Lscott

I don’t know what kind of range you’re expecting out of the radios. The two with antennas close to a full quarter wave, around 6 inches, would have been on my list. The other two with munchkin sized antennas I doubt will perform as well range wise to the other two. That’s assuming they are all equal, in power output, another area where manufacturers don’t generally put that in the specifications.

That looks like the one. The link for the simulated HT case for testing is at this link. https://reflector.sota.org.uk/t/antenna-testing-jig-swr/14791 Looking closer you can see the "long" length of center conductor and shield braid going to each socket. This should have been kept as short as possible. Ideally he could have used one coax cable pigtail for each of the two sockets. There is a comment that the measured SWR's are "High" by 0.7 when verified against a dummy load, likely due to the above issue with the coax cable pigtail wiring. Anyway testing HT antennas isn't going to be so straight forward or easy.

That might be hard to measure, with or without the tigger tail. You would just about need to strip out the guts of the radio and run a pigtail out of it to the SWR meter. I haven’t seen how the manufacturers test their HT antennas but I would guess they do something similar. I ran across a web site where someone built a simulated HT case with antenna connections on the top using a hollow block of aluminum. The test setup wasn’t that good since there was a noticeable length of open wire connecting the sockets together. At UHF that can really screw up the measurements. This topic has come up before on the forum. If you can find some of my old posts some of them have links to web sites where people have attempted to measure HT antennas. If someone wants to give it a try I’m sure others would be interested in the results.

I’ve measured a number of my HT antennas. Originally I thought using a good ground plane would improve the match. Most didn’t, in fact some got worse. Since the human body ends up being part of the antenna system trying to qualify it for measurement purposes is difficult. In one test I did the best match was when the base of the small magnet mounted antenna was resting on the back of my hand held out at arm length. I was using a special small base magnet mount with an SMA connector on it for the tests. For a ground plane I used some sheet metal for heating duct work about 36 inches on a side to simulate a vehicle mount condition. All testing was done using a Rig Expert AA-1000 antenna analyzer. https://rigexpert.net/index.php?route=product/product&product_id=57 Remember for GMRS a quarter wave antenna is about 6 inches long. An efficient antenna to match well is a half wave length long, in the case of GMRS that’s about 12 inches more or less. The metal case of the radio supplies the bulk of the missing half of the antenna, AKA ground plane. Adding a tigger tail likely won’t make much difference unless you have a tiny sized radio. Now if it was VHF there is some benefit seen when used.

You can try removing the antenna from the radio and see if the noise is still present. This will reduce the sensitivity of the radio a lot so the noise source will have to be very close to it. If not then hold the radio up close to the dashboard while moving it around and see if it picks up the noise. You can also try it around the exterior of the truck too. If you pick it up chances are the source is very close to the radio.

By any chance were you using the repeater function? I'm not familiar with the exact radio but I believe you can select between what is call simplex operation and using a repeater. Using the repeater function, which should only work on channels 15 through 22, the radio will try to transmit on the 467.xxx frequencies which is noticeably higher than the frequencies on the channels below that, 1 to 7. That might account for the higher SWR reading on those higher numbered channels. The antenna might be optimized for the simplex only 462.xxxx frequencies. In any case you need to get the antenna up and in the clear to get some decent range out of it. That is critically important at the frequencies used by GMRS.

That should come in handy. Thanks.

Do you have a booth number? There are maps showing the booth layouts and are numbered.

It usually is there. With a turnout over the event weekend of 25K plus it gets sort of crazy. It typically takes me the full first day just to walk through the flea market area. Second day the indoor vendors. Then on the last half day looking around to see who is still in the flea market area and wants to make deals so they don't have to pack the stuff up and take back with them.

Don’t miss place your checkbook.

You can frame it anyway you like. You’re still rolling the dice that nothing is going to happen. You might get away with it, until you don’t. And yes the FCC issues $10k fines. They have done it before, in the following case for simple unlicensed operation on GMRS. https://transition.fcc.gov/eb/Orders/2011/DA-11-157A1.html Note that nothing else was mentioned as the cause for the fine, no interference etc., just unlicensed operation. They were even using purpose built GMRS radios, from Midland no less, not even modified Ham gear as you suggest. Further on the FCC said that simple ignorance of the necessity of getting a license does warrant any reduction in the fine. They aren’t screwing around. You should also read this too. The FCC might have mercy on the unlucky, but then again maybe not. The government is running a big deficit, I guessing they won’t be in a charitable mood. Small staff in the enforcement section, they need to set some examples. https://www.law.cornell.edu/cfr/text/47/95.313

Show me a PDF scanned correspondence on FCC letter head stating they won’t.

Yeah, same crappy logic the 11M crowd used to explain away their actions running excessive power and running out of band. A few them don’t think it’s so funny or an academic issue when the FCC was finished with them. When they get annoyed enough they will make an example out someone. You’re betting it won’t be you. If you want to play the game of twisting the dragons tail don’t start crying when it gets annoyed enough to turn around and flame you.

Check the FCC enforcement logs to see what kind of fines they issue. And if you still don’t believe it then all you have to do is ask them.

That gain figure I’ll bet is 2.15dbi, or the gain over an isotopic antenna, which is a theoretical antenna that physically doesn’t exist. A simple dipole or 1/4 wave magnet mount has the same gain, 2.15dbi. Manufacturers like to quote gain figures in dbi, verses dbd - gain over a dipole, because it inflates the numbers making the specifications look more impressive. External antennas can, and many do, have high gains over a simple dipole or 1/4 wave type. There are a number to choose from. One thing seems to be true, the higher the gain the bigger (longer) it gets. I have a dual band high gain antenna on my Jeep. It’s nearly 5 feet tall as an example.

