Lscott

More info on passive repeaters. Passive Repeater.pdf

A different MPPT controller brand might be better RF noise wise. The one I linked to the manufacture claims it doesn't generate the RF hash others do.

That's possible. There are such things as passive repeaters, nothing more than a huge sheet of metal acting as a reflector. The mountains could be doing that. What might be more likely is some diffraction effects. Light waves, and RF waves, will experience diffraction when passing a sharp edge. In your case it could be the ridge at the top of the mountain. Enough energy diffracted downward to make communication possible. Warning only math geeks should try to read this. https://apps.dtic.mil/sti/pdfs/AD0117276.pdf This isn't as bad and the illustrations make the explanations easier to understand. https://www.ihe.kit.edu/img/studium/Wave_Propagation.pdf

I think that's the replacement for the old -42WD type. KMC-42WD.pdf

A similar speaker mic is the KMC-17. I have a couple of those and my buddy says it sounds good on the air. It might also be cheaper than the -45. KMC-45.pdf KMC-17 Revised.pdf

Well it's the difference between a 1/4 wave long antenna verses a 1/2 wave long antenna. The minimum length antenna to radiate RF is a 1/2 wave length long by theory. Since a 1/4 wave length antenna is "missing" the other part, the absent 1/4 wave length, it has to be made up for some how. That's where the ground plane comes in, it doubles the antenna length so it looks like it's a 1/2 wave length long to the transmitter. To make the idea simple to understand place your finger against a mirror so it's perpendicular to it. You'll see immediately the reflection of your finger touching the end of your real one. That's basically what the ground plane does for a 1/4 antenna, it "mirrors" the other half of the antenna so it looks like it's really a 1/2 wave length long. With a 1/2 wave length antenna you have a choice where to attach the coax cable, in the middle or at one of the two ends. If the coax is attached in the middle the impedance is around 70 to 75 ohms more or less. That's a reasonably good match to a 50 ohm coax resulting in an SWR of about 1.5:1, which all most all radios will have no issues with it. For a vertical antenna the most convenient place is on the end. For some complicated reasons the impedance is far higher than the 50 ohm coax cable. For those antennas a matching section in built into the base. An example is the common "J-Pole" antenna. It's really a 1/2 wave length antenna with a 1/4 wave parallel transmission line matching section on the end. The feed point is selected such that the ratio between the voltage and current is 50, which is the required value for the 50 ohm coax. If the coax feed point was exactly on the shorted end the voltage would be zero, resistance = voltage/current, so the impedance would be zero. At the other end the current is nearly zero, the un-terminated end of the one element, thus the impedance is extremely high. Thus the match point must lie someplace between those two points. This is about as simple of an explanation without getting deeper into the theory.

Have you considered swapping out the simple PWM charge controller for a MPPT type? In theory it should allow you to capture more energy and store it in the battery. With large changes in solar radiance and panel temperatures this will make a noticeable improvement IMHO. These controllers seem to work rather well. For about 100 watts of panel power a 10 amp controller would be right for your application. https://sunforgellc.com/product/gv-10/ Which solar charge controller PWM-or-MPPT.pdf

This is likely the same radio but with different firmware. https://www.miklor.com/COM/Review_GMRS-50V2.php https://www.miklor.com/COM/Review_50X2.php The problem with most of the cheaper Chinese radios is the receiver section. They get de-sensed easy in strong RF environments and the selectivity can be poor. Most radio users after a while will understand the receiver is what really counts. Given a choice between more power or a bullet proof receiver I would go with the better receiver.

