Lscott
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Posts posted by Lscott
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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.
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2 hours ago, wayoverthere said:
I wonder if it was a "not approved" or if Kenwood just didn't submit the 400-470 models for dual certification? Was that rule in what they'd certify earlier than I realized, before the record?
I checked the grant on my vx4207, and it shows 2004, with 22, 74, 90, and 95a approvals
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.
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12 hours ago, Guest Random name said:
I don't know why it is so difficult for HAMs to realize that GMRS has a different purpose from their stuffy radio hobby. It's like they just can't stand that they don't own the market on playing radio anymore and so they want to impose their stuffy crap on a system that is specifically for a different purpose. If you're a HAM and your rules and way of playing radio is so much better then GO USE HAM FREQUENCIES and leave us Neanderthals to our 22 channels! Oh but you can't, can you? Because all those frequencies are dead air and y'all can't stand to see a good party across the street without showing up and bringing in your rules. You want to come to the party then you play by our rules, you don't like our rules go have your own party in your own bigger house with more rooms.
You're going to find a lot of Hams on this forum too. There is nowhere for you to hide.
- wayoverthere, WRQC527 and Sshannon
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2 hours ago, wayoverthere said:
If you're meaning the Kenwood's and Motorola's with dual 90/95 certification, that became verboten in the 2017 rules rewrite that also moved gmrs from 95a to 95e, iirc.
Prior to that, when it was in 95a, the overlap was allowed (I have a 90/95a vertex mobile that covers 400-470mhz, for example)
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.
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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
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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?
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18 hours ago, WRUU653 said:
I was wondering why more people don’t go with an antenna that doesn’t need a ground plane when one isn’t easily available.? Would it be safe to say all things being equal that an antenna with a ground plane is best? Also is there any benefit to a non ground plane type antenna in an application that does have a ground plane?
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.
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16 hours ago, Adamdaj said:
I know that I have read the current FCC part 95 E rules and regulations and tried to comprehend them. However, I may have misinterpreted the rules for repeaters.
I think some other members here have clarified that for you.
16 hours ago, Adamdaj said:I have monitored the LEARN 462.575 repeater and I have noticed that only a few members ID as required by the FCC. However, the majority of LEARN membership just use their unit number, such as unit 822. If Amateur Radio Operators did this, the OOs would have a field day sending reports to the FCC and possibly Fox Hunting.
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.
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On 2/24/2023 at 11:52 AM, Blaise said:
What is actually going on internally that makes one cable less lossy than another? Is is just thickness of conductors? Geometry tricks? Shielding?
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
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6 hours ago, Guest nodoze said:
Thanks Lscott!
Do you think that the regular non-digital AMP-U25 will allow an amplified GMRS-PRO communicate GPS/messages/etc with other GMRS-PROs?
It sounds like you think the AMP-25D should work fine.
I wasn't sure from your response if you were thinking both the AMP-U25 & AMP-U25D should work for the regular interoperability/usage of multiple GMRS-PROs.
Unfortunately I can't yet access the PDFs you posted... I submitted my request & paid for my GMRS license but am waiting for FCC to process so only have guest access for now...
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.
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14 hours ago, Guest nodoze said:
Does using APRS mean you need the AMP-U25D (digital version)?
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
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1 hour ago, WRKC935 said:
When you are sitting in meetings and your phone beeps when Amazon drops a package on your door step with a photo from your video system it happened, they figured I would be the guy to learn the product. I just haven't convinced them to let me borrow the facial rec camera's yet.
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.
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On 2/26/2023 at 8:22 AM, gortex2 said:
To get a commercial license or LMR license you need a reason. A home repair shop is a valid excuse and will allow you to apply for a frequency. In the LMR world a license is mostly for 1 frequency. Not a huge block like GMRS or Ham. In public safety world you can apply for multiple as well as in business LMR. Location will dictate what frequencies are available in your area and what sections of frequencies you can apply for. All Part 90 frequencies require coordination so even if you fill out the 601 your self it needs to go to a frequency coordinator for approval prior to the FCC. There are various frequency coordinators for public safety, business, etc. Each one will require a fee on top of your FCC fee. When I did alot of these for work we would quote $500 for 1 frequency. Many came in around that but the last channel I did was $250 per frequency (460/465 mhz) so it was $500 just in coordination plus FCC fees as well as our fees for our work.
Public Safety still pays coordination fees, but is exempt mostly from the FCC fee. The other major issue is location. Some locations have no frequencies available and frequency reuse happens. Also above Line A requires all FCC licenses to go to Canada. Our last SAR frequency was in Canada for almost 2 years until we got approval.