As others pointed out it depends on what is between the two radios AND how high the antennas are. Assuming no obstructions you can estimate the range by taking the square root of the antenna height above ground in feet and multiply it by 1.4 for the range in miles. For example a repeater antenna at 150 feet would be about sqrt(150)*1.4 = 17.1 miles. Then you do the same for the mobile radio. Lets say it's a hand held at 5 feet. So we get sqrt(5)*1.4 = 3.1 miles. The total would be 17.1+3.1 = 20.2 miles. There are a lot of other factors that could extend that range a bit, and most likely reduce it.

I periodically look for various radios on the Internet. Recently I've been looking at some for dPMR and stumbled across some manufactures I'm not familiar with. It's not really used in North America, yet, but might be cool to play with on the Ham Bands. These companies make analog/dPMR/dPMR446/DMR446 radios. Yeah, it's sort of confusing, in Europe they have Two digital modes for their license free service, dPMR446 and DMR446. One is the FDMA dPMR and the other is TDMA based, the usual DMR mode. If that isn't confusing enough the dPMR standard allows the use of two different vocoders with the option to use a third one that is manufacture specific. There are three class of equipment depending on the vocoder. https://dpmrassociation.org/downloads/2019-docs/Certified-Interoperability-Guidance-Paper-2019.pdf https://dpmrassociation.org/downloads/2019-docs/dPMR-MoU-tech-lib-Voc-Bits-V1-2019.pdf For analog and DMR/DMR446 I stumbled this company and their radios. I've never heard of them before. They sell analog/DMR radios. https://dts.solutions/wp-content/uploads/2020/11/Entel-DTEx-Land-Series-Brochure-from-DTS-Solutions-UK-Ltd.pdf https://www.dmrassociation.org/entel/Entel-DX400-SERIES.pdf Anybody used their equipment or have any experience with them? At least they give away for free the programming software unlike the recent moves by Kenwood to look more like the Motorola where they nickel and dime you to death for every tiny option and license entitlement key hell.

Business may not give a crap about it since they usually go through a dealer for programming and support. They don’t have to deal with the hassle. Now the dealers on the other hand may not like it much. When the dealers start bad mouthing the products the manufacturer is screwed. However if the end user thinks the radios will have a residual value on the used market when they want to upgrade, are they going to be surprised.? I’m seeing some on eBay now. I have ZERO interest in owning one. Just give me one of the older models, install the software, I can program all the radios I want.

The radios look nice, but I really hate the licensing model they use, it SUCKS. Maybe for business it might make sense but for private use, IMHO, no. I have a large collection of radios. All I need to do is start the CPS for the specific model series and program the radio. I don't have to screw around and worry if the particular radio is licensed. If I get another one, just plug it and program it, no hassle, done. It's also the same sort of thing with Motorola. I think Kenwood just copied their business model for their new radio series.

I thought that P25 was popular in California? I know NXDN has a big following on the west side of Florida. They have a linked repeater system there. https://ni4ce.org/nxdn-digital-communications/ Here in Michigan it's D-Star, DMR and YSF. The are a few P25 repeaters around https://www.repeaterbook.com/repeaters/feature_search.php?state_id=26&type=P25 and one NXDN enabled repeater. https://www.repeaterbook.com/repeaters/details.php?state_id=26&ID=390 Popularity of NXDN might be picking up in some areas. It's also used by the railroads. I'm also surprised by how many schools use it. I guess it's cheaper that P25. As a side note I monitor the local shopping mall and FRS/GMRS frequencies while I'm at work in the office. I use one of those triband CCR's for that. Anyway again I was picking up intermittently somebody running DMR on channel 18, that very characteristic pulsing noise on FM. The signal isn't strong, with the building being a bit of a Faraday cage, it's not close by. I guess we're likely to be seeing more of this as people end up buying the cheap analog/DMR radios and program them up for FRS/GMRS. A good site for looking for digital frequencies is here if it's registered with the FCC: https://digitalfrequencysearch.com/index.php

Yeah, that would be interesting. Since the GMRS rules were changed back in 2017, were businesses can no longer apply for new GMRS licenses, there is no reason for the usual manufactures to apply for any Part 95 certifications for their expensive commercial line of radios. Businesses won't be buying GMRS commercial grade radios. That just leaves the cheap consumer grade stuff, most originating from the Chinese companies. Yup, he's the one I was think about.

I'm inclined to agree with you on that point. I also have two other examples. I looked at my TK-5320's. Its the same thing. The FCC ID's are exactly the same. I guess the guts are are similar enough to not require a different ID, but the firmware is different. The NX-300's do NXDN while the TK-5320's do P25. Unless you pop off the battery pack and look at the model numbers on the back of the radio's case you can't tell them apart. https://comms.kenwood.com/common/pdf/download/TK-5220_5320_Specsheet.pdf I think I ran across a post somewhere that claimed one could convert the hardware from one digital protocol to the other. I can't find it now. One of the other posters here worked for JVCKenwood and had some info on the topic.

That seems to be the case. I have several UHF radios in my collection. Some are certified Part 95A, the old rules, NX-300's. Those have a stated official frequency range of 450 to 520 with the FCC ID ALH378500. Those are Part 95A. The exact same model with a stated official frequency range of 406.1 to 470, FCC ID ALH378501 are NOT Part 95A certified. The frequency ranges above are what appears on the FCC grants. Note both cover the GMRS frequencies. The difference is the second one also covers the US Ham 70cm band too. I can't say if the lack of Part 95A certification is due to the manufacture not applying for it or if the FCC wouldn't give the certification. https://comms.kenwood.com/common/pdf/download/02_NX-200G&300GBrochure.pdf Also note the radio can do digital voice mode even with the Part 95A certification. Of course that in noway implies using digital voice on GMRS is currently legal.