dosw

I'm not saying your use case isn't legitimate. I'm aying there's a lot that can be learned by investigating what others have already learned as they work the 10m, 2m and 70cm bands. I think that you're asserting that you need to know for your specific situation which will work better; CB, MURS, GMRS, at an equivalent power. For that, sure. You're going to have to set a GMRS radio to 2w, and set a MURS radio to high power of 2w, set a CB to 2w if possible, and do your comparisons. But in a broader sense you're asking questions that may be answered by looking at the body of knowledge developed over decades of amateur experimentation with 10m and 2m and 70cm. So I'm not suggesting "Go get your amateur license and be a ham." ...you may already be there, but that's not relevant. I'm just suggesting that the findings of others in those bands would apply to answering your question in general ways, though probably not specific to your neck of the woods.

SDR software allows SDR owners to set up an SDR server that can either be the back end of a web page (websdr.org, for example) or can be connected to by SDR++ itself. I could connect SDR++ to any SDR server on the web that allows me to access it. And sites like websdr.org aggregate sites that provide web interfaces to networked SDRs. Similarly, there are websites online that allow users to listen to radio scanners in varioius geographical regions. Is there now a problem with this paradigm with respect to GMRS? If a website wanted to expose SDR or scanner feeds in various regions, is that now against the rules? Maybe it always has been. Let's say, for a moment, that it is permissible to expose an SDR feed or a radio scanner feed over the Internet. If an SDR feed from Atlanta is set to GMRS 462.7000 with PL 127.3 and that is available to be listened to over the Internet, it's not repeater linking -- people can't respond, they can just passively listen. And if that is okay, a feature of *this* site (or some site) could be to allow repeater owners to provide a link on their repeater's information page, to an SDR, scanner, or radio that is passively listening to that frequency in their area and feeding it through the link. Is the FCC saying, now, that is against the rules? Because if it is, it's the one radio service where that's suddenly a problem. OR all online SDR and scanner websites are in violation, across all radio services they feed, except for amateur bands. I'm just trying to think through the ramifications, and figure out what is allowed, and what isn't.

There's a wealth of information available on 10m propagation, and on 2m propagation, since they are both amateur, ham bands. Probably a lot more you can read up on than if you search for CB vs MURS propagation. I'd start there. CB is 11 meter, ham has 10 meter. They're close enough to be very similar. And with ham 10m, you'll find a lot of information about SSB, FM, and AM: SSB is usually at 28.3MHz to 29.3MHz. AM is usually 29MHz to 29.2MHz. And FM is usually at 29.6MHz, all within the 10m band. And in 2m, you can find allocations for SSB and FM, including weak-signal work. Each of those categories is a world of pet projects for some people (this time I'm using "some people" in a good way, I hope). Consider MURS approximately equivalent in propagation characteristics to FM simplex over 2m. And consider CB approximately equivalent to AM and SSB in the 10m band.

It would do fine at 5w, just like a 2m ham does at 5w. There's plenty of dialogue online about 2m ham at 5w. But it's an unlicensed set of channels intended for short range use. Increasing power would potentially interfere with adjacent frequencies in the MURS neighborhood. There's not enough difference in propagation between VHF and UHF for the FCC to carve out a new set of frequencies to do pretty much exactly what is being done with GMRS, and charge for a $35 license, when we already have GMRS. The VHF spectrum is crowded, so it's an uphill battle to make it happen in a GMRS similar fashion. Amateurs get to leverage the difference in propagation because they jumped through the test hoops and paid their fees. I don't think MURS will or can go to higher power as an unlicensed service because of the impact to paid license neighboring frequencies. And there's just no room for repeaters with only five channels at funky offsets from each other with some allowing wideband and some allowing only narrowband.

