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The more I learn about the FCC's General Mobile Radio Service (GMRS), the more I am fascinated by RF in general. It touches everyone's lives every second of every day, yet few people pay much attention. How cool is it that after 42 years and 14 billion miles away, the 22-Watt radio on Voyager 1 is still sending data back to earth every day (how important is that antenna?). So why aren't more people interested in GMRS or RF in general? There's no test to get a license like amateur (ham) radio. It's $70 for a 10-year license, and is really easy to get started. So here are some theories. People don't know: GMRS exists Why GMRS exists Why they'd want to use GMRS How to envision themselves participating in GMRS What it takes to get started with GMRS What it takes to continue and improve with GMRS Technical information they should know about GMRS Etiquette when transmitting (TX) on GMRS What a GMRS "Net" is and why Most people within the GMRS community are helpful once you're in, but the community is very inviting in a go-figure-it-out-yourself way, and no one has assembled everything you need to know about GMRS all in one place. We GMRS people are putting the onus on outsiders to sift through thousands of painfully esoteric webpages with a winnowing fork, separating useful info from useless, poorly written, or incomplete info. When I first heard about GMRS on a 4x4 trip, I arrived home and Googled around and settled on a Midland MXT-275 because it seemed perfect for mounting on my truck dashboard. At the time, I had no idea that Midland doesn't manufacture a GMRS radio capable of operating on split-tone repeaters (Dear Midland, I know you're reading this: why do you squander so much potential?). Edit 6/28/2021: Midland heard our cry! They just updated the MXT-275 to include split-tone programming on repeater channels. So for example, now this radio is able to reach a repeater that receives (RX) incoming transmissions on 467.550 with a PL tone of 103.5 and repeats the transmission (TX) at 462.550 with a PL tone of 88.5. I didn't even know what "split tone" was or even what "tone" meant, or carrier or squelch or hundreds of other little things you all take for granted. Since then, I realized that if the big, bad manufacturers like Midland, Kenwood, Motorola, and iCom can't even invite the public to learn more and provide useful content for each stage of the customer journey—Awareness, Consideration, Purchase, and Loyalty—the 2-way radio industry has much deeper problems and aren't there to help guys like me. As we get involved deeper into GMRS, there's little-to-no hand-holding going on at each level of knowledge. I ending up relying on the Ham community here and there and a guy who is basically a saint at a little radio shop in Phoenix, Arizona (hope Tim over at Procomm and the others at the nonprofit AZGMRS.org don't mind me giving them a shout-out). Edit 4/14/2020: By the way, AZGMRS made this awesome list of FCC-approved GMRS radios that they recommend. If you live anywhere near Arizona and are reading this, now would be a great time to become a member. Their repeater network covers some 100 miles around Phoenix with more and more repeaters joining the network (check out their sweet coverage map). But it's still frustrating. I wish a GMRS expert—presumably a manufacturer—would just come out and say exactly what a total newbie needs at each stage of their involvement or level of need. Two-way radio manufacturers should stop wasting time trying to sell, and start marketing and branding, which means educating the public about the 5 W's (Who, What, Where, When, Why [+how, +how much]) without trying to sell to them. Most new users don't know what they need because they don't know what's possible. For example, I wish I knew that manufacturers don't typically include the best antenna on their radios right out of the box. It took me over a year to realize that the best bang for the buck for a portable base antenna to include in my go bag is N9TAX's Slimjim and that Smiley Antenna makes the best bang for the buck antennas for hand-held radios (which by the way, everyone just assumes newbies are supposed to know that hand-held walkie-talkie radios are called "HT" for "Handy-talkie" and what a "QSO" is). How would a newbie know that the cheap Nagoya 771 "upgrade" antenna for Baofengs that everyone talks about actually isn't the best bang for the buck for the GMRS frequency band of 462–467? How would a newbie know that antennas work best when tuned exactly to what they call a "center" frequency that accommodates 5 Megahertz in each direction (+5 and -5 Megahertz) at the expense of hearing other frequencies? I learned the hard way that in order to properly install an NMO antenna mount on the roof of my truck, I would need a drill bit specifically made for drilling NMO antenna mount holes, and that yes, it is worth the money to do it right the first time. I'm still in the middle of learning how a "quarter-wave" or "5/8 wave" antenna works, the difference between dB gain vs. dBi gain, mic gain, antenna gain, because again, everyone seems to just assume I already know what all this means. I still don't understand what antenna "tuning" means and why you have to "cut" an antenna to "tune" it. Can I make my own antenna right now in a pinch with a copper wire in my garage? Ok, show me! How do I measure it or test it? What is SWR? Can I measure it myself? What do I need in order to measure it? Is one SWR meter better than another for my level as a newbie? Is there something I should learn to make it worth buying the better meter that opens up a whole new world of capability? Is it worth learning all that? This graphic did a great job beginning to explain what dBd gain means for those of us who know next to nothing about it, but now I need to go find out on my own and sift through a thousand webpages to find out if dBd is something new I need to know. Speaking of dB, I know that "dB" is a decibel, but is it the same as my stereo volume? Why do I see manufacturers saying that the microphone and cable have a dB rating? What is going on here? This is madness! We can Google things all day, but which info is true and correct and the most helpful? I think that the entire industry is sitting on a Gold Mine of consumers sitting at home for weeks on end who would love to buy GMRS equipment and communicate via GMRS to friends, family, neighbors, and other GMRS users. Whoever provides the most useful, relevant, and engaging content that stops making assumptions about what people know or don't know will win. STOP ASSUMING. START EDUCATING.

