DONE
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What do you consider significant loss and what do you feel is a truly significant loss ? 3dB,, maybe 6dB? What if I told you I have a UHF repeater system that the stations are all turned down to 20 watts (they will NOT go lower) had an antenna system loss (cable the combiner loss) of 12dB and talks 40 miles in all directions.
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Lead walls are really not that good. IF you really what a space that has ZERO RF in it you need a Faraday Cage. You can look this up but i will give a brief explanation. You need to DOUBLE line the space with wire mesh. They make copper mesh for doing this, but aluminum window screen does a pretty good job. This needs to FULLY enclose the space. Ceiling, walls floor. If you are looking to build such a room, start with creating a floor frame for the room to set on or have access to install the screen on the outside of the studs all the way around the room. This would be done on the outside of the studs of the room. THe outside of the room at minimum gets grounded on all four corners, and the four ground rods get bonded together. Then on the inside of the room put up another layer of screen and then you can drywall it if you desire to do so. Offset the screws or nails from the inside to the outside to that there is NO connection between the two. The door for the room need to have BOTH layers of screen and they need to connect independently to the two layers as well. The inner layer can use a wire and the outer layer can use brass or copper weather stripping or finger stock if you really want to go the distance. ELECTRICAL For electrical there are a couple things that need done here to keep the RF OUT of the enclosure. First is the power feeds need to be transformer isolated. The second is the isolated side needs capacitors to ground That are of a value that they will shunt RF to ground but allow 110 volts at 60 Hz go. There is a manual online that the military created on grounding and RF shielding. That manual has the values of the capacitors needed. The effectiveness of a properly build Faraday Cage is simple. There is a 130 plus dB isolation from the inside to the outside. Or in layman's terms. If you are 50 feet from a radio station and you take a radio tuned to that station frequency, when you close the door you will no longer hear that station.
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Yes, and that owner/operator is the 'manager' of that transmitter. He has control of the repeater the same as the non-owner system user has control of his radio via the PTT button. If I have a repeater located at my home or a tower that I have access to where MY equipment is installed, I need to have positive control of that equipment. That is for when the equipment has a failure and gets stuck in transmit, is off frequency and causing interference on an adjacent channel or someone that is operating without regard to the regulations for GMRS then I as the owner need to shut down that repeater. The reason that you are allowed to NOT have an ID be transmitted on a private repeater that is ONLY used under the owners license is THEY are required to ID. When they ID, since it's the repeaters call sign that covers the ID for the subscriber radio (mobile, portable or base station) AND the repeater. If ANYONE else is on that repeater, that repeater has to ID. And the reason is simple. Unlike commercial repeater licenses that indicate WHERE a repeater is located, when a GMRS repeater is at a remote location, there is no FCC record of that transmitter. And if it's not IDing, the FCC has no idea who's repeater it is. That's why the repeater has to ID if others are using it. I ain't the FCC and I ain't your daddy. Do what you want. But don't blame ME when you get dinged.
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Read this carefully. If you have a repeater and everyone is properly IDing on it, you are fine. If they are NOT properly IDing, then they are violating the regulation but so are you by "allowing" them to access the repeater. If the repeater does ID then you are covered on that front. Now what that means is if you don't have the ability to immediately down the repeater (sort of hard with JUST a back to back cable) then you are allowing them to operate on your repeater illegally. This is a common thing with HAM and why every repeater controller has a disable function. It's YOUR responsibility to control your transmitter, including the transmitter on your repeater. And remember that while part 95 specifically pertains to GMRS, there are other regulations outside of part 95 that apply to all radio services. If you don't want to program your call sign into your repeater, or you have two mobiles with a back to back cable between them and are calling that a repeater and are too cheap to buy a CW ID board or build one up with a Raspberry Pi or an Arduino, that's on you. Because ONE of those regulations that applies to overall radio communications and all services is if you get your license pulled for being dumb..... it's not JUST your GMRS license they take away. You can loose the ability to have ANY FCC issued license. SO no part 90 commercial, ham radio, or broadcast license either. I said what I said to cover your butt and mine. Because in truth, it's MY call sign on the profile... and if you get dinged and are all crying to a lawyer about it, saying you heard it on the interwebs from me. It may or may NOT be a winnable case if you sue me,,, but the FCC will get their money first and lawyers to defend dumb lawsuits are not cheap.
