WRKC935

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

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

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.