I think the biggest problem is, there are too many opinions AND most new users don't even know "what" they want to do. For the most part, many new radio users don't know what tech is the correct tech for any intended purpose. Until they get in and find out something they like and figure out how it will suit their needs, we wouldn't even know what advice to give. I have tried to help, though. I actually have a published article I wrote about the pros and cons of each common service, what they could potentially used for, and just a really brief overview of the science behind it. It was focused around off-road communications, but applies to everything. I can always share it here, but I haven't due to potential bickering.

While marcspaz's response if mostly accurate, signal reflection, while difficult to achieve, is possible. In the days when microwave was in common use for long haul links, mountain top reflectors were fairly common (see photo below). The same principal will work on UHF, IF the antenna is properly positioned at the right angle between the two transmitter locations. It is possible, though not likely, the water tower could act as a reflector. But, the transmitters would have to be well positioned and the antennas would have to be very high gain, probably a dish, and well aimed. So, I'd say if you can borrow two nice dish antennas, give it a try. But, don't expect too much. http://www.rfcafe.com/references/electronics-world/images2/radio-mirrors-communications-electronics-world-may-1969-2.jpg

The conceptual idea is sound in that professionals do have the knowledge to design a system for a user or even a class of user however, we all know there are no real "cookie cutter" solutions. While it would be possible to specify some equipment from a single brand that would fit the three (or is it four) classes of user; mobile, base, repeater and possibly the fourth being handheld not every manufacturer of these radios build all the parts needed for a complete installation with the exception of handhelds. Lets look at a typical home or base station setup. First you need the transceiver and a DC power supply with it as very few are AC powered. Next you would need the coaxial cable feed to the antenna and its mount with the antenna being the final piece. Here is where the most customization takes place. You need to know the distance for you coax run and how you will mount your antenna. There is some help on the mounting of an external antenna as the FCC has ruled that building owners and associations cannot deny you the right to install your antenna however they may make and enforce rules about how it is placed. The biggest issues any combo or kit recommender runs into are meeting customer expectations. While some expectations can be mitigated through different mixes of equipment, the biggest hurdle for the consumer will be the price of the kit and the performance of the equipment. Better equipment means a higher end price to the purchaser. That's why the homebrew solutions often work best. Being able to mix and match pieces provides the best path for any user. As different equipment becomes available the user can upgrade different parts of the install. A better transceiver may be able to use the DC power supply from the older unit along with the coax and antenna. The coax could be replaced with one having lower loss for the same distance or the antenna changed, each providing some improvements. There are just too many variables for a system designer to overcome.

I was doing some searching for anybody that may have tried the idea and stumbled across this gem. Got me a bit interested in the idea. https://az276019.vo.msecnd.net/valmontstaging/vsna-resources/microflect-passive-repeater-catalog.pdf?sfvrsn=6 While not exactly a water tower the idea is along the same direction, a passive reflector repeater.

Note. I obviously know nothing about your furnace. But, with modern high-efficiency furnaces, the exhaust gases are not very hot. In fact, a fan is usually required to use the exhaust fumes out the vent. So, if you do have a modern furnace, heat damage to the PVC is not likely to be an issue.

Well, kt seems you have actually answered your own question. Since rooftop antennas are allowed where you live, the real issue is getting the antenna mounted on the roof. It is understandable you do not want to go climbing around up there, so why not hire someone to do it for you? Mounting the antenna is the simple part. There are all kind of antenna mounts that might work. But, there is one very simple approach you can try just to test: Mount your candidate antenna, I'd start with a simple ground plane 1/4 wave, on one end of a 10 ft piece of 1" PVC (Sched 40 is good). Then, about 3 or 4 feet up from the base of the PVC pipe, attach something to the pipe to increase its diameter so it won't fall in to a plumbing pipe vent. Then, just drop the pipe into a vent pipe. Done. Sort of like this (I think they actually drilled a hole through the mast and one side off the vent pipe and used a bolt. But, you could use a pipe-clamp and some pieces of bent coat hanger just as well)....

Jsouth. I would suggest you pick up a copy of the ARRL antenna handbook. It will give you a great insight to how your antenna works, and what you can do to improve both transmit and receive. It also will give you the knowledge you need to build your own antenna. Antenna for UHF 460-470Mhz can be easily made from material obtained at Homedepot, less a few small items you will need to purchase online. The high Dbgain of a directional antenna, it is amazing what can be accomplished. Always remember in most cases the higher you get your antenna the better.