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Everything posted by Lscott

  1. Yeah, I suppose one could simply buy a cheap Chinese dual band radio that does Ham 2M, MURS, VHF marine, VHF railroad, VHF NOAA weather channels etc. frequencies, then it can also do the Ham 70cm band, various government and public safety UHF frequencies, UHF FRS, UHF GMRS, UHF business band frequencies etc. for $25 through Amazon. Of course the people who buy it won’t know, or care, about the difference between a megahertz or millimeter. That happened with those combo FRS/GMRS radio a few years ago. They included clear instructions that a license was required to use channels above 14. Nobody cared and nobody bothered to get the license either. With your suggestion nobody is going to be dissuade by a warning tone, message etc. They’re going to press that PTT button all the same as proven by past experience. At least by requiring different radios the potential for mass interference is reduce because the hardware, along with the firmware, limits the operation to a particular service. As long as people act stupidly, or irresponsibly, you get these government regulations. Is it efficient? No. But that isn’t the aim of the regulations either.
  2. One other way to get some exclusivity is picking something like NXDN. Haven't seen any CCR's doing that digital mode yet. I have two radios for it already. One is an HT, NX-340U the other is a mobile, NX-820HG, a freebie from a buddy who didn't want it. https://comms.kenwood.com/common/pdf/download/05_nx240v_340u_K_1117_typeD added.pdf https://comms.kenwood.com/common/pdf/download/10_NX-720HG&820HGBrochure.pdf Both are the 400-470 MHz band split. There is only one repeater around the Detroit area that is listed as being NXDN enabled. In fact it's the only one listed in the whole sate using "repeaterbook.com" to check. https://www.repeaterbook.com/repeaters/details.php?state_id=26&ID=390 I know there is a pocket of NXDN activity in the Florida area. https://ni4ce.org/nxdn-digital-communications/ For P25 these are the only ones listed. https://www.repeaterbook.com/repeaters/feature_search.php?state_id=26&type=P25 The one closest to me I have equipment for it the machine listed for Warren. https://www.repeaterbook.com/repeaters/details.php?state_id=26&ID=276 So between the two modes, P25 and NXDN, nether one is widely used around here. The popular digital modes in Michigan are D-Star, DMR and System Fusion. There is a wide area coverage System Fusion machine in the down town Detroit area. The antennas are on top of the current GM head quarter building at 775 feet AGL. http://www.gmarc.org/wp/
  3. I guess I got lucky with the P25 radio I purchased. This is the original item listing reference number on eBay. 294333278387 I think you can go here and enter the above number. That should bring up the original listing. http://www.watchcount.com/ I spend a lot of time checking eBay using my saved searches to see if anything new pops up for the models I'm looking to buy. If it looks like a good deal I have to spring for it quick before somebody else notices it. That's how I snagged a TK-D340U 32 channel Kenwood DMR radio for around $40 to $50. The same thing happened with a Kenwood NX-340U 32 channel radio for NXDN for $50. Never saw any deals that good since.
  4. True. The P25 activity might pick up with time. I'm guessing that's simply because DMR is becoming more popular. Once people get bored with it they'll jump on the next thing that looks cool and carries some prestige as being unique or rare. Then the cycle starts all over again with repeater networking etc. P25 might also become more popular when more of the business, and particularly government users, switch over to P25 Phase 2 equipment. All the P25 Phase 1 stuff will get dumped on the surplus market.
  5. In general the FCC doesn't like combing different services together. In the case of FRS and GMRS they had already screwed that up years ago by allowing the marketing of dual service FRS/GMRS radios. Almost NOBODY ever got the GMRS license when purchasing those combo bubble-pack radios. The FCC had to throw in the towel and make what was already common practice legal by changing the rules back in 2017/2018. Then they could wash their hand of any enforcement issues.
  6. Thanks. It's good to get another perspective on things. I guess if there isn't going to be much P25 activity around by me or any repeater linking the radio makes for a really nice fancy analog FM one. 8-( I was watching a really short video earlier where a guy was using what looked like a almost new NX-300 just for GMRS while ignoring the digital half, NXDN, of the radio. https://comms.kenwood.com/common/pdf/download/02_NX-200G&300GBrochure.pdf
  7. Actually FRS/MURS would be a better fit. Just have to use a fixed mount antenna. Most of the channels on FRS are already 2 watts. All the MURS channels are also 2 watts. Both services are license free provided one uses FCC certified radios. This would give the average everyday user up to 27 channels split between FRS and MURS. This allows the user to pick which band works better under the current conditions without carrying two radios or having to pick one over the other, and maybe getting poor results because it was the wrong choice. There is a reason why dual band VHF/UHF radios are so popular in the Ham world for example.