I've done some research into ground planes, and it's entirely possible I've got some of this wrong, but here's what I understand: A good ground plane will provide a radius that is at least a quarter wavelength. So for GMRS, that would be at least 6.4" radius. Ground planes should extend in all directions along the horizontal plane, or at a downward diagonal, depending on the antenna / design. If the ground plane isn't a contiguous surface it is often set up as a series of rods. Two opposed rods would have better propagation lobes along the plane of those two rods, and worse at 90 degrees. Three rods is fairly common. Four is also very common. There are diminishing returns for ground plane rods beyond four, though there's always a non-zero positive impact to adding more symmetrical rods. There's also a diminishing return for making the rods longer than a quarter wavelength. But at less than a quarter, the lobe tries to curve around the end of the rods. Asymmetrical ground planes may have a somewhat truncated propagation lobe in the shorter directions. In your case, the propagation lobes may try to curve around the rack's pipe, for example. The point being, I don't think a roof rack's beam is ideal as a ground plane. But ideal may be the enemy of good enough. However, given that there are pretty good "no ground plane" antennas out there, you may be able to at least select one that doesn't force as much compromise. For my RV I use a Laird TE B4505CN ("N" means no ground plane). I had to trim its bottom whip element for GMRS, but product literature helps by suggesting where that sweet spot is. And as I mentioned in another post here recently, it's very easy if you have a VNA instrument (NanoVNA). Someone who doesn't want to buy measurement equipment could probably find someone on a local GMRS repeater willing to spend a half hour helping measure and cut. But for the B4505CN the manual recommends the appropriate length for GMRS. It's a 5.1dbi antenna.

Since I'm a gadget addict I got a NanoVNA a few days ago, for about $59 through Amazon. It came with two SMA-Male to SMA-Male cables, an SMA Female to SMC Female adapter, and three "standards" (open, short, and 50 ohm load), as well as a little stylus, and a lanyard with a guitar pick on it (presumably to use in place of the stylus). I wasn't expecting a lot, but I have to say, this thing is pretty cool, for the price. It's not professional-quality analysis gear, but for a hobbiest it's great. The first thing you should do when putting it to use is to calibrate it for the band you wish to analyze. You use the "standards" that it comes with to perform the calibration. I followed that up by putting an antenna on it, and on my RTL-SDRv4, and verifying its signal generation was accurate. It was close enough without any tweaking. Next, I used it to test some antennas. At first I just confirmed that the MXTA26 is very well tuned, out of the box, centered on 465MHz. And then I put the NA771G on it: In that graph, you can see that I have it configured to scan the range from 420MHz to 480MHz. I've set a marker at 462.2MHz just by dragging it into place with the stylus. I could have set it more precisely through the menu. The S11 LOGMAG represents return loss. The lower the dip on the graph, the better (less reflection/return means more signal is radiating, which is what an antenna is supposed to do). The blue line here indicates SWR. And as you can see for the NA771G, it is 1.055:1 at 460.2MHz. At 480MHz (I don't have a marker set there), it was about 1.27:1. The green curve is the Smith diagram. And the purplse is the |Z|, coming in at 52.2 ohms at 460.2MHz. There are many graph views, I selected four of them. But they include logmag, phase, delay, smith, swr, resistance, reactance, |Z|, polar, linear, real, imaginary, Q factor, conductivity, susceptivity, |Y|, series C, series L, Parallel R, Parallel X, Parallel C, Parallel L ... most of which I don't comprehend. One thing that I learned was how great it is to be able to look in realtime at the various curves. It made it really easy to observe changes as I added and removed the ground plane rods from my Nagoya GPK-01 (Ground plane kit) when the antennas were mounted on a camera tripod where there's no good inherent ground plane. And it was really useful to be able to observe what happens when I take a half centimeter off of an antenna. In the case of the NA771G, if one were wanting to tune it (which you can't), you might decide to subtract a fraction of a centimeter from its length, and you can see that on the chart. I used the SWR and Logmag curves to tune my Laird TE B4505CN antenna, for example, as I recognized its SWR dipped a little further to the left of the GMRS band. By trimming its base element down to about 10" (taking about 2cm off), I moved the dip to 465MHz. And knowing which direction to go was really only possible by looking at these curves and observing what they do as I move the element in and out a little with its set screws. I also tested the pass-through mode using a VHF/UHF diplexer, verifying the cutoff ranges for each of the diplexer's ports. A good feature is the ability to plug it into a computer and command the device, and observe its graphs, right on the larger screen of a computer. On my Linux laptop the NanoVNASaver application was already available for Ubuntu install through the apt and apt-get package manager tools without having to compile from source (one dot-release behind the Git repository). With the free NanoVNASaver software I can specify a scan range and set up multi-pass averaging. And the software can step through a scan range to achieve much finer resolution than the device natively supports. For example, if I use the native 101 data points the device supports to scan from 144-480MHz, that's one sample every 324kHz. Not very good resolution. But if I tell the external software to take 3240 samples, it will step through the range 100 samples at a time, and get me resolution finer than I can reasonably use on a full size monitor. Another interesting option, through the NanoVNCSaver software, I'm able to see feed line length and attenuation. I can test a 50 foot run of LMR400, and a 50 foot run of RG58, and see loss per frequency. That's really interesting information for a hobbiest. Some negatives: If you're completely in standalone mode (no computer), it's only got 100 sample points in a given scan. So if you're trying to optimize a dual-band antenna, you would want to concentrate on 2m, and then on 70cm, going back and forth one at a time, rather than trying to show both on the screen while tuning an antenna. This is where using a computer with a much higher sampling rate is important. Its screen it pretty tiny, too. Having spent the $59, I kind of am on the fence as to whether I should have spent $89 to get the larger screen. On the other hand, adding a computer to the mix, even an inexpensive low-powered laptop, the screen becomes irrelevant, and sample-points become virtually infinite. Another negative is the lack of instructions. It comes with a single page showing where to find the various menu options, but no other explanation. It took some youtube videos and online reading to figure it out. And without a microSD card you're missing out on being able to save screenshots (though you can take a screenshot through the computer's software), and limited on number of calibration configurations you can store. But most of those shortcomings can be overcome with an external computer and/or a cheap microSD card. For my purposes this device is fantastic. With the Surecom SR102, I could see the SWR of a given antenna setup. With this device, I can see which direction things need to go in tuning antenna setups. And I can verify a diplexer is working as intended.

