Lscott

Yeah, having NOAA is useful if you spend a lot of time out doors. However that requires the radio to likely be based on a dual band design, a derivative of a VHF/UHF Ham type radio with GMRS specific firmware. Some of the GMRS radios are based on a single band design so that's why they don't have VHF and thus no NOAA station reception. I would just go for a good quality GMRS radio and then spend a bit extra and get a cheap Baofeng UV-5R type radio for about $25 or so and program in the NOAA weather channels in it. You're not really going to be transmitting on it, just using it as a monitor. I typically carry a TK-3170 for GMRS and UHF ham. For VHF Ham and NOAA I have the VHF version of the radio, TK-2170. https://pdfs.kenwoodproducts.com/9/TK-2170&3170Brochure.pdf Of course you have to be within range of a NOAA station. Some places aren't covered, or not very well. https://www.weather.gov/nwr/ https://www.weather.gov/nwr/Maps Another advantage of a separate radio is you might have an active "Skywarn" group in your area. During extreme weather events this maybe a better source of timely weather updates. https://www.weather.gov/skywarn/ https://www.weather.gov/sew/spotter

It’s easy enough to find out once a person does the lookup the first time. The radio is required to have an FCC ID tag on the back to be legally imported/sold in the US. Then look up the ID on this site. https://fccid.io Type in the FCC ID and click the search button. Example for my TK-3170 HT Type-1 with ID ALH34713110. Then look at what’s under the Rule Parts in the grant. https://fccid.io/ALH34713110 Anything that shows Part 95 is certified for GMRS. In the example it’s Part 95A which is the pre 2017 rules, but still legal. The new rule part post 2017 in Part 95E. I do this for ALL my radios and keep PDF copies of the grants on file as part of the documentation set for that radio. That’s it.

Are you sure your dummy load is spec’ed for GMRS frequencies? Some aren’t and give really crappy readings.

It would be prudent to do some research first. Try to find user reviews online for the radio. Also if one has the technical background locating the service manual for the radio would be a good option. It would likely have the schematics. Looking those over would reveal how much frontend filtering is being done. For example I believe the Motorola XPR-7550e is one such example. Users swear by them and have very good frontend filtering and high sensitivity too.

A mobile doesn't have the antenna height advantage a base does. I'm thinking the FCC's goal is to limit the operational area by removing the antenna height advantage a base station has since they likely assume the communication would be between the base station and hand-held or other mobile stations belonging to the same licensee. They didn't want GMRS to turn into a "Ham Lite" type of service, which it seems to be doing.

Of course somebody will have to "volunteer" their time to maintain the list and weed out bad listings. This is were ideas like this usually fail nobody wants to put in the effort. Also some just don't care if their radio is Part 95 certified or not. A lot of users are operating older, and new, Part 90 only gear. So far the FCC doesn't seem to be interested in busting them. I'm not recommending the practice, but so far that seems to be the case.

That's a valid point. I think a fair number of GMRS users would agree given the limited number of repeater frequency pairs available. IMHO one should look at what the original purpose of GMRS was targeted at. You get a feeling for that based on the licensing rules, basically a family with parents and siblings. The typical communication would be limited to a small area. I don't think the intended operational vision was communication over large geographical areas, such as state wide or multi-state systems. A city wide or county wide system might be more reasonable. I'm neutral on the topic. I don't have a dog in the fight, not a repeater owner/operator. I'll let others do the heavy lifting. Advice given to new attorneys by the old experienced ones : "If the law is against you, pound on the law. If the facts are against you pound on the facts. If both are against you pound on the table."

Any publicly accessible radio service will have some degree of interference issue. The real question is just how much. Also remember not everyone is going to be on the air at the same time. If you're looking for a more robust plan then looking at several different radio services would be the route. Part 95 services would be GMRS.FRS, MURS and finally CB Radio. With the exception of GMRS you can buy radios for FRS, MURS and CB, use them with no license requirements. Then the final option is Ham radio Part 97. The later you need a license, each person, and have to pass an exam to get one. The Tech Class is fairly easy, however some people just don't want to be bothered. It does give you much more spectrum to operate in with and will greatly reduce the likely hood of interference. None of the two, Part 95 and 97, allow encryption. So, if you need to exchange sensitive information you'll have to either do so illegally with encryption, that's going to be a personal choice and nobody here will publicly recommend it, or find some other method to exchange the information, prearranged codes etc. I also would NOT depend on a repeater either, Ham or GMRS. Most are simply grid powered and will fail immediately on a grid-down condition. Some do have backup emergency power but may not last that long. Your best bet is assuming you're on your own using direct radio to radio, simplex, communications.