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Updated FCC Rules (2021) Pending - GMRS Location Data and FM on CB
DONE replied to mbrun's topic in FCC Rules Discussion
Pertaining to the digital data transmission on GMRS for location info.... whatever. For the FM on 11 meters, gee, why wasn't that the way it worked to begin with. If you look at CB and what it's turned into, if it was FM from the start we wouldn't have near the interference issues with it. FM is constant carrier level. So a 'peaked and tuned' FM radio would just sound bad and not talk any further. And even running huge amplifiers on an FM radio will still not generate near the interference and splatter that AM does when it's over modulated. Driving an amplifier into square way output (clipping) causes distortion which is the big issue for causing interference. If the modulation is FM, this isn't really a thing. Radio transmits 4 watts, regardless of the modulation level. But then again, the FCC has turned a blind eye to CB anyway. "Export" radios are prevalent everywhere and you can hear guys talking on them from somewhere down around 25Mhz all the way up to the bottom of the 10 meter ham band. So trying to regain control of that frequency band is about pointless. -
Fun topic - SHTF communications plans and equipment?
DONE replied to Lscott's topic in Miscellaneous Topics
Yeah, thanks for 'the flowers' But I think we are referring to two different types of threats. The two legged threat is a consistent issue in all areas. The threats I was actually referring to were the natural disaster type stuff. I am in OHIO so I really don't expect a hurricane or an earthquake as a primary threat source here. We do gets some minor flooding, tornadoes. Other stuff not so much. I am fallout close to a major metropolitan area (Columbus) that may catch a nuke of things really got going on with a nuclear war situation, but we are not a dirty bomb target. We are however a major hub for freight and overseas goods distribution as you can reach 80% of the population of the USA from Columbus, Oh inside 10 hours. That could draw attention from those meaning to break the supply chain. Other places have other threats. If you go out to tornado alley, your primary threat is obviously tornado's. But my point is that you need to prep for what YOUR area may throw at you. -
Fun topic - SHTF communications plans and equipment?
DONE replied to Lscott's topic in Miscellaneous Topics
I think bringing up EMP is only partly useful here. Yes, it's ONE of a dozen or more possibilities that COULD happen. But keeping a cache or radios in a metal box is all that is needed to prevent them from being damaged. Should you have a spare stash of radios for that sort of thing, sure. Being prepared is a multilevel thing that needs to happen over time. And as said before,,, this is something that requires planning and considering what sort of situations are MOST likely and prepare for those first and then work down the list. Someone brought up water. That comes before radios, or anything else, even shelter. Once you decide to prepare, before you go BUY anything, you need to look at Maslow's Hierarchy of Needs. This spells out what we need to survive and thrive. The basics have to be covered first. Then you build from there. And another consideration that seems to have been missed here. You need to first figure out what the threats are for where YOU are and where you will be. You then need to consider your storage of your stash and how those threats can effect the stash and how it's stored. If you have ammo buried in the back yard and you are in a flood plain for a dam, if that dam bursts, your buried ammo is useless because you will loose access to it. Same thing if you are in an area that can have land slides. ANd these are just two examples. Point is that you need to think it through pretty well and cover all your bases. -
Petitioning to get a few VHF frequencies added to GMRS
DONE replied to Hans's topic in FCC Rules Discussion
So while I understand the want / need of a vehicular repeater for extending range of a portable radio, if you do this on MURS you open up the possibility of a non-licensed operator gaining access to GMRS repeaters without that person even knowing they are doing so. Some MURS operator with the right frequency and PL code would access your vehicle repeater just like you would be. This is why you also can't do an in-band repeater on a FRS frequency. Joe Blo with his/her blister pack radios is suddenly on the local GMRS repeater. Yeah, that's not gonna go over too well. And honestly. If you need access to a GMRS repeater that often that you NEED a vehicular repeater to gain that access, you need to be on a commercial frequency and not GMRS. Of course at that point, you can get a VHF and UHF or whatever and have a vehicular repeater. But the issue I see with all this is having two different radio services linked. -
Fun topic - SHTF communications plans and equipment?