You are probably using simplex. If you both are using tones, you should both set Tx and Rx, same tone. Think of Rx tone as filtering out any transmission that doesn't have that tone. Think of TX as providing a tone that the recipient can listen for as he filters out everything that doesn't have the tone.

Power: The radios I've seen all connect their power either through a cig adapter (Radios outputting 25w or less) or using some sort of relatively easy to find plug connector so that you can remove them and leave the primary wiring still routed through the firewall to the battery (fuses, of course). So whatever that connector is, you'll want two of them; one to leave in place in the car, and one to leave connected to your 13.8v DC power supply at home. Or get a lower powered radio that can work with an easy to remove cig adapter. At home you'll need a cigarette receptacle on your 13.8v DC power supply. Antenna: It doesn't take much time at all to unscrew a PL259 connector. Keep an antenna mount on your vehicle with a cap over the NMO mount when not in use. And have an antenna mount at home. At home you might go with a more stationary antenna like the Tram 1486, whereas on the vehicle you would probably want an NMO whip antenna. Mount: Some of the cigarette plug radios have mounts where you can slide it in and out of the mount quickly and easily. You would probably order a second mount so that you have somewhere to slide it into in both the vehicle and at home. The swap would take just a couple of minutes. I do the same, with a Midland MXT-275; I have a mount for it in my boat, a mount in the RV, and a mount in my wife's car. We just put it where we need it. I never need it to be in more than one of those places at the same time.

Correct. There are many well placed 2m and 70cm ham repeaters in Utah County. I was suggesting that getting to know people in the ham community may facilitate a conversation on getting a GMRS repeater set up at one of those well placed ham sites.

Serious question: is there a grease you would use to help prevent water intrusion?

My MXTA26 hasn't become waterlogged like that either. However, I found moisture in my MXTA25 once. But after giving it ample time to dry out it was fine. I have gotten into the habit of using some diaelectric grease on the bottom o-ring and NMO threads of antennas. And I think I even put some into the whip hole of my antennas, to help prevent water intrusion. Dielectric grease is non-conductive, but it also doesn't prevent connections from being made. And I've tested with the SWRsometer to verify that I didn't suddenly drive the SWR through the roof by applying the grease.