  8. Oops. The Kenwood models should have been the NX-200 NX-300 radios. https://comms.kenwood.com/common/pdf/download/301_NX200-300.pdf Motorola https://www.motorolasolutions.com/content/dam/msi/docs/business/products/two-way_radios/portable_radios/wide_area_large_business_portable_radios/xpr_6500/_documents/static_files/mototrbo_portable_spec_sheet.pdf
  9. I’ve been looking at picking up some more commercial radios, analog/digital, for Ham radio. Some models I’ve been looking at are Kenwood TK-200 and TK-300, then I was looking at the Motorola XPR-6550’s (VHF/UHF) types. I have a buddy that has the XPR-6550. The older Kenwood stuff I’ve had good luck finding the programming software. I also have the accessories including the programming cables to fit them from the other radios I have already. These will work on the models I’m looking at. The Motorola radios I have zero for them. I would have to make an investment in cables, battery packs and chargers. The software is my major concern. I need to find it really cheap or less. Further it has to program the radio in both wide and narrow band modes. I also don’t know if you can force the radios to go out of band like the Kenwood radios if the band split is above the Ham band. For example the Kenwood 450-490 band split I can enter, with a warning, frequencies below 450 and get the radios to work down to 440, maybe a bit lower. I stumbled on a review of the XPR-7550 and XPR-6550 on YouTube by a Ham for Ham applications. The comments about the XPR-6550 being limited to 16 channels per scan list seems very limiting for me. I do a lot of passive scanning with my radios, frequently with more than 16 channels being active. The XPR-7550 apparently doesn’t have that limitation but costs significantly more than the XPR-6550 and used some kind of weird antenna jack. The XPR-6550 I can find on the big auction site for $100 more or less in good condition if I shop carefully and wait for a good deal.
  10. Which one did you get? My last major purchase was a TK-5320 analog/P25 UHF radio. There’s hardly any P25 activity in my area, but like you said for experimenting. https://pdfs.kenwoodproducts.com/18/TK-5220&5320Brochure.pdf
  11. This why I use the custom boot up screen option in any of my radios that have the feature. I put my call sign on that screen. Nothing like turning on a stolen radio and seeing the owners ID on the screen. If the thief doesn’t know what it is they might show the boot up screen in their on-line ad. Or whoever buys it will recognize what it is, lookup your callsign up on the FCC database, get your address and contact you if they have any suspicions about the radio’s sale. One other thing on my Kenwood commercial radios there are 2 embedded message blocks, 2 lines of 32 characters each, you can type in any info you want. I use my call sign and home address in it. One is normal the other is password locked against editing. These message blocks get written to the radio as part of the code plug. When the radio is read you can examine what’s in those message blocks. I highly recommend people use this feature if you have it. Every used commercial radio I buy the first thing I do is read out the current contents and check to see what’s in that embedded message block before reprogrammed them. That code plug I save on disk. While the above might not be any guarantee you’ll get a stolen radio back, it will improve the odds.
  12. Yup. The question was already answered. If there is going to be a standard highway/road channel, where one has been proposed and used for a while, we should stick with it. Trying to establish another one just confuses people and likely guarantees nether get used much. Unless there is a very good reason to change it I don’t see the point trying to establish something different.
  13. https://forums.mygmrs.com/topic/1847-any-suggestions-for-a-highway-channel/
  14. The location where you use the radio can make a huge difference in your reception. Try moving around and even try outside.
  15. Looks like the default settings when programming in a new memory channel. I’ve seen this on some of my other radio’s programming software.
  16. To change things up a bit, I would like to get some info on talk groups. At one point “RepeaterBook.com” would show which talk groups are accessible through a given repeater. Lately I don’t see this listed anymore on the details page for a given repeater. I can find lists of talk groups, seems the various modes are tending to use the same group ID’s for the same functionality and locations, at least for DMR and P25 I’ve looked at so far. But that doesn’t help if the repeater doesn’t support all of them. I’ve also seen recommendations to use my DMR ID, CCS7, for my P25 ID. For example I’m building a code plug for a P25 radio, TK-5320, and I wanted to test the audio by using the “Parrot” talk group on a local repeater. Looks like I can activate the repeater but nothing else happens. I don’t know if it’s my problem or the repeater doesn’t support that function/talk group.
  17. The brass rod will work just fine. Being rather stiff it won’t bend out of shape from handling the antenna, that’s the advantage. One other thing, the larger diameter wire or rod tends to increase the bandwidth too. That means you might get away with an antenna the works over the range of two services, like Ham 70cm and GMRS, or Ham 2M and MURS. Manufactures typically spec the usable bandwidth of their antennas at the 1.5:1 SWR points. Practically most radios are OK up to a 2:1 SWR. The higher the SWR of course results in a larger usable bandwidth. Go ahead build some antennas, experiment, do some reading and ask questions. It’s a great way to learn, and you can end up with a usable design that you hand crafted yourself!
