Lscott

It’s never to late to get started.

I used a BNC connector since I can find adapters to just about any other connector type. Plus BNC’s are constant impedance types. You can easily find BNC to SMA that screws into the antenna port on handheld radios. I also find heaps of short jumper cables at swaps with BNC connectors on the end. You want your Tech Class license the test is very easy with just a little bit of study.

I have a buddy that wants to put up a Ham 70cm repeater, about the same as a GMRS one but a bit lower in frequency, when the site is ready. He spent over $300 on a USED multi-bay folded dipole antenna for it.

I built almost exactly the same thing using some old PCB type BNC connectors. All the wires were soldered on, no screws. Surprising how well a 1/4 works, and the bandwidth I got was from 430 MHz to 470 MHz at the 2:1 SWR points.

As far as showing location on a radio’s screen I agree there with you. Now if the radio could communicate with a cheap GPS unit using a wired or BT connection that would be useful. The GPS unit would use the radio to broadcast its position, and on receive it would display the location of a remote unit. All the radio effectively does is provide the wireless link between two or more GPS units.

I was looking at the radio programming software for the Kenwood TK-3170 commercial radios, seems they are a favorite for GMRS use, has a number of options to setup GPS. If you have one of the radios and the software, Edit -> Optional Features -> Common Page 1, then enable "Com port 0" by selecting GPS for the function. The "Com port 0" is the side port where the speaker microphone plugs into while "Com port 1" is an internal port used for option boards when the cover is removed on the back side of the radio under the battery pack. Some of those option boards are for voice encryption using different methods other than simple voice inversion. To setup the GPS configuration, Edit -> FleetSync -> GPS. You can select which type of GPS data is sent. There also appears to be a simple beacon mode where you can set the interval the data is transmitted. One of the memory channels can be designated as data only. When the GPS data needs to be send the radio apparently will temporarily switch to that channel just for the GPS data. In the beacon mode this could be used for field location functions along the lines of APRS for Ham radio. Some of the other settings allow the dispatch office to request the GPS data on demand, or it can be sent at the beginning of or end of PTT, radio is polled etc. So at least on this radio the GPS setup is rather flexible. Other radios may be suited for just dispatch used as you mentioned.

Likely something like these Chinese duplexers? http://409shop.com/409shop_product.php?id=104460

There are “export” radios that do AM, FM and SSB now. Not legal on 11M but the engineering is already done. Just restrict the frequencies to the legal 40 channels and power limits the manufacturers are all set.

I think that's a mistake too. Consider the following. There are only 8 repeater channels for GMRS. For some, like me, there is only one active repeater in the area. Now if you have several radios with the GPS beacon going off on the repeater output frequency from radios in close proximity to you that would really screw with the reception. I've already had to put up with neighborhood kids on FRS radios on the repeater output frequency close by playing for several hours. You don't have the option to switch to another channel. It won't take too many to really ruin things. Worse somebody could be doing the beaconing on a repeater.

Or a fanny pack with a good LFP battery pack and adapter to use the PG-31 12 volt charger plugged into it.

So far the only Kenwood HT's I have that are usable on GMRS that seem to support the GPS speaker microphones are the TK-3170/3173, TK-3180 and TK-3360. The first 3 models seem to be a popular choice for GMRS. I'm sort of surprised the TK-3140 doesn't have any support. The TK-3360 is only a 16 channel radio but it does have the support. The older version of it, TK-3160, doesn't support GPS either. If the radio supports GPS data then under the "Optional" settings on one of the tabs there is a section for "Com port number". One of the function selections is for GPS.

I went through my electronic library of documentation for my Kenwood radios looking to see what data transmission ability they have if any. It looks like there are two speaker microphone models that have a built in GPS receiver, KMC-48GPS and KMC-38GPS. http://manuals.repeater-builder.com/Kenwood/kmc/KMC-38GPS_B51-8768-00.pdf http://manuals.repeater-builder.com/Kenwood/kmc/KMC-47-48GPS_B51-8930-00.pdf These should work with most models of Kenwood’s UHF HTs used on GMRS. The programming software for some of them has provisions for setting the radio up for TX’ing location data. At the moment I’m not sure which models. The NX-820HG mobile, not currently being used, I have has a built in GPS receiver already. So, if it gets approved, and finding one of the above allows you to use the soon to be expanded, hopefully, functions one can up grade their radio(s).

I think digital on GMRS is going to happen sooner or later. The real question is what protocol should be used. It might even pay to ask for a few more channels that are exclusive digital only while leaving the current set for FM to maintain compatibility with existing radios.

For some people it isn’t about the cost. It’s the satisfaction of building something yourself and the knowledge gained doing it. I’ve picked up cheap magnet mounts at swaps along with some generic whip elements that screw in to them. I wanted a cheap and quick 1/4 wave antenna for the Ham 1.25M band. Didn’t take much to trim one down using the antenna analyzer. Also doing some simulations it looks like a 1/4 wave could be made to cover the Ham 2M band and the MURS channels. The same with the Ham 70cm band and GMRS. The later I built using a cheap BNC circuit board socket and stiff bus wire. I can cover the frequency range of 430 MHz to 470 MHz with under a 2:1 SWR with a nearly 1:1 match at 450 MHz. I have one I use at the office on the top of a bookcase. Another one I used tie-wraped on the top of an old baseball type hat at the Dayton Hamvention a few years ago. Worked much better than the rubber duck antenna with the radio hanging on the waist. Sure I could have purchased them, but where’s the fun in that?