It's really not a big scary thing to say, "This is ABCD123 doing a radio check." And you can append to that transmission, "I've got someone else listening, so I don't need a response" or "If anyone's listening, I'm also looking for a signal report." People will often respond, and usually politely, even enthusiastically. The worst that can happen is someone comes on and says, "Stay off the repeater." At that point, you cross that one off your list and move on. Either way, you learn a lot more by doing a real radio check than by just kerchunking repeaters. I don't rag-chew over GMRS or any other radio. I don't even rag chew on the phone. I do post too many responses in forums though. But even so, I'm glad when I get a response telling me how my signal sounds. I've never found anyone to be rude about it.

This has really gone too far. There are surely zero enforcements where the FCC checks receipts of grandma two miles away from her grandson, the license holder, to see if she owns the equipment she's using, and to see if her use is under direct control of the license holder. For that matter, if she and her radio were under direct control of the license holder, they very well wouldn't need to be talking over GMRS.

Yeah Capital and Ogden repeaters, and more recently West1 get some socialites on them. Promontory occasionally too. But Capital particularly. Not all day, but when they do light up it's hard to break in with a question, and it can go on for 90 minutes. I've never said more than three sentences to a stranger on a repeater, but it's pretty easy to get a response to equipment and propagation tests. As for FRS nets: Some local church groups run emergency preparedness simplex nets within their neighborhoods, and those tend to be a mix of GMRS and FRS users checking in.

Maybe it's a Utah county problem. In Salt Lake county I can hit Capital (20, Ensign Peak), West1 (15, Oquhirs), East1, East2, Ogden, Promontory, Stansbury (if I'm in the northern part of the county), Bountiful, one in Sandy (GMZ01). And a couple others I don't use because they're rather short range. Capital, West1, Promontory, and Ogden provide very good coverage in the valley, foothills and benches. I hear nets on Ogden, Promontory, West1, and Capital. There is a simplex hobby net Sunday at 8 (can't remember the channel), and neighborhood self preparedness FRS/GMRS simplex nets on several channels Sunday afternoons and evenings. In 2m and 70cm I hear nets and traffic on repeaters in Draper, Lehi, Farnsworth Peak, and Ensign Peak, as well as some very short range ones in Sandy. I don't listen in Utah County much, though. If there aren't enough repeater options in Utah County, you might approach one of the 2m or 70cm owners and ask to work together getting a GMRS repeater on their ham tower.

The best way to monitor that I've found is to plug your radio into a VOX recorder or a computer running Audacity in VOX mode. Come back the next day and listen. Write down call signs, and if the repeater uses more identification you can also play that into software to decode the Morse, which will give the repeater owner's call sign if you don't already know it. But most importantly you'll know if anyone is using it, and can see how they interact: is it a rag chewing group, is there a weekly net, etc.

Four days? Just be patient. Repeaters are typically privately owned and represent the work and money of a hobbiest who may have other hobbies, other interests, other things vying for his time. If I were a repeater owner, and if I were to take a vacation for ten days and don't respond to an email from mygmrs about someone I don't know wanting access to the repeater, would that make me inappropriately slow to respond? Give it some time. If I didn't respond to someone in four days asking for something that I'm giving away for free, and the person got impatient I'd probably be inclined to say "Nah, this isn't going to be a good fit."

So we're saying that if I take a mobile GMRS radio and hook it up to an external antenna and an external power supply at my desk inside the home, which, I think, makes it a base station, at that point I'm not allowed to use it to hit a GMRS repeater?