  18. You have some points. The dual channel direct mode likely works well enough otherwise the more established name brand manufacturers wouldn’t be offering it. I have a Kenwood TK-D340U that has it. I haven’t really played with the radio, need another radio with the same feature to test it out. At least a model and manufacturer one can reasonably expect the radio to be designed right. https://comms.kenwood.com/common/pdf/download/DMR_TK-D240V_D340U_K_letter_1124.pdf The switching between TX and RX should be very fast using TDMA since the frequency doesn’t need to change, unlike FDMA modes. If the frequency needs to change then you have the pull in lock time for a PLL type frequency synthesizer. A DDS doesn’t have that problem, but still has to be programed through the micro which does take time, maybe not as long as a PLL design. If there is a big delay between switching TX/RX I suspect it’s due to other issues unrelated to the electronic power switching.
  19. If it isn't part of the standard it could be at some future point in time. The ability to do single frequency repeater operations is just to good of an idea to ignore. Designers haven't used, mostly, relay switch for low to medium RF power in years. Looking at just about every HT for example they use PIN diodes to do the RF switching, which can be done much faster than any mechanical relay could do. https://electronics.stackexchange.com/questions/166579/pin-diode-t-r-switch-for-use-with-rf-power-amplifier https://www.richardsonrfpd.com/docs/rfpd/High_Pwr_Sw_Des_Guide.pdf The rapid switching required due to the used of TDMA shouldn't be a problem. Also I think the Anytone D575UV mobile has the single frequency repeater function in the firmware. https://www.youtube.com/watch?v=p2mnsOla5fE https://www.youtube.com/watch?v=lhX1_mEpJq0 Also with DMR you have DCDM, dual channel direct mode. This is where you can have two simultaneous voice communications occurring on the same frequency without the requirement of a repeater to sync the two time slots. the radios will figure it out on their own. Examples. https://www.mototrbo.sk/en/mototrbo-systems/simple-connection-direct-mode-gb https://ecfsapi.fcc.gov/file/6512562680.pdf https://mra-raycom.com/wp-content/uploads/simple-file-list/Specifications/DMR-Product-Overview.pdf
  20. The charger is for mobile use. I have several of these. They work with multiple Kenwood Ham HT’s. I use this with a fanny pack carrying a lithium iron phosphate pack cabled to a matching socket for extended run time. The radio I used for years, and the very first one I purchased new, when I first got licensed about 20 plus years ago was a Kenwood TH-G71A dual band. I still have it, serviced a couple of times over the years due to a failing volume control. I recently picked up a used one at a swap in very good condition for $45 as a “spare”. My original one I did the MARS/CAP mod on it years ago. The used one I got I left unmodified. I also have a collection of speaker mics, head sets etc. So far the best for walking around and monitoring is the “D-ring” ear speaker with the lapel PPT/mic combo. I use that when I’m out at the mall waking around with the TK-3170 hanging on the belt under a long loose fitting shirt to hide the radio. I run the cable up under the shirt. The only thing you see is the ear mounted speaker. Nobody even bothers to look or stare, including the mall security cop, who I monitor all the time. Likely think it’s just some kind of cellphone accessory.
  21. I would think any digital mode that doesn’t use TDMA, like DMR, would work in a mix mode environment. I think FUSION uses FDMA as well as some less used modes like NXDN and P25 Phase 1 radios. Supposedly P25 Phase 2 will be TDMA, not FDMA. One thing that has me thinking about DMR is the ability to run a single frequency repeater, which doesn’t require any cavity filters. That’s only possible because of the dual time slot nature of the transmissions. You can run two independent voice communications on the same frequency, each using one of the two available time slots. One slot is used for the input to the repeater (RX) while the other time slot is used for the output (TX). Since the radio is never transmitting and receiving at the same time, only one time slot is active at any moment, the need for duplexer cavity filters is eliminated. That makes for a very easy repeater to setup. Set your operating frequency, connect to the antenna of your choice, switch on the single frequency repeater mode and let it rip.
  22. I only got one with a speaker microphone, battery pack (the lower power 6VDC one), case for expendable batteries, antennas and charger. All for $15 with original documentation and box. The radio looked like it was treated well, minimal scuffs and scratches and seemed to work when he showed it to me. So far I haven’t done anything with it yet. It looked like such a good deal for the price I couldn’t resist. The guy was selling it because he went with a newer analog/digital radio and had no use for it any longer.
  23. I know it’s not legal for Ham and GMRS. If I even got one I might sell it. The D878UV claims to use DES-256 encryption on DMR I believe, and is already built in to the radio’s firmware, nothing else to buy or license. On some of the analog Kenwood’s, that take optional voice scrambler option boards, require a few electrical mod’s to use them. Typical a resistor or few need to be removed. They are not just plug and play with a check mark in the CPS.
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