Lscott

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.

Probably none. The cost to install those chips, parts - labor - shipping, would very likely exceed the cost of a new radio with them. Unless you have the expertise and equipment to install them yourself I would just buy a new radio with everything installed and working.

That’s what HT’s do.?

There is a nominal 11 year sunspot cycle, minimum to maximum number of sunspots. Near the peak, maximum number of sunspots, there is a lot of long distance propagation on the HF bands, which includes the 11M CB band. It wouldn't be unusual to pick up stations 100's to maybe 1000's of miles distance. That would increase the back ground noise level you noticed. The sunspot cycle has very little impact on VHF, and particularly on UHF. At VHF and UHF there are other ways signals can propagate long distances. It has mostly to do with the weather. https://3fs.net.au/tropospheric-ducting/

That's why we get some of the people we see here asking for help. Crap documentation from the manufacture and confusing menu selections in the radios.

Writing up technical material isn't easy to do, time consuming and trying to make it understandable takes a good bit of effort. I've done it at my work place a few times. I can appreciate what goes into it.

That's something you have to determine for yourself. I had a similar situation with "radioreference.com". I asked for some opinions here about paying the membership fee. After some helpful comments I decided it might be worth it so I paid for a two year membership. There were some features and data I wanted to use, and could have found elsewhere with a lot more effort, so I'm giving it a try since it did save me time and trouble.

marcspaz You did a great write up on this. It should be required reading.

So long as those stations are operating under the same license as the owner of the repeater. If not then the repeater must self identify. For a private repeater placed into service for use by a family that's the case above. The problems start when "Open Repeaters" are put into operation. The logic for the above is easy to figure out. Any station using the repeater, and operating under the owner's license, when they identify it would be the same ID used if the repeater self identified. So requiring the repeater to self identify using the same call sign would be redundant. When a station identifying itself under it's own license is not identifying the repeater with the owners ID. Thus the repeater needs to self identify. This is has all been covered and debated multiple times here. Too many people get hung up on the difference and don't understand the key point and simply spread the wrong advice around further confusing even more users. It doesn't help when the FCC has neglected it's duty to enforce the rules where people mistakenly assume the lack of enforcement as proof they're right, no they are still wrong.

It's done all the time. You will need a calculator with a square root function. Look under the heading in the below link: "VSWR formula using forward & reflected powers" https://www.electronics-notes.com/articles/antennas-propagation/vswr-return-loss/vswr-calculations-formulas-equations.php

And that is of the full scale reading too! So if the full scale is 20 watts your reading could be in error by up to 2 watts. Trying to measure the output of a 4/5 Watt HT and getting a 2 watt error you don't know if it's the wattmeter or the HT that has the problem. I think with the Birds you can get a 5 watt slug so when checking low power, like on HT's, and a 5% error rating, you get a pretty accurate reading. I'm also looking at getting a good Bird wattmeter in good condition with "N" connectors on it. So far everything I've seen used is like $300, for a beat up one, to $400+ for a used one in good condition. Then there is the cost of the slugs, which you end up with a collection of those too, and they aren't that cheap either. I have a buddy who is a full time radio tech at a local city transportation department. He uses a Telwave. I've never heard him complaint about it, and he uses the crap out of it, field and bench work. I have a Diawa meter currently and I'm not that impressed with it. https://www.dxengineering.com/parts/dwa-cn-103m

Some people seem to have a hard time grasping the idea of a frequency offset between TX and RX and can't get into their local repeater either.

It gets a bit more confusing when you include gain antennas in the mix. For example with a simple 1/4 wave antenna lets say your S-meter reads 2 S-units. Then switch over to an antenna with 6db of gain now your S-meter will read 3 S-units. Nothing on the TX end or path changed other than your antenna.

Ah, a proper FM demodulation circuit includes a limiter stage designed to deliberately remove any amplitude changes, before the discriminator stage, so it response only to the frequency deviation. For good discriminator performance there has to be sufficient signal amplitude to achieve full limiter action. https://www.arrl.org/files/file/Technology/tis/info/pdf/8506025.pdf

Anyway back on topic here. I did an analysis of an antenna system I want to install on my new ride. I had a choice between several different cable types and lengths along with antenna and mount. I wanted a roof rack type mount so the antenna had to be a 1/2 wave type that doesn't require a ground plane. The goal was to see which combination was the best case compared to what I can get to fit. I have to route the cable around a tail light assembly and it has to be behind the rear hatch. It's a very tight fit for the cable and I'm not into drilling any holes. I went a bit overboard with the analysis but gives you an idea what things to consider. For example some of the cable loses can be made up, sort of, with a higher gain antenna. That's one of the trade offs you can make. It looks like what will work is the short coax cable mount, using RG-316 thin coax cable, with an RG-8 mini cable extension. Keeping the mount with the RG-316 coax cable length short makes a difference. The mount using RG-58C is a bit better but the difference wasn't more than a few percent different from the one I think will fit best. If range was ONLY a function of power then the range change varies as the square-root of the ratio of the powers. I calculated a likely range change based on the square-root of the ratios of power loss/gain between the different configurations. One point about the cable connectors. They are all RG-8 mini type, including the one on the end of the coax cable used on the mount. It comes with a RG-8 mini to PL-259 adapter. The RG-8 mini adapter is a constant impedance type, the normal PL-259/SO-239 are not, thus there is likely to be little in the way of SWR issues using RG-8 mini through out the system. The adapters are rated up to 2.5GHz and the insertion loses are very low. Diamond C101 Cable Assembly.pdf Diamond C110 Extension Cable.pdf Diamond K550 Luggage Rack Mount.pdf Mazda 2023 CX-5 Antenna System Analysis Rev 5.pdf SG7500A.pdf Coaxial Cable Attenuation Chart.pdf