Probably should have started a new thread, since this is a new question largely unrelated to the original thread, that hasn't been active since 2022. But I'll try to answer: If you hear the squelch tail it means you opened squelch on the repeater, which means you are at least getting enough signal through for the repeater to hear your PL tone or DCS code. Others should be able to hear you. Squelch tail is the sound the repeater makes when it is transmitting, but not still receiving a signal, but hasn't had enough time to stop transmitting yet. Here's the sequence of events: You key up. Repeater senses a transmission on its frequency. Repeater detects that your PL tone is the one that it requires to open squelch. Because it detected your tone, the repeater opens squelch and listens to you, while at the same time retransmitting your signal (which is coming in on a 467.xxxx frequency) out to everyone listening on the 462.xxxx frequency. Other peoples' radios hear a transmission on the repeater output frequency. Other peoples' radios decode the PL tone and open their squelch. You talk for awhile. You release your key. The repeater stops receiving a signal, but is still transmitting for a brief moment. The repeater notices the signal went away and stops transmitting. Receiving radios notice the signal went away and stop receiving. The squelch tail people hear is step 9 through 11. The repeater is transmitting for a brief moment without any input, so there's a short moment of some subdued static, your radio's squelch stays open during this time because the PL tone and carrier signal strength are holding the radio open. If you hear this, it means you hit the repeater. Now, why you can't hear yourself... why were you expecting to hear yourself (this is an actual question). Is it because (1) You think you should be able to hear yourself like you do on a telephone, or (2) because you had another radio nearby that was receiving? If it's "1", that just doesn't happen. GMRS radios operate on half-duplex while working repeaters. Telephones use full duplex. If it's "2", that's usually because the second radio is so close to the transmitting radio that its reception it totally overwhelmed by the power coming out of the transmitting radio, to the point that it doesn't hear the distant repeater's transmission. Think of it this way: If someone shouts at you from 100 feet away in a quiet setting you will hear them. If someone shouts at you from 100 feet away while you have your car stereo blasting at full volume, you won't hear them. The person 100 feet away isn't putting out any less volume, it's just getting lost in all the noise. The usual solution is to have someone take that other radio a tenth of a mile away and listen there, so that your transmitting radio's RF energy isn't overwhelming the listening radio's receiver.

I stand corrected. Apologies on that front.

A: The FRS channels predated GMRS channel numbering. When the services combined on frequencies, the frequencies were layered in. Additionally, the 15-22 frequencies, and the repeater input frequencies are the "mains", while the 1-7 and 8-14 are the interstitials; they are intentionally lower power (5w or 0.5w depending on the channel) so as to have less potential for interfering with the mains. B: Every FRS and GMRS radio I've used (Motorola FRS radios, Midland GMRS handheld radios, Motorola combination radios from before the rule change, Baofeng GMRS radios, Midland mobile radios, and Retevis mobile radios) use the same channel numbering. The earlier FRS didn't have channels 15-22. But aside from that the numbering has remained unaltered. You'll have to demonstrate model numbers that shipped with incorrect channel numbers per frequency. Or did you alter them with CHIRP? C : Yes, GMRS and FRS use all the same frequencies, except that GMRS adds the repeater input frequencies, as well. What you get by purchasing a GMRS license: A call sign. The right to transmit on a GMRS radio Repeater capability 5w instead of 2w on channels 1-7 50w instead of 2w on channels 15-22 50w instead of no right to transmit at all on repeater inputs. Right to use external antennas (FRS is built-in antenna only) Right to use mobile GMRS radios (FRS is handheld only) on channels 1-7 and 15-22, and repeaters. Right to use base station GMRS radios (FRS is handheld only) on channels 1-7, 15-22, and repeaters. Full access to all of these capabilities for your entire family (the license is family oriented). D : The NFM (narrowband FM) setting in Chirp sets the radio to 12.5kHz or less. The FM setting (wideband FM) in Chirp sets the radio to 20kHz or less. You will also notice from your chart that the channel spacing between 15, 1, 16, 2, 17, 3, 18, 4, 19, 5, 20, 6, 21, 7, 22 is only 12.5kHz. 15, 16, 17, and so on are all spaced 25kHz apart, but the interstitials are also spaced 25kHz apart, and sandwiched directly between the mains. This is why they're called interstitial frequencies, and why they are limited to lower power (5w for 1-7, 0.5w for 8-14); as mentioned earlier, to reduce interference with the mains.

For those who don't want to bother with downloading his powerpoint and fixing all the fonts, here's the slide he posted.

Why is this posted as a question, and wouldn't it be better to just post your situation, and how you solved it, so that people can learn something without having to DM you?

What equipment is used in testing that current draw?

That's what I was eluding to with my mention of "...honor system." Out on a fishing trip away from a populated area, talking to your grandson who is on an FRS.... you're one step ahead of the game already just by having your license.