Lscott

After being disappointed by one, or more, you learn why people spend a lot more money on better radios soon after. I have a buddy at work that purchased several Baofengs for GMRS. I got him to spend money on a good clean Kenwood TK-3170 commercial radio. https://forums.mygmrs.com/gallery/image/263-tk-3170jpg/ Since he started using the Kenwood he doesn't bother with the Baofengs, and comments how the Kenwood works better. With these cheap Chinese radios, CCR's, you get what you pay for, and maybe not even that is some cases. ?

Isn't that what the radio is used for? ?

I see there are some repeaters on P25. You going to do any for NXDN?

I was reading the post as activating a new repeater. I was wondering if another one besides the Detroit and Mt. Clemens machines was going in some place. I was talking about the above repeaters at our Thursday night coffee group meeting. One of the Hams mentioned your name I believe. He has the cross-band repeater in Melvindale. Another Ham in our group just put up a repeater on UHF a short while ago. I was suggesting he could get his GMRS license and put it on the band. That would provide coverage out on the west-north-west side of the Detroit area. I believe he has access to emergency power at the site.

One of the new GMRS repeaters by me does so using a female voice. It even announces it’s an open repeater and the access tone required.

Where do you plan to locate the repeaters in the area?

Oh, if you're worried about getting the channel selector set to the wrong position on any of the radios. Just program all the channels exactly the same. Then it doesn't matter where the channel selector is set.

A similar radio to the VX-231 from Kenwood are the TK-3160 and TK-3360 16 channel radios. Neither one is Part 95 certified however. The TK-3360 is a somewhat newer version of the TK-3160. Both are basically idiot proof. There are only a channel selector, volume control, transmit button and two optional programmable side buttons. You could give one of these to a 5 year old and not worry much if they will much something up. TK-2360-3360 Brochure.pdf TK-2160_3160 Brochure.pdf

Good question. I never got into the details of what the technical qualification are pertaining to frequency range to get certification under the various FCC rule parts. It could just be Kenwood felt the 450-520 band split was a better fit to cover the commercial market. Before the rule changes businesses could get a GMRS license. The 400-470 band split doesn't cover the upper end of the commercial market. It's likely a better fit for markets outside of North America.

You're going to find a lot of Hams on this forum too. There is nowhere for you to hide.?

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/