Leaderboard

Welcome to the forum and welcome to the wonderful and exciting world of GMRS! Word of warning: Soon you'll be selling a kidney to buy every new radio you see those clowns on Youtube playing with...

I still use the Bird 43 at home and most of my hobby stuff. for work we use the R&S®NRT-Z Power Sensors. Its slick but not cheap.

One more thing, the emitter of the (open collector) transistor is referenced to ground internally (I assume it is the same as pin 25) so you should not require that connection. Indeed, everything on that port that has an associated ground is to the same reference, at least on the schematic.

OK, I was just looking at the schematic in the service manual (I have the same repeater), and the (open collector) output transistor, 'XP4311' (actually it's an IC with 2 transistors in it) on pin 14 is rated at 50V @ 100mA max. That should be enough to drive a smaller relay coil. However, I'd still go with an opto-isolator as there is virtually zero chance of over currenting the circuit in the repeater. Just my opinion.

Well, yes. The open collector output on Pin 14 is going to require a reference. Basically, and since I don't know the current/voltage rating of the transistor, I'd suggest driving a 5, 10, or 12V relay (with the appropriate current limiting resistor) from Pin 13, through said resistor, through the relay coil, and then to/into pin 14. It may be the open collector output is at the same potential as pin 25. Does that all make sense? I suggest reading through the manual, preferably the service manual, to discover the ratings for the open collector on pin 14. I think the relay or even an opto-isolator is the safe way to go. Indeed, feed the +15V on pin 13 (again through a dropping/current limiting resistor) to the LED anode in the opti-isolator, and then the LED cathode to Pin 14 would let you drive/control almost anything safely, without fear of shorting out or over-current anything in the repeater (Think 4N28 type or similar). ?

In 20+ years of GMRS we never had chatter of nets. It wasn't until the ham lite crown came over to GMRS. Remember GMRS used to be a service for a family and was never used in the ways it is now. Its not a bad thing just different than why I got into GMRS and many did in the early years. Been in public safety for 20+ years and have never heard a net on any public safety system either. It may happen but in the NE you wont hear it unless you scan the ham bands. I guess I look at the linking thing as a change also to GMRS thats not always good. HAM did alot of this and I know of repeaters that are now usesless as all you hear is ragchewing all day from half way across the US. Kinda killed some repeaters for local use.

Nope. Sorry Im not a fan of nets. They should be on Ham radio in my opinion. A national net just ties up repeaters when no one is listening to them.

So I spoke to one of my tower site owner friends and this is specifically what he had to say. I've been in the tower leasing business for nearly 30 years and my opinion is that it would be very difficult for someone to get into the tower leasing business today. I built 12 towers between 1994 and 2001 and all 12 ended up getting cellular tenants. 25 years ago it was possible to get some cooperation from the cellular companies regarding where they needed to improve coverage, today that is impossible unless you are running a 100 million dollar company with 5000 towers. Today, the cellular providers simply WILL NOT give you new site build locations or help you in any way. I know this to be true because I have been trying to get a dialog going with the cell companies for 20 years now. The cellular companies have sweetheart deals with about a dozen very large tower companies and give their new site builds only to them and nobody else. You could argue that a small startup tower company with less overhead could potentially build a new tower and potentially lease it to a cell company at a lower lease rate than what the big tower companies are charging but they simply do not care. So, if you go and build a 500' tower somewhere, or a 250' tower, or any other height without having a commitment from some type of tenant you are taking a huge risk. You might get lucky and have a tenant express interest in your new tower a year later, or 3 years later, or 10 years later. Or, you might end up with no tenants, ever. As was mentioned by others in this discussion, if you build a new tower in any area other than one that is extremely remote and undeveloped you will need to deal with local zoning regulations and permitting. Many jurisdictions now have tower removal requirements which means that, if you build a new tower and nobody uses it for 12 months or 18 months or some similar timeframe your conditional use permit which allowed you to build the tower will be revoked and you will be legally forced to dismantle your tower. If you have a lot of money burning a hole in your pocket my advice is to build new houses or apartment buildings, not towers. That is from a guy with actual experience in playing the game with vertical real estate. And while he is a guy ON the Internet.... he's NOT JUST some guy voicing his opinion without first hand experience. And neither am I. I am also a tower site 'co-owner' and manage the site. I have contacts in the communications field because I work in that field and have clients that are also tenants on various tower sites including the one I manage. I am not gonna tell you to NOT do this. I am gonna tell you that you REALLY need to think about what you are going to do, and be realistic. If the FAA has not granted you a build permit for a 500 foot tower, you are NOT going to get to go that high. I would consider refiling at a lower height and see if they allow it. But I wouldn't file any higher than 250 feet. I don't know where this site is with regard to an airport or a municipality that will have zoning requirements. You have a NUMBER of different regulatory entities that can shut you down with this whole thing and the possibility that even after the tower is up require you to remove it if you don't get tenants on it within a specified amount of time. There are ways around that, and if you get to that point let me know and I will share that info with you. But it costs MORE money in licensing and equipment that you will most likely NOT want to invest to keep the tower standing as it's all donation to the same government entities that are wanting you to REMOVE said tower but are done at a federal level that is out of their reach. And you need to consider this.. vertical real estate leasing is in some ways just like the leasing of buildings and homes. You will NEVER make money with only one site in the long term. You will have times that the site has no income or not enough income to be self sustaining. This is a tax write off to a point, but only to a point. Insurance, property taxes and the like can be written off. But other business expenses like electricity can't most of the time. Point is if you DON'T know what you are getting into, don't assume that if you build it they will come. Because they may not. And a tower site has a limited number of prospective clients to begin with unlike an apartment building where anyone looking for a roof over their head is a prospective tenant.

