Lscott

Thanks. I missed that. I guess that's what I get for not looking a bit more carefully and just doing a quick scan through the datasheet and dashing off a post. I'm happy to see somebody is interested in the topic enough to look. 8-) So that now brings up the flip side question. Is the bandwidth now too wide? If it's 24KHz then it's way too wide for narrow band FM at 11 KHz. Now it's the reverse of what I wrote in error. Now the normal FM mode is likely OK but not the narrow band mode. Oh well. The FM deviation set for 2.5KHz and the audio gain increased, necessary in narrow band mode using the wide band filter to compensate, will work but the selectivity would suck. Since GMRS is 5KHz deviation narrow band performance likely isn't a big concern. One thing I didn't point out is the power output on the FRS only channels is 0.283 watts as shown in the grant. The FCC allows up to 0.5 watts so this radio won't even do the max allowed output power for those channels. If a potential user is looking at the radio with the idea they may need the narrow band selectivity and the max allowed power on channels 8 to 14, because of a need to communicate with FRS users, may want to consider another radio. In any case looking at the electrical design reveals an aspect of the radio's likely real world performance that isn't mentioned by the manufacture. At least for the GMRS specific version of the radio.

For the more technically inclined people you can investigate a design by looking at either the schematic, in this case it's not available on the FCC website, or the internal photos, which is better than nothing. https://fccid.io/WVTWOUXUN16/Internal-Photos/Int-Photos-4695706.pdf Looking at the PCB photos you will notice a large white rectangular part with "C50F" stamped on it. I've seen these before. They are commonly used ceramic filters. In this case doing a bit of searching you will find a data sheet for it here. http://www.quartz1.com/downloads/Tecdoc/filtr_ceramic/LTWC450F.pdf Take a look at page 4 of the datasheet figure 1. You will see the manufacture's marking looks like the one in the photos. As suspected it's a simple 455KHz IF, intermediate frequency, ceramic filter typically used in a Superheterodyne receiver designs. This would not be something expected in a typical "radio-on-a-chip" design. One thing to note in the spec sheet is the 50dB bandwidth spec of just 12KHz. Considering GMRS has a bandwidth of around 16KHz the filter is a bit narrow. However for narrow band, think FRS, the bandwidth is only 11 KHz it would be a bit too wide. I suspect the designers picked this part as a compromise where they tried to get away with using just one filter in place of the two that should have been used to save money. I think some of the commercial radio designs use two different filters for the two bandwidths. One reason why they tend to work better and cost more. And right next to it is a chip "AA32416" which appears to be the FM detector chip which would make sense. https://www.digchip.com/datasheets/parts/datasheet/849/AA32416-pdf.php Radio internal photos. https://fccid.io/WVTWOUXUN16/Internal-Photos/Int-Photos-4695706.pdf And for those who wonder what a Superheterodyne receiver is there is a nice history and write up here. https://en.wikipedia.org/wiki/Superheterodyne_receiver Looking up the numbers for the other chips, assuming they are not proprietary part numbers for the end user, one might gleam some other interesting details about the radio and it's likely performance.

You might want to try using a different HT. It’s shocking how deaf some HT radio’s receivers are. Particularly the cheap ones.

You can try plugging numbers in to the calculator at the site below. http://www.hamuniverse.com/lineofsightcalculator.html

That could be the case. You can see the FCC data on the radio at this site below: https://fccid.io/WVTWOUXUN16 The FCC certification grant is there. More of interest you can find internal photos of the radio. After looking I didn’t see the typical radio-a-chip device, which seems to be the favorite used in the cheap Chinese radios, on the circuit boards. I didn’t try to look up the chip numbers so the manufacturer could still be using a different one, or a customized version.

If you can find the detailed specifications for the radio look at the receiver section. If the type is stated as “direct conversion” the odds are very high it’s a cheap “radio on a chip” type design.

Interesting point about who owns the system and has the right to shut it down. One has to wonder where else kill switches are installed and who has their finger on the button.

I think that was the time where the government shut down cell phone service for several hours?

I think that was the time where the government shut down cell phone service for several hours?