DONE replied to Lscott's topic in Miscellaneous Topics
Yeah, the idea that there would be roving gangs of people out with this sort of technology is just not realistic. I was trying to spoon feed this. But there are simple attainable methods for avoiding the laymans approach to DFing a signal. The easiest is using a directional antenna and moving it after each transmission 10 degrees or so but maintaining the general direction of the signal. The reason this works is the received signal by the person trying to track you with an S-meter or even a spectrum analyzer is going to see a variance in the signal lavel. Of course tracking a signal down using the signal strength method requires that signal to NOT vary in level so that as you approach it, the signal rises in level. If you drop 10 db then increase 5 db then drop 6 db trying to home in on that is a bit difficult. And in truth the person that is gonna know how to combat that is NOT gonna be the one leading an armed group of thugs bent on taking your stuff. Now since we are gonna really discuss this. Lets do just that. I said that there was planning that was involved that needs to be done PRIOR to a situation. And where I was saying simple things like who and what with communications. There is a lot more to that. The first thing with a real TEOTWAWKI situation that is going to take years to correct if it happens at all is you are NOT gonna be able to survive that on your own, or with just your family. As the fuel finally completely runs out and you need to start farming the way it was done in the early 1800's without tractors and planters you will need groups and communities to pull together and pool resources. You are going to need to figure out who those folks are and then figure out communications with them. There are circles of communications. We have this in day to day life. There are things that you will tell your wife you would never tell your buddies, but might discuss with CLOSE friends, these are the circles of communication. And planning on HOW you are going to communicate with those people is key to survival. Then you are going to have security groups that will be task with community security, that no one but that group will have communications with. Again, we have this now. SWAT teams have secure radios that the average beat cop can't access. And there is a reason for that. I talked about pooling resources. One of those resources is the guy or guys that setup the communications. There are people (mostly the phone guys) that will be able to get into the phone central office, acquire a number of solar panels and bring some number of phones back on line at least within that CO. Others that are network engineers and the like will be putting some level of computers back up and leverage thing like STARLINK which will still most likely operate since the birds are self powered. While there will NOT be a Facebook or Instagram to entertain you, the idea of someone spinning up a solar powered Raspberry-Pi with a mail server on it will be very possible. And this sort of this will not be isolated. But these sorts of things are going to be important. But planning is key to ALL this. And figuring out number one who do you trust at that level and two what skills do they have to be leveraged will be key to getting things back to normal. -
Fun topic - SHTF communications plans and equipment?
DONE replied to Lscott's topic in Miscellaneous Topics
I don't disagree with either of you but every bit of what both of you said goes to the prior preparation for a situation. You need to know who you are gonna be communicating with and how that communication is going to happen. More over what is gonna be communicated. You are not gonna like the outcome if you are discussing on an open GMRS or FRS frequency about what materials, food stuffs and equipment you have and then talk about location. Sent from my SM-N960U using Tapatalk -
Fun topic - SHTF communications plans and equipment?