Need to stick something else in here since someone else brought it up. DO NOT even THINK that amateur radio clubs or individuals are going to want to PAY ANYTHING to be on a tower. They get it in their head that they are somehow providing some critical public service by being hams that they are entitled to free tower space. Then when they get it you need to ride them like a rented mule to get them to clean up their installs to something resembling a commercial level install at your site. NOT requiring them to do so will get coax runs flopping in the wind, hap hazard line runs in the building and all other sort of crap that is NOT acceptable in a commercial communications facility. I am not saying that ALL hams are like this, but there are damn few that will do it right. And when you have a prospective commercial paying client doing a site walk through and the see it. They are typically NOT going to be coming to your site. Specific to what Steve said concerning the high gain antenna's on a short tower. It's not as much of an issue because the low gain antenna's near field will put them in to the pattern by if nothing else 'brute force' of the signal. This is why you can talk on a repeater that has a dummy load attached to it if you are in the building with it or are really close. And there are ways to deal with high gain antenna's on tall towers. It requires power dividers and low gain antenna's lower on the tower to cover the near field that is missing from the main antenna. Problem is it costs additional money that no one is typically willing to spend, at least at first. Then when the customer figures out that it will help their close in coverage, they approach the tower owner and he quotes additional cost due to it requiring additional vertical real estate (occupies tower space) and add's to the tower loading (weight and wind load). So they see an additional 3 to 5 hundred in monthly cost and they back away. Then at the end of the contract, instead of moving their antenna's down on the tower where it would be effective, they decide that the owner is screwing them and they leave the site all together. The tower owner has done NOTHING wrong, but the customer, not being familiar with vertical real estate practices, has decided that they are getting taken advantage of. Cell carrier's don't do this sort of stuff, because they know the game. BUT cell carriers are masters of the game. And THEY play it all the time, everywhere. They know what they are willing to pay and what they SHOULD pay, and there is no discussion on that number outside maybe 10%. And ONLY if they are really wanting on that site. One piece of advice that you might think on is this. There are pieces of equipment called transmit combiners and receive multi-couplers. These devices allow for a number of repeaters to be installed on a specific set of antenna's on a specific band. Meaning VHF, UHF or 800. The receive ones can be expanded to connect a large number of receivers in a band pass but the transmit ones are limited to maybe 8 transmitters per antenna. And this is for UHF. The VHF situation is much more difficult to deal with as the splits from TX to RX on VHF vary wildly and often overlap. But if you are marketing PORTS, you eliminate the need to install specific antenna's per customer, which reduces their cost. You limit your assigned vertical real estate that's occupied, and tower loading which means you have MORE space to rent. That reduced cost to the tenant is significant. A typical antenna install with line and tower crew is 5 to 10 thousand depending on how high, and the market you are in. This is how I am running 2 GMRS repeaters and have the ability to put 2 more on the air by simply programming the repeaters and connecting them up to the equipment. And I have a second combiner that will allow my to install 4 MORE repeaters on ham or commercial frequencies by tuning the combiner and connecting the repeaters to the combiner and receive multi-coupler.