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.
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8 hours ago, Wrvq441 said:
I am aware that it is not legal to use encryption on GMRS. I’m just curious about the different licensing out there. I never felt misled by the video.
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.
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5 hours ago, marcspaz said:
Unfortunately, on the VHF amateur bands, channel spacing is 15KHz across most of the country.
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.
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46 minutes ago, WRKC935 said:
That right there is frankly terrifying. There are standards and requirements for encryption to keep it secure. At least for P25 equipment. One of which is the fact you can't see the key other than when it's typed into a key loader. Once it's in there, it can't be read by others. And it's never fully displayed on the key loader beyond that. From what you are showing me here, someone could take one of these radios and read it and have the key. In any compliant radio, if you open the radio and attempt to access the UCM (crypto module) the module dumps the keys in it. The backup battery for the memory actually gets grounded through the cover that protects the module. Removing the cover disconnected the battery from the module and the memory gets erased. Again, this is a P25 standard, DMR standards are not gonna be that high.
There are a number of other standards and requirements for securing the keys in a compliant encrypted radio. It seems that this radio doesn't meet any of those requirements. But I am thinking these radios are DMR and not P25. I have not messed with AES on DMR. The MOTOTRBO radios in the US I don't believe are available with AES encryption. I know there are some that have it, but the ones I know of had it hacked into the radio . It is available in other countries however.
All that being said. I would question if the Anytone radio does any sort of analog encryption AES or otherwise or if it's JUST for DMR specifically. Both DMR and P25 are both digital formats that a data stream gets transmitted and not analog audio. Both have added parity and other information in the data stream beyond the audio intelligence.
But I also remember that DVP and DES OFB in analog would significantly decrease range because there was no error correction on it at all due to there not being any overhead data stream being transmitted for error correction to take place. And those were significantly less secure and complex than AES referring to the complexity of the key and the algorithm. It did require a full quieting signal and any interference on the frequency in use would stop the ability of the receiving radio to decrypt the signal.
But being able to read out a radio and see the encryption key in that radio almost completely defeats the purpose of having encryption to begin with.
I guess I should preface this with the fact I keep my encryption info and key loader in a vault located in my gun safe. So it's stored in a vault within a vault. The paper documents that have my keys written down on them are in the same place. While I do have keys that are shared outside my equipment with others, I load those radios and key loaders for those that have them and I don't share MY personal key with anyone. All my gear is multikey and the stuff I have in my inventory get keyed with a number of keys including my personal key that only exists in my radios. Do I have a specific reason to take it that far? Not really, other than personal OPSEC. But I can do it that way and the 'family key' isn't loaded on any gear that someone outside the family would have access to. But when I switch to channels that are strapped secure and say something on those channels, I have little doubt that no one else hears what is said.
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?
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1 hour ago, jwilkers said:
No. GMRS and MURS are 2 different radio services.
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.
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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:
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/
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57 minutes ago, WRKC935 said:
First is radios that support that encryption algorithm. Then you will need a way to put keys in the radios (a keyloader or some hardware tool that will load keys)
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
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9 minutes ago, Wrvq441 said:
In the video Randy stated that in order to please the frequency gods, one must have a FCC Commercial License to operate this radio.
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.
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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
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2 hours ago, kmcdonaugh said:
So I have had some people swear up and down that LMR-400 should not be used on a repeater. That after some time the sensitivity will degrade and it "will cause noise". Now for what I use mine for, it is probably good enough. But I have researched a little bit, and found that yes, for repeaters that experience heavy use this could eventually become an issue. However, it seems that is the case for regular LMR-400. I have found that this noise is actually from wire braid coax, and that you can actually buy LMR-400 that isolates the the two shields so the wire braid is not touching the foil, and does not cause the noise. My question is, is this a serious enough problem for the average repeater owner to even care? My opinion is no.
The link below goes into a bit more detail on the subject.
https://www.repeater-builder.com/antenna/double-shielded-coax.html
- kmcdonaugh and Sshannon
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44 minutes ago, kmcdonaugh said:
Most of the GMRS repeaters that do have really good range, usually belong to some sort of club
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.
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6 hours ago, tweiss3 said:
Re-reading the rules for something else, thought of this thread:
47 CFR 95.1733(a)(9) Prohibited GMRS Uses: Messages (except emergency messages) to any station in the Amateur Radio Service, to any unauthorized station, or to any foreign station;
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.
Looking for business style gmrs 5w ht
in Technical Discussion
Posted
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.