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Lscott last won the day on July 29

Lscott had the most liked content!

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    Design high power AC high frequency inverters for induction heating of metal parts. Have degrees in Electrical Engineering, Math and Computer Science.

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  1. 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.
  2. 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.
  3. 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.
  4. 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.
  5. 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.
  6. Likely something like these Chinese duplexers? http://409shop.com/409shop_product.php?id=104460
  7. 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.
  8. 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.
  9. Or a fanny pack with a good LFP battery pack and adapter to use the PG-31 12 volt charger plugged into it.
  10. 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.
  11. 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).
  12. 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.
  13. 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?
  14. 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.
  15. 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
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