DONE replied to Lscott's topic in Miscellaneous Topics
Hmm, I spoke elsewhere on this topic. Here's a dumbed down version and a few extra thoughts. You need to consider ahead of time what and to who you are wanting to communicate. You also need to carefully consider what sort of disasters that you are going to prepare for based on what realistic situations you may encounter in your geographical location and, or the geographical location of your bug-out location. And understand that EVERYTHING I am saying is based on a situation where the FCC and current regulations that we all follow on a normal basis will be out the window if the situation degrades to a point you are bugging-out and seeking shelter elsewhere or have hunkered down and have 24/7 armed security as part of you op sec plan. First topic is encryption. Again, we are discussing a situation that no one cares any more. First level is the basic DMR encryption, there are two levels, basic and advanced. Your programming can provide specific channels and zones within your radio that have secure channels. This is a good start. No one that you haven't provided a key to will be able to listen and NO scanner will decode this type of communications. Going hog wild and getting high end radios with AES256 is not needed as the government is NOT gonna be bothering with you at this point. Second is common bands and frequencies. Programming up stuff like GMRS frequencies, MURS frequencies and the like and then encrypting them will draw attention. It's unwise to think that just because someone is a radio nerd that they wouldn't come take your crap is dumb. So a second layer of security is odd bands and frequencies. If no one is using 900 Mhz around you,,, that is where you need to be for that additional layer, and in truth using 900 in an area that has no traffic in that band even without encryption is still better than running around with basic encryption on UHF in the GMRS allocations. Lots of people will be listening there. The top layer for op sec by a large margin is FHSS or Frequency hopping spread spectrum. These radios will transmit bursts from 40 to 200 Mhz and are unmonitorable by any normal equipment or scanners. So these radio's will not only stop basically ANYONE from listening but will also not provide a method for others to track you by your signal. Bear in mind that any situation that will last for over a month and is significant enough that FEMA is gone home people will be on the air telling tails of whoa and suffering to get you to either give away your position or draw you into a trap so you can be robbed. You will need to learn to trust basically NO ONE. This may be simply not trusting their decision making abilities when dealing with the new normal and others that mean to do you harm, or even the possibility THE ones closest to you may purposefully betray you for reasons unknown until that situation arises. So, in short, if you are worried about your radios in a SHTF situation, have you gotten all the other ducks in a row and are prepared in the countless other ways that you need to be? Because the radio may play a roll in saving you or someone you care about. But it's gonna be worthless if you haven't prepared for yourself to survive all the rest of whatever the situation is. -
Could be a number of things. The car generating RF noise is a possibility. It might have been as simple as someone else with a GMRS/ FRS radio playing around. The fact that it was heard on multiple radios indicates that's it's certainly an external source to the first radio that heard it. With the amount of electronics in a can in this day and age, I would vote that it was some part of the vehicle that you were in
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I too use Radio Mobile a good bit for things from 2 Meter ham radio to 5Ghz microwave links and find it to be very close to actual tested results of a system built on the numbers provided by Radio Mobile. The comments I made before pertaining to "the math" involved in calculating path loss and attenuation is what this software uses to create the coverage plots and the point to point link signal levels. But you need to feed it correct information for it to give accurate results. Here is the other part of what this can do but folks seem to forget it's importance. It will also show the mobile to base signal expected signal levels. Now with simplex operations, this is not overly important as two mobiles that are 20 watts or 2 portables that are 2 watts are going to be reciprocal in performance, in other words, if A can talk to B then B will certainly talk to A. With a repeater this is NOT the case. Now you are talking about antenna height differences and power differences on the level of 10 dB. For reference a 10dB increase is basically you add a zero. If you have 2 watts and increase it 10dB you have 20 watts. So then the whole I NEED 50 WATTS for my repeater starts to show it's uselessness. Because no matter how far your repeater may talk out, if you can't talk back to it, it don't matter cuz it will not work for you beyond that point. And to drive that point home I was range testing yesterday while on a service call. I went from Johnstown Ohio to Indian Lake Ohio. I finally fell out of the system (my repeaters) at Bellefontaine,Oh. At that point I was hearing the repeater on and off and was not consistently able to bring the repeater up. Here's MY setup. I am running an MTR2000 (both repeaters) one is set 50 watts and the other is a 40 watt repeater. These are both connected to a 4 channel transmit combiner that has 6dB of loss through the unit. This runs to a stationmaster antenna with 8 dB of gain through 200 feet of 7/8 cable and a 1/2 inch jumper to the surge suppressor. That works out to about 3 dB of loss. So a total of 9 dB of loss and an 8 dB gain antenna. The air distance for this is 60 or so miles. and it worked on BOTH repeaters equally, so the 10 watts of difference had no noticeable effect on the range I was able to attain. And I was talking back from a van with a 35 watt mobile and a unity gain (the little wire motorola style) antenna. Not some high gain antenna. This speaks volumes to the importance of antenna height.
