coryb27
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Posts posted by coryb27
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Several mobiles come with removable faces for remote mounting. Most modern mobile radios are between 25 and 50 watts and can hold 100's if not a 1000 channels, it all depends on what you want to spend. This is my truck, the radio is a Motorola XPR 5550 with handheld control head, as you can see antennas for this band can be as small as 6" and still talk 40 miles. This is a part 90 radio not a part 95 radio if that is important to you. I use this on my business system and GMRS. HAMS are also starting to buy this type of radio. This unit will set you back about $1100 but well worth the features and the quality of its construction meets or exceeds several mill specs.
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I keep the 8 repeater channels with the travel tone set on them in a zone and scan well on road trips,its amazing what you will hear and even more so the amount of repeaters that will squelch back that are not listed anyplace. Just for fun I have the entire frs/gmrs list programed into a zone, it goes nuts around parks, campgrounds, sports events etc... Last year I was in the bad lands park in SD, the channels where so busy it sounded like CB channel 6 any day around noon. San Diego looks kind of quiet, may not be a bad idea to put a family repeater on a mountain somewhere.
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Hello Dustin, Welcome to the myGMRS forums! Repeaters are privately owned unless its listed as open and provide the PL / DPL needed to access it. Most GMRS repeaters are stand alone devices and cover a radius somewhere between 5 and 100 miles depending on the type of equipment used to access it and the height of the repeaters antenna and its quality of equipment. I use GMRS as a hobby and backup communications, It is not reliable enough in the event of a life threatening emergency. Since all GMRS repeaters are privately owned you just never know how somebody set up the site. I have seen sites cobbled together with 2 old mobiles, a repeater controller, some RG58 cable and a homemade antenna. I personally only run commercial grade repeaters, 7/8 hardline cable, 16 bay Dipole antennas and try to use towers that offer at min 100' of height. What it comes down to is how much money a site owner is willing to spend and what is the intended use of the repeater. Some people build them for personal use and some people build them for anybody to use. I dont care who uses mine so long as they are legal and dont abuse it. I have access to other systems that require permission from the owner, this can even include the owner checking your license and entering that information into a log book. I hope this helps answer some of your questions, I am sure others will chime in as this site is a library of knowledge.
Corey
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Corey, line of sight (LOS) calculation is nothing but the math of physics. It is a geometrical formula that determines the distance at which the tips of the antennas have a clear, unobstructed path between them, assuming no other man-made or natural obstructions.
The actual LOS could be much less, but never more! The earth is round after all. It would be so much simpler had the earth been flat... <snicker>
Rather than bore folks with the complex math, here is a screen clip of an LOS calculator. I was a bit low because I was relying on my faulty memory. The actual LOS is more like 17 miles. Note that this assumes that the receiving HT or mobile has an average height of 6'.
http://puu.sh/nNq9k.png
Screen clip courtesy of http://www.hamuniverse.com/lineofsightcalculator.html
Now LOS is not an absolute predictor of actual propagation distance, as your observations illustrate. LOS assumes nothing is in the way of the radio signal between the antenna and the horizon at a chosen height above ground. It does not take into consideration any attenuation caused by weather, band conditions, antenna gain, path loss, or other factors such as dB loss in coaxial cable.
Likewise it doesn't consider any favorable circumstances such as signal refraction, reflection, or tropospheric scattering. Nonetheless, the physics and geometry do provide a solid basis for best case performance.
By the way, the actual LOS calculated for your 150' AGL is 20 miles. So your "guesstimate" of 25 miles is reasonable. Keep in mind that the higher the repeater's antenna, the more it is likely to "shoot over obstructions".
One neat site for generating a predictive propagation map is found here: http://www.ve2dbe.com/rmonline.html
As indicated on the Radio Mobile Online website, it uses digital terrain information and a mathematical model to simulate radio transmissions between two fixed sites or between a fixed site and a mobile. The digital terrain information comprises three databases: ground elevation, land cover, and population density, which combined total 200 GB of information.
Since the site is in French, a good English set of instructions may be found here: http://ham.stackexchange.com/questions/1921/how-do-i-make-a-rf-propagation-map-for-a-repeater
Here is a screen clip from there for my repeater. I've been using this map as I drive around the area making tests. I've been very conservative in my estimates, figuring it's better to be surprised than disappointed...
One thing is immediately clear from this. I really should have a more directional antenna with the azimuth aimed southwest. I'm "wasting" a lot of my system towards the northeast and the bloody lake!
http://puu.sh/nNs9N.jpg
Here is a link to mine http://chainolakesgmrs.org/chain/ I have the interactive map hosted on the repeaters web site. I have found this to be vary close to real world experience as i have tested extensively. I totally understand how LOS works but it does not take into account HAAT this is why you will always see diffrent performance in the real world. Not only has this been true for my GMRS repeater but my multi site UHF business system as well. My 150' AGL tower has an HAAT 332', this is why i can work it just fine 40 plus miles away without any issues.
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So the repeater was moved off the mountain? The antenna is at 100' AGL now? That will give about 15 miles LOS average.
My repeater is only a 150 AGL and I get a solid 45 miles in all directions, not sure why 100' would only give 15 miles LOS? I am getting almost 15 miles of HT coverage. From experience, if you have a decent repeater, good cable, quality antenna 100' of the ground and only see 15 miles something is wrong. I would have to estimate 25+ depending on terrain and type of equipment your using to work the repeater.
Just my $.02
Corey
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I have a Motorola pre-selector from an MTR 2000 I would be willing to donate to a good cause.
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anything that fits the radio that covers the 450 to 470 band.
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Keep us posted!
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The only thing i would recommend on that setup is to get an antenna that covers the GMRS band, the Nagoya you listed above is a HAM band antenna.
