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Though I've mentioned this as a side item in various posts, I wanted to take the time to create a specific post to spotlight my favorite youtube channel for GMRS info, including equipment. I'm speaking of NotaRubicon Productions. The owner of that channel is a down to earth guy by the name of Randy. His channel has good things going for it: + Good Production. Good lighting. Good mics. A sense of humor. A born-to-do-this delivery ability. Aspiring YT channel stars, take note. + Good Information. The good production attributes mentioned above can help bring people into a channel and make them want to return. But that is not enough. There has to be relevant information delivered to the point. Randy does this. It's obvious that manufacturers are aware of him and the fact that he is an influencer. When Randy gives a thumbs up for a radio model, buyers snap them up. When he mentions problems with newly introduced radios, manufacturer's fix them fast. I have no connection with Randy or his YT channel. Just wanted to share a good GMRS youtube channel for those interested.

Cables have loss. The bigger the loss along the run of the cable, the less signal goes out and comes in. Also, the more the loss the better the SWR. The longer the cable, the bigger the loss. Coax loss chart: https://www.w4rp.com/ref/coax.html Coax loss calculator: https://www.qsl.net/co8tw/Coax_Calculator.htm There are number of thread here discussing cables, loss, SWR, whatnot.

Thanks for tracking down and posting the requested link. I did not get around to it this morning but observed you had already done so. While the linked report out did focus on HT testing, mobile/base units have been measured during my play since then. Of the sensitivity numbers I mentioned earlier, the radio with the least basic sensitivity is a 50w mobile. Thanks again. Michael WRHS965 KE8PLM

In general it's good to plan on UHF being line of sight for reliability purposes. With that said, VHF and UHF can go beyond what you can see pretty readily. It's not going to bounce off the atmosphere (short of rare atmospheric conditions), but you do have refraction and reflection within the environment. If you're standing on a perfect marble - yup it's going to go into space like you mention. Same for the most part with rolling hills or paths over sustained topography; it's what you can see for the most part. Down in my neck of the woods (Tucson), there's a lot of isolated mountain ranges. If you're on the other side of a mountain and the topography is such that the top of the mountain forms a somewhat clean 'knife edge' between you and another station roughly perpendicular to your path; the signal can actually bend over the top pretty easily and you can get a pretty appreciable signal even thought here's a huge mass of rock in your way. Likewise, UHF can also reflect on large planar-ish surfaces such as rock faces. I have a few repeaters I can hit/hear from Phoenix at my house decently (over in the northern end of Tucson) even though I have a small mountain range in the way. When I point the yagi at Pusch ridge (a large rock face/cliff formation about 15 miles from my location), they actually come in with a solid signal, if I try and point it at the direct path to the repeater, it's nothing but noise. Plotting the path on Google Earth actually revealed that this rock face is at almost a perfect angle to act as a reflector in this direction where both my station and the repeater have line of sight to it, but not between my station and the repeater directly. This has actually proven to be a reliable tool for me for hitting those machines - works every time.

Received my Radioddity DB20-G yesterday and the external speaker today. They must maintain their stock with Amazon as that is who did the delivery. The outer box is different, and the mic and radio are badged with Radioddity, and at powerup, the LCD displays DB20-G. Otherwise it's the same as my AT-779uv. I even just programmed the same file into it as what I created for my 779uv. I won't know until Monday if this one has a problem with that repeater, but I do know myRadioddity I just got has a little more RF output power vs my 779uv. VHF is right at 20W, and UHF at 17W vs both those #'s being 2W lower for my AT779uv. I'll chalk it up to production variability, and 2W is not going to make a difference. It was just interesting to see. Also, fwiw, I realized today that I do in fact own a very accurate signal generator that goes down to sub hertz (HP 3336C). Using it to create PL tones, and then feeding it into my HP 8657B, I should be able to measure at what PL level both of my 779uvs need to decode it, and then compare that to other radios I own. Might try that tomorrow.

Another channel worthy of mention is Ham Radio 2.0 He does mostly ham videos but is engaging more and more into GMRS.

Yeah, some members are strong Motorola devotees for exactly that reason...they hold up well in high rf environments. what's the term @gman1971 uses....fire breathing RF monsters?

These results are about what I'd expect. That's not an especially hostile/dense RF environment. Given that only about a half-mile of reliable coverage was achieved, I believe there was an LoS issue, probably caused by terrain. There's no cheating the laws of physics - barring a serious sensitivity issue with the Chinese radio, it will perform about the same as the Motorola in a low-noise-floor environment. Put it in an environment with a high noise floor and it will struggle. Another interesting point - 0.5 square miles of full quieting coverage was achieved compared to 1.13 square miles of copyable but noisy coverage. A digital mode such as DMR, P25, or NXDN would 'clean up' the audio in that 0.4-0.6 mile band, more than doubling the area in which noiseless communications are possible. Beyond that, it will also be spotty - P25 doesn't defy the laws of physics either. Just something to consider, as digital modes are normal and accepted in the amateur service. (I also know of a couple digital repeaters in GMRS, operating under FCC experimental authorizations).

@WRKC935 This is also the argument (both GMRS/HAM/LMR) when one claims they want to put up a "high power repeater" or "add more power" to their repeater. The question is why? Thinking logically, at the same antenna elevation, 99.99% of your users are going to be 50W or less. It doesn't help if the repeater can get out 1000 miles your users can't use it. Most repeaters utilize good antennas (9-12db gain), and after you figure your cable losses, fittings, jumpers, duplexer, etc. you end up at a break even point, or a small amount of gain. Anything between 100W and 50W to the feedline ends up with a nearly identical in/out range and decent coverage, provided the antenna placement is decent. For GMRS, your primary concern is build something that the duty cycle won't burn up.

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.

I own the ham version, btech 25x4, and the colors do mean that the squelch broke on a given line (it did pick up something). I bought my unit a few years ago, so my firmware likely has bugs as the color of a line does not return to red if the transmission goes away. Note, the radio won't go looking at the other channels if you're actively receiving on a given one. Only when the one that it's tied up on goes away, will it then watch the other channels.

I enjoy Randy's reviews on his channel