A lot of mutual interference and signal jamming. That of course depends on the length of the transmissions and power levels. Long winded communications using 50 watt mobiles would be the worse case.

I’m glad I don’t own and operate a functioning repeater system. I don’t need this kind of headache.

You can look at the attached data sheets. The down tilt is spec’ed at zero I believe. DB408-B Product specifications.pdf DB404-B Product Specifications.pdf

I think it means about the same thing. Yup, the tilt is done by altering the phasing of the elements a bit. I think it could be done by changing the length of the cable between the elements, or the element spacing, which likely will affect the match to some degree. Myself I wouldn't try messing with it. You need really good equipment to measure the field pattern and or simulation software to see the effects.

The antenna you mention in the title shows a "beam" tilt of zero degrees in the attached datasheet. I think you'll have to find another solution. DB420-B.pdf

I'll bet it did.

I hope it doesn't mutate in another cell phone store. At the end the local Microcenter computer store had more electronics parts for robot builders in one section than Radio Shack had in the whole store.

Then turned in to "cell phone shack." Then went bankrupt. I did hear they might be coming back in a few areas. I also remember going to Lafayette and Olson Electronics as a kid. They're gone too. Heath Kit is kaput. Lots of kids, and adults, got their first exposure to electronics building their stuff.

Use to be able to go to Radio Shack, Best Buy etc and they had rolls hanging on the display pegs in the TV accessories area. I think If one wanted to build a Slim-Jim I would try the 450 ohm ladder line. That's what the N9TAX ones use.

The RigExpert antenna analyzers are nice. The main attraction I have for them is the scan function. As a Ham you don't operate on just one fixed frequency. It's important to know what your antenna tuning looks like of the range you are going to use. I built one of the cheap 300 ohm TV twin line J-Pole antennas just for fun to see how well they work. These are the type recommended to have newbies build because they are simple to make and usually work well enough for an HT indoors or out on a field trip. The SWR is also reasonable. You ABSOLUTELY need the RF choke at the base of the antenna. I just used about 10 to 15 turns, single layer, of RG-58 rolled up on a 1 inch wood dowel pin. Good luck trying to find 300 ohm TV twin lead now days. Oh well. http://hamuniverse.com/2meter300ohmslimjim.html Antenna Scan Results (2M Roll Up Twin Lead).pdf

I used the Rigexpert AA-1000 to make my measurements. The antennas are a bit sensitive to the environment where you make the measurements so I’m not a bit surprised by slightly different results. Also the antennas are all hand built and tuned. That can result in differences too. I haven’t heard good comments about the Surecom meter. Most are about the same as yours, inaccurate results. But people like them and they keep selling.

I did a test on the N9TAX antenna a while ago. It’s similar to a simple Slim-Jim. The SWR isn’t outrageous on the GMRS frequencies. There are two versions. One tuned for MURS/GMRS. The other for 2M/70cm. N9TAX-MURS-GMRS-VHF Scan.pdf N9TAX-MURS-GMRS-UHF Scan.pdf N9TAX-2M-70CM-VHF Scan.pdf N9TAX-2M-70CM-UHF Scan.pdf

Is it the ProTalk version?

That’s nothing to worry about. You can use the antenna full time with that SWR ON GMRS. Most radios don’t start having issues until the SWR is 2:1 or higher.

That would be a nice feature to have on a radio. Maybe not at the end of every transmission. There is a feature on one of my digital radios to do it. But it has to be manually initiated through one of the menu selections every time I want to send it. Not very convenient.

Also consider the environment a typical HT is used in. hand-held, mobile with external antenna, hanging on a belt, stuck in a utility vest pocket. All those will really screw up the SWR. I was looking at the spec's for some of the hybrid RF power blocks used in many HT's and some mobile radios a while back. The HT one's I've seen they're rated to work up to a max SWR of 20:1!! Basically no antenna. It sort has to be that way due to the highly unpredictable environment HT's have to work in without failure. See example file attached. Look at the first page at the bottom. M67799MA.pdf