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Lscott

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Everything posted by Lscott

  1. Lscott
    That's a very good question. Lately the auto manufactures want to eliminate AM radios from their vehicles. I strongly suspect there is much more to it than a simple cost cutting measure. I'm even more suspicious when an EV is involved. My professional work experience involves designing high power switching inverters for metal heating at high frequency. I know first hand just how much electrical RF trash these things generate. I also consult with a buddy who does work over the years on EV motor drives, very similar in design principle to what I do. In his case they have to do extensive EMC, electromagnetic compatibility, testing. The AM radios are amplitude modulated receivers in the frequency range of 550KHz to 1600KHz. Some of the EV motor drives operate up to 150KHz in some cases. The harmonics from the switching waveforms can easily end up in the AM radio broadcast band. I think the manufactures just want to eliminate the AM radio option rather than spending gobs of money trying to shield the motor drive inverter electronics so it doesn't trash the radio in the dash. If it's not there then there is no complaints they have to deal with fixing.
  2. Lscott
    See your private messages. I sent you the info on how to do it. I've had other password locked radios off or eBay. It sucks when you get one unless you have a way to remove them.- Oh, the TK-3173 is a very nice radio for GMRS. Its basically the same, uses the same software as the TK-3170, but it also includes trunking. If you have a Ham license you can program out of band frequencies in the radio, the software with generate a warning but will accept the entry, allowing you to put in some Ham 70cm repeaters.
  3. Lscott
    After doing some reading I would not recommend a TYT TH-9800 radio for Ham or GMRS. While they are a neat radio they apparently suffer from various issues. One seems to be failure of the audio amp chips from an over voltage condition. I have a buddy and his just had the audio die on one side the other week. See the linked YouTube video for one such failure and how the tech fixed it and added the parts that TYT left out to save money. https://www.youtube.com/watch?v=X9HgrYCAzo8
  4. Lscott
    Here’s one example of an open source codec. https://www.rowetel.com/wordpress/?page_id=452 Note that the open source mode dPMR has bits that tell the RX radio what codec is in use. The mode allows up to 4. One could be an open source version like the above. See attached file. dPMR MoU tech lib Voc Bits V1 (2019).pdf
  5. Lscott
    I’ve posted this before. You might want to download it for a good read if you haven’t seen it before. GMRS Digital Voice - 20231127.pdf
  6. Lscott
    I'm on another forum where somebody asked about getting the frequencies used on an NXDN trunking system from just the radio handset. They wanted the frequencies used just to scan. One poster said that's impossible without access to the system key file, available only from the trunking system admin. It just so happened one used radio I purchased came programed from a trunking system. The normal radio software won't read it without the key file. Well, I had a hacked version of the software that allows me to read the radio and save the info as a service file. I posted screen shots of the frequency lists etc. just to make a point that nothing is hack proof or secure as you would assume as far as the trunking info goes.
  7. Lscott
    Yup. Many radios have been wrecked by application of the "Golden Screwdriver".
  8. Lscott
    When one of the young generation tells an older person they don’t know what they are talking about and gets reminded that eating Tide-Pods is not a good example of a high IQ. My question to them is what is their favorite flavor of Tide-Pod?
  9. Lscott
    Well the national organization that represents Hams, ARRL, has its roots in just such an activity. ARRL stands for Amateur Radio Relay League. In the very early days of spark transmitting messages were passed from station to station cross country. That was just about the only way to communicate long distances in those days. Even today there are emergency Net practice sessions on the VHF/UHF Ham bands, and on some HF ones, where one of the activities is traffic passing of messages.
  10. Lscott
    That’s why some expensive high gain repeater antennas have a “down tilt” specification. These antennas are specially designed to direct a bit more of the power downward closer to the antenna site. That improves close in repeater coverage. https://www.repeater-builder.com/antenna/downtilt.html https://www.kpperformance.com/Antenna-Downtilt-A-Practical-Overview.html
  11. Lscott
    What you learn quickly the real circuit is not what the schematic shows. When you include all the parasitic elements it’s gets a lot more interesting. The higher the frequency or when transient events are important you can’t neglect them.
  12. Lscott
    Ok.
  13. Lscott
    You forgot about the necessity of cutting off those crummy F-connectors, replacing them with “N” type or PL-259, if you can find any that fit that coax size, or finding the correct adapter. I think you’re better off installing the correct antenna and coax and save yourself the extra hassle.
  14. Lscott
    If you're definitely using your GMRS radio in Canada then you should be aware of the Industry Canada, their FCC, rules. They are closely similar to the US FRS rules. Per the Annex E specifications GMRS radios in Canada are restricted to no more than 2 watts ERP, effective radiated power. That's a significant restriction. Canada GMRS-FRS Rules.pdf Canada FRS - GMRS Channels.pdf Canada Annex E - GMRS and FRS.pdf