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OK, while not trying to make this overly complicated, I will only mention these concepts and not the math behind them. First off is that 3 dB of loss is meaningless when you start looking at the overall effect it has on the range of a radio system. Consider that a CB or ham radio with an S meter registered S-1 to S-9. The change of one S unit required the signal to change 6db. So if you were running 10 watts and were being heard with an S-8 you would need to increase your power to 40 watts to bring the meter up to S-9. And what did that really do to the overall signal quality? Not much. Here's the thing NO ONE ever brings up and involves the most math. Path loss. Path loss is the signal level loss though free space between the transmitting and receiving antenna's. And it's going to be over 100 dB. And this it where people fall flat with the idea of cable loss and antenna height. Path loss can indeed be calculated and the attenuation levels changes depending on the medium. The other this that no one takes into account is horizon. UHF signals do NOT bend in the atmosphere. They radiate in a straight line away from the antenna and once they reach the horizon they keep going straight. No amount of power increase will change this but a height increase in the antenna does. The other thing that the height increase changes is the medium that the signal is required to pass through. Meaning if your antenna is 5 feet off the ground, the signal coming from it has to radiate through trees, houses, buildings, and the minute it hits a hill it's done going that way. All of these objects attenuate the signal of block it completely. A typical building is going to be over 30dB of attenuation. So if the building is 90 feet tall, and to get over it requires a 3 dB loss of signal to radiate past it, then you loose the 3 dB in the cable to make up for the 30 dB loss trying to pass the signal through the building. Yes, you can over so it and place an antenna too high in the air. But unless you have a 1000 foot tower this is a topic NOT worth discussing.
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30KW plus. The actual setup for many of these is a special custom wound plate transformer that takes a very high amp alternator and connects the 3 phase output that is typically held to 50 or so volts and steps it up to a proper plate voltage for the tubes they are running.
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You just got your GMRS license, now you want your own repeater?
DONE replied to coryb27's topic in General Discussion
Alright. Since I am the guy with the tens of thousands of dollars setup and the commercial install I believe I need to interject here. Never did I say that a small repeater system is useless. And there are COMMERCIAL repeaters available that ARE indeed two mobiles in a box with a controller between them. And those work find if that is all you need. My point was if you are going to put up a big commercial grade install that you need to NOT pull the crap of wanting fee's paid for access, as this level of install has a huge footprint that will interfere with other repeaters on the same frequency in that footprint. And the frequency resource is limited for repeaters. I am all for guys that want to put up a repeater on their roof or short TV tower and be able to talk 8 or 10 miles. This sort of thing SHOULD be encouraged. But you still need to be aware of others on the frequency and try to find a quiet pair to set your repeater up on. The other thing that needs to be said here is IF you are going to stick an antenna WAY up in the air and cover a 60 to 80 mile radius, you DO need to have good commercial equipment and not two portables with a back to back cable between them and a cheap duplexer. And here's the reason. If you are the only one that will be using it, and the usage is light, it don't matter. But with a big coverage footprint there is a good chance that it will see a lot of use and portable radios are NOT designed to be run at that duty cycle. The commercial repeaters I use for GMRS are 100% CCS (continuous commercial service) rated. This means they are designed to be transmitting up to 100% of the time, 27/7/365 and live. If you were to try that with the two back to back mobiles the transmitter would not survive the abuse, even with a fan and additional cooling. Now, my repeaters are only logging 30 to 45 minutes of use a day currently... but that number keeps increasing. And that's fine. I built it to run all the time, and offer it for free to all licensed users in the coverage area to use at their leisure. But I would hate to see someone put in inferior gear at some remote site and it die when it was needed. That situation is actually worse in my mind than it not being there at all. Because if it's needed and expected to be operational. And that operational repeater is part of someones emergency plan, then it needs to work as such. -
Whats with repeater users needing permission on GMRS?
