Lscott

I have identical radio models where the only difference is the band split. For example my NX-300's come in two band splits, 450-520 and 400-470. The 450-520 has Part 95A while the other doesn't. Both FCC grants are dated for 2013 prior to the rule changes. NX-300 FCC Grant - 2.pdf NX-300 FCC Grant - 1.pdf

Another suggestion is the TK-3170. I carry that one around myself. There is also a TK-3173 which is about the same except it will do trunking. For GMRS you don’t need that otherwise the radio is the same as the TK-3170. The TK-3140 is a good radio as mentioned above. The difference that might make a you pick one over the other is the side port used for programming and options like speaker microphones. The TK-3170 uses the same type of plug that many of the cheaper Chinese radios copied. Also many times you can use the same programming cable too. The TK-3140 uses what Kenwood calls a universal connector. It has 14 spring loaded pins on the plug that makes contact with the pads on the side connector port. The nice thing with this is it keeps dirt and water from getting inside of the radio. That’s the problem with the other radios I mentioned if the port isn’t covered or an accessory plugged in it. There are other commercial grade radios that fit you requirements others here have used and will recommend. TK2140_3140.pdf TK-3173(K) Brochure.pdf TK-2170_3170(K) Brochure.pdf

I'm waiting for delivery on a new NX-1300DUK5 radio with display and standard keypad. This particular model has the ability to be front panel programmed without any hardware modifications or license key loads. One of the option license keys for it enables the 40 bit ARC4 encryption feature. It's a "cheap" license, around $30 more or less. I know it's weak encryption, and has been broken. If a number of radios use it them I might spend the money and upgrade it just to experiment with it. The one nice feature is no key-loader is required, for example AES and DES. My question here what radios currently use this encryption standard? NX-1300DUK5.pdf

Well, there aren't that many non ground plane antennas to choose from. Another point is a non ground plane antenna needs an internal load matching section. That adds bulk and cost to the antenna over a simple 1/4 wave design which needs a ground plane and no load matching section. It's possible that more non ground plane antennas will be marketed as more vehicles employ plastic in the roofs and other body panels to save weight and cost. For those you don't have much in the way of options.

I think some other members here have clarified that for you. Don't be one of those that fail to ID. There are a surprising number of Hams on GMRS. The DF equipment that works on 70cm works just fine on GMRS too. ?

It's split mainly between dielectric losses in the isolating material between the center conductor and skin effect losses in the conductors. The geometry has an indirect effect on both. https://www.resonac.com/solution/tech/transmission-loss.html

For your application I think it would work just fine on transmit. The radio does have a GPS receiver. I don't know if it will pass the GPS satellite signal from the antenna to the radio. There is a filter network internal to the amplifier that would likely block this. In that case your GPS would be non-functional. This would not prevent you from getting APRS packets from another radio however. If the radio has it's own internal GPS antenna then the amplifier won't be an issue. You should be able to get good position data for sending APRS packet info.

That depends on the transmitting radio and the mode in use. The main difference between the two models is the AMP-U25D will work with digital transmitting modes like DMR, P25 Phase 2, TETRA, etc. All of those use a form of TDMA, time division multiple access, which means the radio's transmitter is switching between transmit and receive many times per second and the amplifier has to keep up. The other digital modes don't do this thus the AMP-U25 will work fine. For the small difference in cost I would get the AMP-D25U. At some time in the future you get your Ham license, if not already, and want to try out some of the digital voice modes the amplifier will work. In Ham radio most of the digital voice mode activity seems to be on the UHF 70cm band anyway. One big caveat, the amplifier IS NOT FCC Part 95 certified. AMP-U25D Users-Manual.pdf Internal-Photos AMP-U25D.pdf Review BTech AMP-U25D.pdf Test-Report AMP-U25D.pdf

Nothing like getting a high-resolution photo of the porch pirate giving your camera the thumbs-up as they run off with your Amazon delivery.

Question, if the application is for a nation wide Itinerant frequency does it still have to go through a coordinator? I thought I read it doesn't.

In all fairness I think he wanted to cover all the bases and tried to avoid most of the objections. He does have a sort of dry sense of humor, entertaining to watch. There are some points he makes in the videos that I think are wrong or disagree with, but nobody is perfect.

Who ever came up with that had a major brain F--t. In all fairness it was likely done due to the band getting crowded with all sorts of modes and specific uses. With only 4MHz of bandwidth that can get allocated quick. On UHF the usual 430-450 gives one 20 MHz of bandwidth to use. South of Line-A it's 420-450. For example the vast majority of digital voice operations you'll find on UHF. Most likely due to more room to accommodate it.

I have no doubt you're shocked! The latest version of the radio's CPS no longer allows you to read the radio to get the keys. Of course that does nothing to protect the secrecy of the keys before that point. I have a bunch of Kenwood commercial radios that can use encryption. The encryption, if you can really call it that, is a simple bit scrambler's for the digital part and voice inversion for the analog. The NXDN radios do have a a form of encryption built in, it's part of the "standard" for that mode, a 15 bit scrambler. For a more robust encryption an optional board is installed that can do AES and or DES. there is a port on the back a user can open to install it. That board has to meet a bunch of requirements. See attached file. This more like what you would expect. To load the keys it seems you need a separate keyloader, or a special bit of software to load the keys and a hardware dongle to let the keyloader software to run. This one is for the older version of the module. https://kenwoodcommunications.co.uk/acc/software/firmware/KPG-151AE/ I found your comments about the reliability of encrypted communications interesting. I never gave any thought to the idea it could be any different. Do you have any links to more info on that? Kenwood Secure Cryptographic Module.pdf

Also MURS is limited to 2 watts so why bother? Seems pointless to me. People proposing this should remember GMRS can use up to 50 watts on the repeater channels 15 to 22 and 5 watts for handheld radios on channels 1 through 7.