  15. Lscott
    If you’re going to do any significant driving through the west side of Canada you may run into what are called “radio controlled roads” which are on VHF. That might be more of a use to you than the Canadian version of GMRS. Canada VHF LADD Channel List .pdf
  16. Lscott
    It would be a very good idea to wait a few months on buying a TH-D75A. Let everyone else do the beta testing. By then Kenwood should have a good idea where all the remaining software and hardware bugs are and have a fix for them. I wouldn’t be surprised to see the radio go through several hardware revisions before getting to a stable design.
  17. Lscott
    There is nothing in the rules that requires this, but it's the general practice. https://www.customsmobile.com/regulations/title47_chapterI-i4_part95_subpartE_section95.1763 A few repeater owners have selected a frequency pair from the 462 and 467 groups that are NOT an exact 5MHz offset. That was done to discourage some users, with fixed programed frequencies in their radios, from accessing the repeater. While that will "tie-up" what amounts to 2 "repeater channels" and may not be well received by other repeater owners it's not illegal under the current GMRS rules. https://wiki.radioreference.com/index.php/Offset Same with tones. A few owners have required the use of MDC to access the repeater in an attempt to limit unauthorized access. Most of the common Chinese radios can do CTCSS or DCS but not MDC, thus cutting them off from the use of the repeater. The are a number of the more expensive new/used commercial grade radios do include MDC functionality other than Motorola. See attached example brochures. https://en.wikipedia.org/wiki/MDC-1200 TK-2360-3360 Brochure.pdf TK-5220_5320 Brochure - 1.pdf NX-1200_1300 Num 1.pdf NX-220_320.pdf
  18. Lscott
    Or GMRS users simply don't need the feature enough to bother commenting to the FCC about it.
  19. Lscott
    It's bad enough people are trying to poke at their vehicle's touch screens, or playing with their smartphones, while driving. Do we really need another distraction for the driver?
  20. Lscott
    You very likely can get a purpose built repeater controller for a lot less money unless you "happen" to have a PLC laying around someplace. Otherwise the cheapest thing you likely can use is like the example linked to below. https://www.robotshop.com/products/ardbox-plc-20-analog-modbus-industrial-arduino-module
  21. Lscott
    I think if one wanted to know your location in an urban area using an app on the smart phone seems like a better idea. At least the location data can be overlaid directly on a map using a device most people already own. Using an HT or mobile radio alone one would still require some method to plot the GPS location so more hardware would be required anyway. The above point also applies while out "in the woods" too. I guess one would have to store the maps on an external device first then interface the radio to it to plot the GPS location being sent it it. Apparently there are some devices that can do both in one box but they likely aren't cheap. https://g.factoryoutletstore.com/cat/31220/rino-.html
  22. Lscott
    The FCC screwed up when they allowed the sale of combination FRS/GMRS radios before the rule changes in 2017. The idea was if one wanted to use the GMRS specific, at the time, channels one would have to get a GMRS license. Well, almost nobody bothered. So, when the rules were changed in 2017 the FCC had to do something about all the existing radios out there. They simply changed the rules to make those combination FRS/GMRS radios FRS only and legal to use as is. However the channels you pointed out sit between the main GMRS repeater input channels, which use a 25KHz channel. The FRS channels, 8-14, where kept at very low power and narrow band since they partially overlap the main GMRS repeater channels. The idea was to minimize the interference they cause. At the time FRS was limited to 0.5 watts and narrow band, 12.5KHz channel, so keeping the restrictions didn't require any changes to existing radios. As you pointed out for FM use they are basically useless. Many GMRS specific radios don't even include them, noticeably on mobile radios. So practically speaking GMRS really has useful access to only 15 channels. You might ask is there something that those channels could be used for? Maybe, but that's a topic for another thread, which if you look you'll find on the forum discussing adding channels to GMRS. FRS-GMRS Channels Layout.pdf
  23. Lscott
    Have you considered using any of the license free MURS radios? While limited to 2 watts max at VHF they do a bit better in terrain that's a bit hilly and tree covered. https://en.wikipedia.org/wiki/Multi-Use_Radio_Service Some examples of MURS radios. https://www.retevis.com/murs-radios https://www.buytwowayradios.com/business/murs-radios.html There is also a mobile magnet mount antenna that is usable for both GMRS and MURS in case you decide to carry both types. https://dpdproductions.com/products/dual-band-gmrs-murs-mobile-antenna
  24. Lscott

    Lscott commented on TheNevilleKid's gallery image in Members Albums Category

    You'll end up like me with a bunch more radios in your collection. It's addictive.
  25. Lscott
    I checked mine, V4, and the attached photo are they only frequency options shown for the TK-880 mobile radio.
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