DONE replied to w4thm's topic in General Discussion
IanM brings up a lot of good points and I am planning on putting together a sort of HOW-TO on frequency coordination. I will say that it would take cooperation form the GMRS community. But, if that cooperation could be obtained, it would work out well for all involved. In fact, it's something that MYGMRS.com web site could possibly host the data for so that it would all be public and guys could look at it and hopefully administrate it. There is a coverage mapping software that runs here now, but far as I know it ONLY shows the footprint of the specific repeater you are currently viewing. I hear the comments about being limited to 50 watts. Well, here's the thing with that. You are trying to communicate with portables that are 4 watts and mobiles that are 10 to 40 watts typically and have antenna heights below 10 feet. I have two repeaters on the air currently. One is 40 watt and the other is 50 watts. They both have a coverage footprint that extends over 30 miles in some directions. And because of the antenna system I am running. One transmit and one receive for up to 4 repeaters. The loss in the transmit combiner with 50 watts in means I am getting about 12 watts coming out of the building headed to the tower and antenna. And I cover over 30 miles. -
Couple things here to the guys that JUST got their license and are trying to make a contact. First.. POST YOUR CALL SIGN. Second .. POST YOUR GENERAL LOCATION If we don't know who you are and where you are then we can't really assist you with where an unlisted repeater might be. You could be our neighbor and we don't have any idea. My call is my user name here. But that is easily converted to Keith Foor and my address since the FCC posts that info. Once we know where you are we can tell you about repeaters that you can access if we are in the same area and any specific programming that they might require.
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Yes, connect a ground wire to it and then wrap it with butyl and vinyl tape to weather proof it. Make sure to properly connect the other end of ground wire to a proper ground.
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You are right, depending on the cable run length and how often you want to change out the cable. 400 is kinda lossy if it's over 100 feet.
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I put 1/2 heliax connectors on for years with nothing but a pocket knife and a couple cresent wrenches to tighten the connector body down. If you are using Andrew / Comscope connectors they come with a guide for doing this. Follow the directions and you will be fine.
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ANSWER.... What are the proper steps to putting a GMRS repeater on the air?
DONE replied to DONE's question in Technical Discussion
I want to thank JeepCrawler98 for pointing out the ID requirements for a repeater. If you are the ONLY licensed user and the repeater is closed to all others, and everyone uses YOUR call sign legally under the rules then it doesn't have to ID. If anyone else uses it, it needs to ID. And in truth, it's just easier to have it ID. Now for those that don't want it to sit there banging away every 10 minutes with an ID, use a commercial repeater and allow the repeater to ID through the programming. This will be at a set interval as long as the repeater is active. Meaning that if no one is talking on it, it's doesn't ID. That is within the regulations. I have heard HAM repeaters that bang away every 9 minutes. In fact I have one local to me that has two ID mechanisms in it. Both are voice. They are set at 9 minutes and 8 minutes. The 9 minute one is EVERY 9 minutes without fail. The other one is active only. But you can all but have a conversation with the dumb thing because it talks so much. DON"T BE THE GUY WITH THE HAMMIE NONSENSE TALKING REPEATER on GMRS. That is unless you really don't want other people to use the repeater. ANTENNA LOCATION So you have gathered a bunch of parts together and now you want to put your repeater on the air. Question is where are you going to put it. We discussed that antenna height is KEY to how far will it talk and hear. If you put it on your garage roof, it's gonna talk a few miles but nothing crazy. If you want to have the big dog, you have to have have a big tower. Now there is software that is online called RADIOMOBILE that will plot coverage maps out for you based on the info you put in and maps that it pulls from the Internet that I have found to be reasonably accurate. You key in all the info and it pops out a map. And because it's computer based, and you are controlling it you can create maps with different antenna heights and locations that you can reference. I will tell you this now and save you the headache. For the most part, if a tower is owned by one of the major tower companies, they are going to want at a minimum 1000 bucks a month for access to hang an antenna. Will require you to hire an approved tower company to install the antenna. You will probably be required to get your own electrical service and carry insurance as well. Now there are exceptions to this as well. I currently have the ability to put up all 8 repeater pairs via the antenna system I have. I run a receive multi-coupler and a transmit combiner. I am currently only hosting two of the 8 pairs on repeaters. I can't say that I am the only person in the entire USA that would do this, but IF you need hosting in central Ohio, have a name brand repeater that is RACK MOUNT, and are willing to cover the bit of additional electric, I will host it on my tower. That being said. AGAIN, if YOU have this sort of setup, you should be willing to do the same in my opinion. -
ANSWER.... What are the proper steps to putting a GMRS repeater on the air?