Since this is just "theoretical post and for speculation" and Ham related. For GMRS I'm sure you're well aware of the rules so it's up to you what you do. I'm not aware of any "Ham" single or dual band radios for VHF/UHF that will do 100 watts. The most common power levels are 40 to 50 watts, with UHF generally being the lower of the two. Now for commercial mobile radios there are some that will do 100 watts. You'll likely end up spending a huge pile of shinny coins to get one. You might be better off getting something in the 15 to 25 watt range. You can find these at relativity affordable prices. The following is an example of one I have. While it's an analog/digital radio I didn't complain about the price, It was free, pulled out of service after a short while, never reused, and scraped off the books by the original agency that had it. https://forums.mygmrs.com/gallery/image/250-nx-820ghjpg/ The lower power radio you can later add the amplifier if you find it necessary. If your operations will be primarily through repeaters that's likely all you'll need. When I first got licensed I used a dual band HT on low power running into a Mirage dual band FM amplifier, around 35 to 45 watts depending if it was UHF or VHF. Never seem to need more for repeater use operating mobile. Later I had an Icom IC-706MKIIG. I almost never ran more than 20 to 25 watts on it either. Generating the kind of power you want at UHF isn't that easy and it's not going to be cheap. https://www.dxengineering.com/search/part-type/vhf-uhf-amplifiers/rf-output-maximum-power/100-watts Most people coming to GMRS from a CB background are hung up on the power output myth, the more the better. At VHF and more so at UHF the communications are LOS, line of sight, the radio waves don't bend around obstructions in the path very well. To give you an idea of just how far you can reasonably expect is look at a mobile antenna on a Jeep for example up maybe 6 feet. The range to the radio horizon, square root of antenna height above ground in feet times 1.4 gives range in miles. sqrt(6)*1.4 = 3.4 miles https://www.hamuniverse.com/lineofsightcalculator.html If the other vehicle is about the same then it's the combination of both, about 6.8 miles. Running a huge amount of power won't extend this much. Some of the other posters here have done the experiments and have come to about the same conclusion.

Each employee, including you, would be required to have their own GMRS license and comply with all the regulations including the ID one. As a business owner you can't get a license for your business, that was eliminated with the rule changes in 2017, and hand out radios to your employees. If that's too much to deal with then just go and buy a bunch of FRS radios. Most of the same regulations apply that you see for GMRS. The big differences are the radios are limited to 2 watts on most channels, no repeater access and no ID/license requirements.

What model was that? I'm still looking for a mobile dual band antenna, 1/2 wave - ground independent, that's usable on MURS and GMRS as well as the Ham bands. I thought the Diamond SG7500A would, but it isn't going to work based on my tests. On the Ham bands it looks OK. https://forums.mygmrs.com/gallery/image/283-sg7500a-swr-scans-2jpg/

That's the usual reason, you're correct on that point. FM receivers incorporate a "limiter" stage for the sole function of eliminating any amplitude modulation in the RF signal.

Wrong. I've operated VHF and UHF FM for over 20+ years. It doesn't work that way. If you want to talk about SSB on 2M that's a different story. https://en.wikipedia.org/wiki/Frequency_modulation

The radios we use employ FM, frequency modulation. In other words the transmitted frequency is varied to convey the audio information. The amplitude of the transmitted signal, power, is not used to convey any audio information. This is why you see references to wide-band verses narrow-band on these forums. What is being referred to is how much the transmitted frequency varies, called deviation, for a given audio signal level. The wide-band can vary the transmitted signal by as much as 5KHz, while a narrow band signal will only vary by 2.5KHz. If we use wide-band on transmit to communicate with a narrow-band radio the audio will sound very loud and likely will be distorted. The reverse case a narrow-band radio transmitting to a wide-band radio the audio will sound very weak, low volume. This is why it's important to ensure that all radios are set to use the same bandwidth, deviation, and thus the FCC's comments you got.

The power level has nothing to do with the audio volume when using FM for communications.

If you have a GMRS license there is no requirement you have to use 2 watts or less on 1-7 and 15-22. That ONLY applies to FRS radios. GMRS radios can use up to 5 watts on 1-7 and up to 50 watts on 15-22, and that includes when talking to FRS radios. FRS-GMRS combined channel chart.pdf

That's not a "requirement" as such. It's in the rules that GMRS radios must use narrow band FM on channels 8-14 and no more than 0.5 watts. This is the exact same technical requirements for FRS radios. The FCC rep likely mentioned the above because the two radio services would be compatible on a technical level. You can legally program your GMRS radio to use narrow band FM on all channels thus you can use any of the 22 to communicate with FRS radios. The radio I use, Kenwood TK-3170, has "zones" which are logical grouping of memory channels. I have one zone programmed for wide band when talking to other GMRS radios, and another zone with the same channels programmed for narrow band to talk with FRS radios. Since the radio can't be turned down to 0.5 watts, minimum is 1 watt, I don't use 8-14 to talk with FRS radios.