For quickly planed events, or just a spontaneous group gathering, it's likely true. I agree with the comment for the more organized groups. The frequencies used I doubt would change that much, would have to reprogram a lot of radios which isn't practical when people need to be deployed quickly. What would be hard is figuring out their "com sec" protocols. That can be quickly changed by just handing out the radios with a sheet listing the special codes used at the last minute. With that said there are likely elements who are technically competent, various radio hobby orientated individuals, who could show up with the appropriate equipment and have no affiliation to any organized group. As pointed out the UV-5R is readily available and still very cheap. It wouldn't be a budget buster for somebody to keep a handful of these at the ready, per-programmed, show up at the event and pass them out to selected people. The positive point is those radios don't use any form of voice encryption or scrambling. So using a scanning type radio, likely easier done with an SDR dongle which can watch a wide chunk of spectrum, so when strong pips shows up zero in and see what can be heard. Might get lucky.

People are cheap. I guess if you wanted a radio for a specific use and have no interest in radio as a hobby you would buy the cheapest thing that does the job. The strange thing is these radios are cheaper than the bubble pack FRS radios, in a dollar per radio sense, in most cases.

Looks like a nice radio. What I like about it is the receiver is a true superheterodyne design. I haven't been impressed with the performance of the cheaper "radio on a chip" types that all seem to use the ubiquitous RDA1846S, or some variant of it. You get what you pay for. The D878-UV analog/DMR radio, which isn't cheap, I think uses the chip but seems to perform better than I would expect. I think the design uses a tracking filter on the receiver front end to help eliminate the nasty image responses you get with the radio on a chip design.

I got "back" into GMRS when the FCC changed the fee to something more reasonable and the extended the license term to 10 years. I was licensed before and let it expire, 5 year license term and around $100 was a bit much. Now if I ever need to keep in contact with a family member all I have to do is hand them a programed radio and some simple instructions. I also have some friends who so far have not been licensed for Ham radio, due to COVID-19 no test sessions or too busy to study for the Ham test, but filling out a form and paying the $70 was a easy. GMRS is the only way I can talk to them by radio currently.

The first point is one of the reasons why the FCC started clamping down on the cheap Chinese radios. I had a buddy that was fooling around like that with one. I got him to test for and received his Ham Tech Class license. He's having a lot of fun now, getting into the digital voice modes and hot spots. I'm only aware of a few radios older radios that have any kind of scrambler function. Many of the older FRS radios used simple voice inversion. I believe the FCC put an end to that with the rule revisions in 2017 which became effective in 2018. I know of several current higher end Chinese radios that will do digital encryption since they are both analog and digital (DMR). Several of the older Kenwood LMR analog radios have either built in simple voice inversion or the user can install a more advanced voice encryption module. I have a few of those old radios, used off of eBay of course without that option. You wouldn't believe what those boards cost. I checked in case I ever ended up with a used radio that had one installed. You never know. https://www.ameradio.com/product/512172/description.html (Just one of the several types they sell) The PDF files have some interesting info on the modules. On your last point that does bring up another question. Has anybody seen what kind of radios are being used? Apparently the link in my first post seems to show the cheap UV-5R is widely used. The article is an old one so I would guess some other make and model has taken its place.

The point is well taken. The info is just for general information and monitoring. After seeing photos of people carrying around what is obviously two-way radios I got curious if anybody happened to pick up the communications. There were a few protests by me and all I heard were comments by the mall security guards since some of the protesters had used it for parking.

I’ve noted more protesters are carrying two-way radios. Anybody have an idea what frequencies seem to be the favorite ones used? The Baofeng UV-5R looks looks it’s the go to radio recommend by many prepper and militia groups. Poor choice IMO. https://radiofreeq.wordpress.com/2016/01/19/militia-radio-frequencies/ I’m guessing most of the radios are the cheap Chinese ones since you program them for operation outside of the Hams bands with requiring modifications. They can be easily programmed for the public service frequencies which likely accounts for the reports of police radio communications being jammed in some cases.

Humm... That makes all the difference. Given the costs you mention it does explain why businesses are jumping on the free radio services. I knew there were some costs but had no idea it was that expensive. Given the numbers above isn’t the likely outcome FRS and MURS will become primarily an unlicensed business radio service?