DONE replied to DONE's question in Technical Discussion
The next bit is the duplexer. And there are a number of options here as well. The point of install is going to set the requirement for what gets used. The little flat pack UHF duplexers are very usable on GMRS in certain instances. Those are going to be the smaller installations on a relatively short town (under 100 feet) in an rural setting or maybe a suburban setting where there are not a lot of other repeaters near you. These duplexers work on a frequency reject configuration where the input side rejects the output and vice versa. There isn't a pass component to this style duplexer, which means that the specific frequency and a few kilohertz above and below it are blocked but EVERYTHING else is passed through. This becomes a problem for installs where the antenna is receiving a number of other things, both UHF and elsewhere on the band and allowing that RF to get into the receiver of the repeater. The reason this is a problem is the first amplifier in the radio receiver string can only handle so much signal before it gets swamped. For a quiet area, it's not a big concern. If you are at a tower site with many other transmitters then you will need a pass/ reject type of duplexer where the frequencies of interest (TX and RX) are the only frequencies that are passed through the duplexer and everything else gets rejected. ANTENNAS and HEIGHT Here's where the distance that the repeater is going to cover really gets set. There are some folks that will tell you power level is everything. I am here to say that's false. I have a repeater system that I maintain for my employer that can be heard 60 miles from the transmitter site. And it's turned down to 20 watts coming out of the repeaters. The antenna height is over 500 feet however. And it still talks farther than it can effectively hear. Add to the 20 watts the fact it goes through an 8 port combiner and looses another 6 dB of signal level and is feeding 650 feet of cable (more loss) and it's only getting about 6 watts to the antenna connector. Point is that if you really want to cover a LOT of area, height is key to doing so. But know that you are NOT gonna be able to run LMR 400 or 600 up a tower like that and have good results. Cable loss is figured in dB per 100 feet or 100 meter lengths. If you look up what cable you are using, it will have the numbers for the frequency range that you are operating on. This is important on long runs. Anything longer than 100 feet for UHF really should have 7/8 cable at a minimum in use. Getting to the antenna. I have spoke to people that were looking at using some mail order antenna thing that you went to a hardware store and bought PVC pipe to build the antenna. This might be ok for your home base station or repeater. But I have built these types of antenna's and they doing hold up for very long. Find an Andrew / CommScope or other commercial antenna and use that for a repeater. You will have much better luck and will be happier when you are not needing to replace the antenna every 6 months because the wind broke it. -
It's possible. But it's most likely stupid expensive and totally out of reach. Unless you are on a mountain top and are moving to another mountain top on the other side of a valley. GMRS radio operates line of site. So you run into the horizon at 10 miles typically. This varies some, but is a good point of reference. To overcome the curvature of the earth we use towers. So to add 1 mile of range, you need 25 foot of tower past the horizon. So you either stand up a REALLY big tower at one end, or you split the difference and fine a tower in between because talking 50 miles might only require a 200 or 300 foot tower. Remember you ask if it can be done.. It can. It's also gonna cost a LOT of money. Your other option is HF ham radio, and NVIS antenna's at both ends. Of course EVERYONE using the radio would need their own ham license. Personally I would just get a cell booster, stick the donor antenna 30 or 40 feet in the air and point it at the nearest cell tower and put the other antenna in the house. Then the cell phone works and you can communicate with everyone and not just family.