OK, sorry but I am gonna sit here and rip all this apart and make you question why you even CONSIDERED this idea. And at the end of it you will thank me. First off. What sort of business study did you do? Do you have prospective clients? Have you done an ASR search or even rented an 80 foot man lift jumped in it and went up to see how many towers are in the 2 mile radius of the proposed tower site? How many roof mounted antenna's are there (prospective customers)? If there are other towers in the area what sort of loading do they have? Or are they occupied at all? 300 vs 500 vs 190 or less Do you HAVE a signed contract for a commercial broadcaster? If not what the hell do you want with a 500 foot tower? NO ONE is going to want to go on the top of that stick that's NOT a commercial broadcaster. First issue is you can't hardly get a commercial two-way license with that sort of AGL antenna height. a Typical FB2 (fixed base / repeater) license is going to give the license holder a 20 or 30 km radius from the point of the transmitter site. Commercial radio is NOT like ham or GMRS where you talk as far as you are able legally. You can only operate inside your radius and you CAN get fined if you exceed that. The best way to limit that is to install a system that will self limit it's coverage by keeping the antenna below a certain height. Now this height will vary depending on topography, but unless you are in a 400 foot deep valley and have little interest in local coverage, parking antennas at 500 foot is pointless. 300 feet is getting back into a reasonable height and 180 is even better for MOST of the current radio technology that is going the small cell route for coverage. Low antenna's, low power and multiple sites. So 500 foot would be maybe 250 foot of usable height and another 250 of unoccupied steel that you are going to be paying for. Tower classification for lighting and height Tower's have lighting requirements based on height. The shorter the tower the less lighting it needs and the less upset people get (the FAA) when the lights are out. Towers to 350 feet are the first class. It then goes to 499. After 499 it frankly gets expensive and watched closely. And something as simple as a relamp can cost thousands of dollars to get a tower crew to do. Then you have to pay for a monitoring service at that classification as well. Not to mention that a single D1 strobe will cost 100 bucks a month in electric. A multihead high intensity system for a 500 foot tower is WAY more. You did say you have a SIGNED contract for a tenant right?? Dropping to 190 If you drop the height to 180 which would legally allow for an antenna that has a tip 18 feet above the mount point and a ground rod to extend above it, you have NO lighting requirements in most instances unless you are within a certain distance of an airport. And before you get it in your head that you need the height for talking distance. I have a GMRS repeater that on a good day will talk 60 miles from the transmitter site and the antenna is at 110 feet. This is in OHIO so it's not sitting on some 10000 foot elevation mountain top. The AMSL is 1350 at the ground. The tower is 240 foot total height to the tip of the lightning rod. I have dealt with repeaters with sky high antenna's. There is a 1092 foot tall tower in Columbus that has two UHF repeaters at 750 feet. The repeaters are up there to minimize line loss. They talk great.... in Dayton and Springfield. But NOT at all in Columbus because the near field coverage from the antenna's never reaches the ground. Gain is too high on the antenna's. So they will talk to the helicopter, but NOT a road vehicle. Something to consider with your 500 stick. The other thing with broadcast is power output, and wasted space on the tower. Any broadcast, be it radio or TV is gonna be high power, Meaning the commercial radio stuff will need to be several hundred feet BELOW the top of the stick where the broadcast antenna is. That offset is wasted space. Nothing can go there. So you either try to charge the tenant for the wasted vertical real estate or you eat the loss. Another things to consider. Better plan If you have property that will support a tower in a marketable area you need to approach the major players in the vertical real estate business and see if they are interested in installing a tower at YOUR location with them footing the bill for the construction. If there is market, they will be all over it... and that's what they do. If there is no market they will have no interest. That makes the math a lot simpler when trying to figure out if you want to lay out 250K on a tower build. And DO NOT forget a shelter, generator and the other added expenses of a tower in the total cost. Your quotes probably do NOT include that stuff.

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.