Yes you must check the FCC emission designators. The confusion stems from how the digital data is modulated. For digital voice mode, DMR, the transmit frequency is shifted by a fixed offset from the channel center frequency. There are typically two frequency steps above and two below for a total of four frequency steps. This is called 4FSK. The details are found in the standard documents for DMR located here for one. https://www.etsi.org/deliver/etsi_ts/102300_102399/10236101/02.02.01_60/ts_10236101v020201p.pdf Scroll down to section 10.2 on page 111 for the frequency offsets used. Other digital voice modes use slightly different methods but the end results are about the same. Here are two more common ones used commercially. NXDN: https://docplayer.net/55804826-Nxdn-nxdn-technical-specifications-part-1-air-interface-sub-part-a-common-air-interface-nxdn-ts-1-a-version-1-3-november-2011.html P25: https://www.qsl.net/kb9mwr/projects/dv/apco25/TIA-102.CAAB-C-2010.pdf Another method to send digital data involves transmitting a series of "audio" tones, most typically two. This is known as AFSK, audio frequency shift keying. If you want to look at the technical details a bit more look at the following link. https://notblackmagic.com/bitsnpieces/afsk/

The Anytone D878 and D578 claim to do AES256 bit. They don't require a keyloader either. https://www.anytone.net/video/products-detail-935076

If you want to operate the radio on Part 90 frequencies, yes. A commercial license can't be obtained to operate on the Part 95E GMRS frequencies. You must have a GMRS specific license. Also if the radio has encryption that also can not be used on GMRS. He was very carefully avoiding the issue of the radio not having Part 95E certification, it does have Part 90. In that case technically you need a commercial license to legally operate the radio on commercial Part 90 frequencies. He made that statement because he knew there would be a flood of comments pointing out the lack of Part 95E certification and the requirement to have a commercial license to legally operate the radio. Apparently he does have some Part 90 frequencies he is licensed to use, thus having the radio, which "just so happens" to have GMRS frequencies programmed into it. With some of the YouTube content creators you must be very careful about what they say. They hedge their comments and some of the info they hand out is misleading at best and just plain wrong at the worst. Unfortunately there are a few that seem to have a large following and have given bad info at times that soon spreads like a virus.

This is a perfect example of why you MUST research the radio(s) you’re planing bidding on, or just buying, on eBay. The key things to look for are the tags on the back of the radio. The next thing to do is track down the manufacturer’s brochures. Those will typically have the exact model numbers and very often the FCC ID’s of those as well. Manufactures makes radios for different markets around the world and lock the programming to versions of the software for those markets only. If you can’t find the software don’t even bother with the radio. You’ll pay good money for a brick. I had purchased two Kenwood TK-3170’s from a seller in Dublin Ireland. They were super cheap at $30US for both. I knew these were the market code “E” radios, based on the tags on the back I saw in the photos and NO FCC ID, whereas for North America it would be a market code “K”. I verified my programing software would work with these before making the purchase. It was the same deal with a Kenwood TK-D300 analog/DMR radio. It is sold in the EU, not in North America. I had the software for that one too so I got it. https://forums.mygmrs.com/gallery/image/255-tk-d300e-fmdmr/?_rid=1908

The link below goes into a bit more detail on the subject. https://www.repeater-builder.com/antenna/double-shielded-coax.html

Or the owner knows somebody who can get them cheap/free access with utilities. They might even work at the business site and have more or less unrestricted acess. A lot of the Ham repeaters get cheap free access by pushing their "emergency response" angle. A few have some affiliation through a government agency like DHS, which the site own gets impressed with al lets them have the space. There are many other angles repeater owners get premium site locations.

I thought I had read something like that before but couldn’t remember where. I guess we’ll see how the works out in practice.

When sales of the existing model falls way down they add a few more features to the radio and release it as the new-and-improved one. Then of course you want it, sell your perfectly good older model at a huge loss. Then you buy the new-and-improved model, which of course costs way more. You're happy for a while until the "new" new-and-improved-model comes out and the cycle repeats.

That's sort of correct. So far the FCC has NOT authorize any type of "digital voice" modes. People are hearing digital voice signals, not necessarily only DMR, on GMRS breaking the rules. Some very brief "data only" transmissions are allowed with significant restrictions. I think sooner or later the FCC will throw in the towel and change the rules. The FCC for years wouldn't allow FM on the CB radio band. Now they changed their mind and its OK.

https://en.wikipedia.org/wiki/Digital_mobile_radio

From a regulation point of view there are only 5 MURS allowed frequencies. A repeater would tie up two of them. Add in more repeaters the open simplex channels would be gone. Then there is the technical issues. For a good repeater system you need to use a split frequency. Currently the Ham 2M VHF band, that's just below MURS, the repeaters use a 600KHz split, which requires some very good cavity filters to achieve it. The only MURS band split that will work is one channel from the 151MHz block and one from the 154MHz block. Then to really screw things up the 151MHz block is restricted to narrow band FM while the 154MHz block is wide band. Also there are NO purpose made MURS specific radios that can even do split frequency operation. That leaves just old Part 90 radios. And it's iffy those can be legally used on MURS, all dependent on on the FCC grant date.