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Go pop some popcorn and kick back.... This WILL be a long read. So you have you license. Now you want to put up a repeater. Great,,,, maybe,, usually. But have you thought it through or do you just really want to hear your call sign coming across the airways if CW? This is going to explain how to do it right to NOT cause interference with other repeater owners and be mindful of the limited resource (8 repeater pairs) we have been designated by the FCC. This will cover planning, equipment, antenna's and everything in between. Please ask questions about the topics as they are posted, and if you see something missing you would like covered, message me and I will do my level best to cover that topic. I have been a commercial two-way radio tech for 13 years a ham for almost 30 and have been working on electronics and radios for 40 years. First thing is to listen. Listen to the repeater pair OUTPUTS. These are the 462 frequencies in the 462/467 pairs. They are what the repeaters will be transmitting on. The reason you want to listen is you want the quietest one for your area. Now that doesn't necessarily mean the one with the least traffic. So if you have several repeaters around you that are not all that busy, but the signal from them is always very strong and clear and maybe a busier frequency talks alot, but is far off in the distance 4 towns over, any your plans are for a small footprint, with a 30 or 40 foot tower, that may well be the better frequency to choose. You need to consider a couple things here. Number one is the total number of pairs available. We only have 8 for EVERYWHERE. Why is that important? Because the guys with the monsters, like me how just talked to a guy 40 miles away from his repeater, can cover huge area's with their repeaters. And some of them see the value in what they have and allow others to use it openly. That's my stance on it. I say the same thing to everyone that asks. Make sure to ID your station and have fun. But if you are sitting on an otherwise open frequency, he may not use it for a wide area coverage machine. I am thinking on writing a thread on frequency management at a state level for GMRS, but that comes later. So back to the footprint you are looking to achieve, and you need to be reasonable here. Don't decide to build a monster, tie up a pair and make the repeater closed to all but you and your wife and kids. That's not proper use of the airways. And in my opinion is a bit of a dick move. SO lets say we are going to use that pair that you can hear a repeater on but it's very weak signal and can't always be heard. You NEED to locate the owner of that repeater and verify where he is located. If he's a weak station but he's right up the road, then don't use that frequency. If he's 2 counties away, you are golden. You need to find out what PL or DPL he is using on his repeater and NOT use anything close to that. If he's running between 67 and 103 you want to be at a minimum at 141.3. This will minimize the potential of interference. You also need to verify that you are either very noisy into his repeater or you can't hit it at all from most of the footprint area you are wanting to cover. Now a quick side note. Repeater talkout (how far it talks) is controlled by two things.. first is antenna height. Height is FAR more important than power level. But power level does play a role. And you ONLY want to run enough power to provide signal levels in your desired coverage area to capture the receiver of a mobile or portable radio. Meaning, if you are wanting to cover X number of square miles and that can be done with an antenna at 40 feet of height and 10 watts, Don't set the repeater up to 50 watts. It's not necessary and again, it's not good frequency management. So you now have a pair picked out. What about a repeater? A repeater is required to ID unless YOU and those under YOUR license are the only ones using the repeater. The minute that other license holders are allowed to use the repeater, it needs to ID itself. Now this can be done with a Raspberry Pi, an Arduino or some specific module for CW ID. You have options. You can use two mobile radios as a repeater with a cable between them and an ID board. You are not required to have voice announcements, roger beeps or any of that. So it can be a simple set of radios. (Motorola CDM series work great and the 16 pin interface makes connecting them very easy). Or you can buy a repeater that is a purpose built device. There are a number of options. More to come.... stay tuned.