" for the 1/2 wave.  I have a longer VHF whip on the roof that will occasionally catch trees and whatnot on the trail but a UHF antenna rarely presents that problem.


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#20 Quarry Creek

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Posted 15 October 2018 - 03:59 PM

Got my radios, cables, etc to put my base and mobile in operation about a month ago, but haven't been able to finish because its been raining here about every 4 days -- imagine that in West Texas.  I had 4" yesterday and its just been too muddy to get my antenna mast set.  My mast will be about 35 ft. Starting with a simple J-pole antenna just to see how it does, but one thing I noticed is that the LMR400 cable is pretty stiff.  Would a short pigtail from the main cable to the radio that is more flexible be reasonable - if so, what cable would be best.


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