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There are big repeaters all over your area, sign up for an account and you can reach out to the owners and ask permission to use.
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I would bet if you get rid of the LMR400 and RG58 things will improve significantly. Good luck on the tower hunt, look around and see if you have any independent tower owners in your area. I rent my space from a locally owned tower company and the rates are far better then places like Crown Castle and American Tower. Some local radio stations may even let you put up a community repeater for little or no cost.
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UPDATE! Come on your killing us, how does it work!!!
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Anyone have Midland GXT5000 Radios ?
I would guess most of the users here are using more advanced equipment that offers repeater operation. I am not sure if the Midland GXT5000 Radio is repeater capable or not. I noticed the Midland GXT5000 radio was marketed as a 36 mile 22 channel radio. The 36 miles is not practical in the real world unless you had 2 people in direct line of sight, some smaller repeaters running 40 watts dont offer 36 miles of coverage. From experience you will only see 1 maybe 2 miles and your contacts may be limited as you can not talk to anybody using a repeater and any simplex contacts would need to be on the same PL or DPL privacy tones. Unless you have a lot of simplex users in your community you may not hear anything other then kids playing hide and go seek. If this is a service you are interested in for hobby and daily use I would recommend getting a portable that can do repeaters or set up a small base station. Equipment can be found used on ebay rather cheep, whatever you purchase be sure you can program it. I know a lot of people new to the hobby start with the baofang UHF or DUAL band radios. You can purchase a simple handheld on Amazon with a better antenna and programming cable for under 50 bucks. Theses radios can be programmed with a free software package called CHIRP that can be googled and downloaded for free. Understand theses radios are more of a HAM radio and are not certified for use on GMRS but nobody has ever been cited for it as long as you abide by the rules. This type of radio is how i learned to program and the reason i decided to expand on the hobby, like i said not part 95 certified but none the less good learning equipment, easy to program and easy on the wallet.
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From the looks of where you live I bet a huge GMRS repeater would be vary useful for the surrounding community. Do you have a lot of operators in your area? How are the public communication systems?
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The GMRS band has been open here in Wisconsin. I was able to work some repeaters 150 plus miles away. Talked to several LAG members and a few random people. Anybody else out distance talking today?
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My last tower climb was to install an antenna at 150', cost me $800 but it was for my business system.
I use the same guy for all my climbs be it GMRS or Business he does an awesome job.
So have you tested range on the new repeater yet?
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I like to know who is using it but i dont keep records and believe in the open repeater concept. Once I changed from permission only to community access repeaters I noticed the usage number starting to climb. I built it so others could use it, the equipment does no good to anybody sitting idle for 90% of the time. My hope is to generate some local interest in the hobby by offering solid systems with good coverage areas without the hassle of having to get permission.
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You can not operate a repeater on an FRS channel. A repeater can only be operated on the license GMRS channels. If you want license free, forget the repeater and stick with FRS. If you operate a GMRS repeater, You as operator are required by the FCC to maintain records of user license. If you allow unlicensed users, you could be held liable for facilitating illegal activity. Take your time and read the entire Wiki's so that you understand the Law and the technical issues at hand.
Logan,
I have searched the part 95 rules and can fine no place that says as a repeater owner it is my responsibility to verify the license status of any users. My repeater is listed as open and I do not police it as we do not have issues like the people in NYC. My second issue is your statement "if you allow unlicensed users you could be held liable" but legal advisement from my attorney says if I did not commit a crime I am not liable, since I am licensed it would be the person using my system illegally that is responsible for there own actions. I totally understand that Ignorance of the LAW is not a legal defense but misinterpretation of the law does not make it rule. Just to be sure I searched the FCC legal fillings and could not find a single instance of a repeater owner being held responsible for the actions of another user.
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Okay, after a lot of thought, here is what I've ordered tonight for the new Bridgecom repeater. I sure hope this works out well!
60' of 1/2" LDF4-50A and connectors should have ~1.36 db total loss. A really conservative estimate calculates that 40 watts into the system should put about 28.6 watts into the antenna. With 9db gain, that should be around 228 watts ERP.
My new Rigol spectrum analyzer will be delivered tomorrow and the rest of the stuff I've ordered should be delivered by Wednesday of next week. I plan to do a full sweep VSWR analysis of the new antenna system before the new repeater is even connected!
http://puu.sh/npaXv.png
If you purchased the base model Rigol spectrum analyzer with the sweep generator ($1500 Bucks) it will not do VSWR without an additional license key as well it requires a VSWR bridge. The 2 options Cost another $1325 purchased as accessories.
Corey
Corey
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Are you doing all that through a business license? If so, I would love to chat with you about that. My wife and I use GMRS for now, but out here its decently popular and if I put up the repeater I am building it will end up being a community repeater (closed repeaters have issues finding tower space around here by the looks of it). But we want something secure for ourselves - DMR or encrypted P25... still undecided since both have their pro/con sides. However, I have no idea where to start trying to license repeater capable itinerant frequencies - since I don't want to pay a planner and want to be able to take my repeater and move it.
You will have to pay for FCC Coordination and it is assigned to a location so you would not be able to just move it. I have 3 repeater pairs and it costs about $600 a pair for 10 years. I run my commercial system DMR as the equipment costs less and offers easy multi site connections with an internet connection.
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My suggestion to test between the radio and duplexer would have told you if the tune was good or not.
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If you are using it for talking truck to truck off road you would have no issues getting several miles with a 6" tall 1/4 wave antenna. UHF antennas in the GMRS band are not real tall and the CB firestick is 27MHz and would never work in GMRS. Mobile radios need to be programed with a computer, most of use program our handhelds with computers as well.