So now if FM is allowed on 11M some agreement would be needed to keep those users from interfering with AM and SSB users. That could be informal or put into the rules by the FCC. There is sort of one now where SSB is primarily used on the upper channels. I’m also wondering how much of the push to allow FM on 11M is a marketing thing by COBRA to protect their market share since Midland is pushing GMRS and the advantage of FM over AM in the overland community. By allowing FM that takes one of the advantages away Midland says they have by switching to GMRS. I don’t see the FCC allowing automatic TX of GPS data on GMRS/FRS. There aren’t that many channels to begin with to let them get cluttered up with periodic automatic data transmissions. For people that scan the channels it would be very annoying to have the radio stop every few minutes on random channels due to short burp of GPS data. Further the radio would need a mandatory BCL, busy channel lockout, to stop any interference when a channel is in use.

One can also try a corner reflector type gain antenna. Look for “Corner Reflector” in the menus and click on it. They’re not very big for the gain. http://arrowantenna.org

If you like to experiment and design antennas some good simulation software helps. I’ve used various versions of EZNEC+ up to V6 for a number of years. The software will be free starting in 2022. The guy who wrote it explains why, he’s turning 76 and wants to retire and doesn’t want to deal with it anymore. https://www.eznec.com/

I found using tooth paste as a VERY mild polishing compound works to get scratches out of plastic screen covers. Got out some mild ones on several of my used radios I thought would never come out. You should practice on a junk one to get the technique right otherwise you just end up with a lot of fine “stroke” marks on the screen.

So it's a one time deal? Listening all you want, then TX for 20 seconds and it dies never to work again?

Looking at the photo the plug is like several I have. The knurled nut on the end around the center pin likely unscrews. Typically there is a fuse in there. It might be the fuse is toast.

I thought of that too. There are plenty of radio shops that do just that. Some run a trunked repeater system as an extra cost option for their fleet radios. The appeal to the user is they don’t have the cost to install one or have to administer the system. With 5 or more repeaters in a trunked system on a tall tower you can handle a lot of users. The radio shop just assigns different customers to different groups. If I was renting radios I would make sure there was a requirement in the contract the radios must be wiped before being disposed of or rented to another customer.

What you said is true but that wasn’t my point. When the license expires that’s it, done. Now get a business only frequency. There should be no renewals. As it is most of the traffic I hear on FRS, family radio service, are business and rarely family or personal use.

That's what I suspect with a lot of the used HT's you see for sale. Companies upgrading their system, in the case of NMP you pointed out, to a digital system. They dump their old analog radios on the surplus equipment buyers market, who then turnaround and try to flip the radios for a quick buck.

Part of the fun collecting used HT's is trying to figure out who the previous owner/user was of the radio. Most of the time all you get is some frequencies listed, maybe the radio has provisions for a display so that might help. The Kenwoods I collect typically have an entry for 2 lines of 32 character data each that you can only see when reading the radio. Those are normally blank, but a few had something entered. A TK-3212 I acquired only had 14 frequencies in it along with the display names for each channel, nothing else was found in the code plug when the radio was read. After doing some detective work, a lot of searching through the FCC's database, I found an entry where "NMP" corresponded to the first 3 words in the company name, one letter each. The license it fell under was WPTP616. https://wireless2.fcc.gov/UlsApp/UlsSearch/license.jsp?licKey=2363642 https://wireless2.fcc.gov/UlsApp/UlsSearch/licenseLocSum.jsp?licKey=2363642 The frequencies also seem to match up. As you can see there is a unit 1 and a unit 2 in the FCC database, and in the code plug you see "U1 OPS", "U12 OPS", "NMP RAD", "NMP ADM" etc. Things looked like they all sort of made sense. NMP -> 9 Mile Point (Nine Mile Point) RAD -> Research and Development (For a nuke station you would figure something this would be going on) ADM -> Administration T/A A -> Talk Around Channel "A" The radio I got used off of eBay apparently was previously used at a nuclear power station. I joked with a few fellow radio buddies that I should check it with a Geiger Counter to see if anything happens. When companies dump used radios I'm surprised they don't get the code plug wiped clean. At lest in the above case it likely would have been advisable. Just enough info was there, some lucky guesses and detective work, and I'm fairly sure about where the radio came from.

The main issue with testing HT antennas is duplicating the coupling between the radio and the users body. Yes, the users body is part of the antenna's ground plane, and it makes a huge difference. I've done the experiments myself. Some of the antennas were screwed into a "SMA" magnet mount, yes they are around, then placed on a 30 to 40 inch square metal sheet for a ground plane. On a few of the antennas tested the SWR was over 3 or 4 to 1. Removing the magnet mount from the metal sheet and placing it on the back of my hand reduced the SWR to under 2:1 in some cases. The below links are what others have tried. https://www.hamradio.me/antennas/ht-antenna-comparisons.html https://reflector.sota.org.uk/t/antenna-testing-jig-swr/14791 https://www.ko4aje.com/ht_antenna_tests.html https://kd9nrt.com/2020/07/09/antenna-comparison-test/ http://www.km4fmk.com/NewAntTesting.html