My understanding was it only occurred in the vicinity of the ATV site. Once the affected systems were far enough away they were OK. I guess what it came down to the designers didn't do enough research when selecting what frequency, band, to use for their product. The radio spectrum is very complex with the same band being used for different purposes, shared, and sometimes they don't play together very well.

Have you considered some less expensive radios than the above? There are other analog only commercial radios that will take a beating and keep working. Myself I carry a Kenwood TK-3170. You can can find them for very reasonable prices used and it has Part 95 certification too. http://www.swscomm.com/kenwood/TK-2170_3170.pdf There is also a version with trunking, TK-3173, which you won't use on GMRS, but programs the same as the 3170 and uses the same cables and software. http://www.swscomm.com/kenwood/TK-3173.pdf

These comments point out an interesting issue if I understand things right. Most, if not all, electronic products are sold with FCC Part 15 compliance. A section in that part basically says the device accepts all interference even if it causes the device to malfunction. If it does then contact the manufacture. Now try to explain that to your neighbor when they says it's YOUR problem to fix. Nope, so long as your radio meets all FCC certifications. Another reason to be sure your radio is Part 95 certified. A case in point. Years back people were experiencing car alarm failures around the I-75 and 14 Mile intersection close to where I work. The FCC was notified. The issue was traced to a Ham ATV transmitter on top of a tall senior apartment building a couple of miles west of the location above. The FCC shut the site down while they did their investigation. They found everything complied with all technical requirements and allowed the site to resume normal operations. The ding-dongs had put the alarm system on the 70cm band. I believe there is a provision in the rules for this were the equipment manufactures can use 433MHz. https://www.edn.com/using-433-mhz-for-wireless-connectivity-in-the-internet-of-things/ The head guy at the alarm company asked one of the site's equipment owners in for a talk. He asked how much power they were running. The answer was about 100 watts. Then he asked the second one. How much CAN they run. The answer was 1500 watts. The owner I was talking to telling me this story said the alarm company guy almost crapped his shorts. Then he proceeded to tell me another story about how Chrysler, as it was known at the time, had their tire pressure sensors malfunction. They were running tests on them and had the problem again in about the same area. In their case they figured out the cause and understood it was their problem to fix.

I'm guessing the dummy load looks something like this? https://www.amazon.com/XRDS-RF-PL259-Male-RF-Dummy/dp/B08QR9RQJ3/ref=sr_1_13?keywords=XRDS-RF&qid=1678988619&sr=8-13 I wouldn't worry about the resistance reading of 49 verses 50 ohms. There is a tolerance on the accuracy of the dummy load and the meter itself that likely accounts for the difference. Dummy loads also have a frequency range they are designed to work over. High quality ones may even have a datasheet showing the expected match verses frequency. The one you have may just be at the edge of the range, but without further info I can't really say much at that aspect. The Surecom meters people have reported funny behavior. One of them is a change in SWR with a change in power level. Theoretically the SWR should not change when the power level changes. The other thing with SWR has to do with the coax cable. A longer cable will absorb more of the reflected power from the antenna end back to the transmitter. With the meter at the transmitter end this makes the SWR look better compared to making the measurement right at the antenna. I've taken advantage of this to get a match under 2:1 on a radio when using an antenna outside of it's specifications and the loss in power, on the coax to the antenna, is the price paid for the benefit. There is no free lunch.

I think most of us on this forum do as well. I try to remind people of the rules without being an A-Hole on the issue. People are adults and will make their own decisions, I just want to help them make an "informed" one. So long as I did what I think is the proper thing to do I let others make their decision whether I agree with it or not.

I remember flying out of the Toronto airport years ago back to the US. Weird part was I went through US customs at the airport before boarding the flight! Arrived at DTW as a domestic flight. I guess that was the point.

My Dad had a CB radio. When he keyed up the neighbor's back yard security light would turn on. ?