I should have been more specific. FCC will not issue a new GMRS license to a business. If the owner and his employees have their own that’s OK as you correctly pointed out. Then each person can use the service under their individual license of course. What I was trying to get across if enough businesses end up using MURS that would likely crowd out those who want to use it for personal use. There are only 5 channels after all. If a business really needs radio communications I think there are better choices, such as getting licensed and one or more frequencies assigned for their use by the FCC. Around me there are a significant number of businesses using FRS radios, which seems to be on the increase. Mostly the old 1/2 watts models. Fortunately those don’t travel that far. The newer radios at 2 watts are more of a problem. Given that MURS allows up to 2 watts it won’t take many frequent users to occupy those 5 channels, and for some distance as well. Which gets me back to the topic of just how popular is MURS? From some of the posts, and my monitoring in my area, it hasn’t caught on with that many users yet.

Exactly my point!

Oops pasted in the wrong link for the Kenwood brochure with the radio info. This should be the right one. http://www.lauttamus.com/_pdf/TwoWayRadio/Kenwood/tk-270g-370g.pdf

In the way of hand held radios I've used the TK-370-K, TK-370G-1 and the TK-3160. Generally the 450 MHz to 470 MHz frequency split versions can go outside of the official range by 10 MHz or so. My favorite is the TK-370G-1 model. By the way it's also Part 95 certified so there is no question it's legal to use on GMRS. It's found on Ebay for a reasonable price if you look carefully. Batteries and antennas are readily available if the one you want doesn't have it. It can use the cheap Baofeng type speaker mics, head sets, antennas (yes they use the reverse SMA type on these radios just like the Chinese) and programming cable. https://forums.mygmrs.com/topic/2022-kenwood-lmr-for-ham/ I've also had good luck with the TK-270G-1 VHF version for 2 meters. Both radios are bigger than most of the newer compact radios, heavier but built like a tank. If you get one be sure you get a charger with it if not look for the KSC-16. I've had good luck finding the programming software for it, KPG-56D. Forget using Chirp. I've never had a version of it that didn't mess up trying to enter frequencies in to it for the "G" versions. For the simple TK-370-K it seems to work OK.

IMO business use should be prohibited. That's done for GMRS currently. There should be plenty of UHF business exclusive frequencies available for licensed use. With only 5 MURS channels it won't take much business traffic to make them unattractive for private individual voice communications. If businesses say that UHF is too congested for licensed UHF frequency and that's why they use MURS on VHF perhaps the crap below is one reason. I just can't understand why a business like a shopping mall needs to run a 35 watt repeater. It's only used by the mall security detail. https://wireless2.fcc.gov/UlsApp/UlsSearch/licenseFreqSum.jsp?licKey=3354643 I'm about 5 miles away per Google Maps and I pick them up clear as a bell using a simple HT on a table top in my house. Does everybody in a 5 plus mile radius really needs to hear them chasing shoplifters out the door and through the parking lot?

It seems to be a shame MURS doesn’t get more use by private individuals. You get to run 2 watts, like FRS which also doesn’t require a license, and external antennas which are not allowed on FRS. In fact any legal FRS certified radio the antennas can’t be removed. I’ve run across dual band mobile antennas specifically tuned for MURS and GMRS. Used with a cheap duplexer one can operate a MURS radio and a GMRS radio, if you’re licensed. The radios can be operated one at a time or at the same time with the duplexer providing the isolation between the radios. The duplexers are cheap costing as little as $30 not counting adapters and patch cables.

I'll guess the usual suspects are about as light and cheap you'll find, GMRS-VI and the TR-505G. https://powerwerx.com/tera-tr505-gmrs-recreational-handheld-radio The BTECH you already have. I would suggest you just get anther one, they're fairly cheap. That way all the accessories are interchangeable, external speaker microphones, antennas, battery packs, mobile battery eliminators, programming cable etc. Then you only have to deal with one programming cable and software. You can make one code plug, radio memory file, and use it on both radios unchanged. Trying to keep two different radio's code plugs compatible is a bit of a pain. Been there done that many times. Finally you only need to learn one radio, not two, and the various menu items and settings. You also don't have to worry about which radio you grabbed and trying to remember how to use it later if that's not the usual one you carry around. On the last point I typically keep all my radio manuals in PDF format and loaded on the smart phone. If I need to use a feature I can't remember to access or setup the manual is right there.

Other than a few local businesses, seldom heard, I almost never hear the frequencies used for voice communications by private individuals. There are a number of old Part 90 radios that predate the creation of MURS so they could be used, grandfathered in, and a number of new radios that are reasonably priced and Part 95 certified for it. So the question is just how many people really use it other than businesses or for a wireless intercom/data applications?