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WRAF213

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WRAF213 last won the day on March 5 2020

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    Ventura, CA, USA

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  1. Coverage maps are hard because GMRS is a line-of-sight communications service. There will be spots where you can be less than 5 miles away from a hilltop repeater and not be able to open its squelch, and there are spots where you're scratchy into a repeater that's 100 miles away. Coverage maps can be very reliable tools if both the mobile station and repeater's powers, losses, and thresholds are properly entered; the correct antenna patterns and heights are used; proper statistical losses are taken into account; and an effort is taken to ensure the topography in the mapping software matches real topography. In my experience, none or very few of these tasks are done when generating a coverage map. Real coverage tends to be much less than the modeled coverage, typically because statistical loss has a huge effect (mobile coverage requires staying above the signal threshold more than n% of the time (I usually model at 70% or 87% depending on band), while spot coverage (often used by default) assumes you're standing still in the peak of a fluttery signal), your antenna (especially if portable) probably has less net gain than whatever mobile station the map-maker simulated coverage with, site noise is a very real thing that will reduce repeater sensitivity, repeater owners may not realize that they are using a directional antenna or tower mounting position, and not many repeater owners are willing to admit that it's possible to have 4 dB of loss between the transmitter and the antenna. Repeater owners and users also like to see good coverage come out of the simulations, regardless of actual coverage, so there's even incentive for misleading coverage maps. So, there's a lot of ways to alter the coverage depicted on a coverage map, and there's so much room for variation (about 25 dB worth) that it's not possible to make repeater-to-repeater comparisons unless the same person made all the maps with correct information. And unfortunately, it isn't possible for MyGMRS to generate the coverage maps accurately, as there's a lot of room for variation with repeater hardware (dinky little solar power repeater running 5W into a counterfeit Nagoya antenna duct-taped to a chain-link fence, vs. someone running 50 watts into a solid duplexer with preamplified receive and a 10 dBd gain antenna) and repeater locations on the map are not always accurate for various reasons. So, we just generalize coverage into a circle around the repeater's map position. It's easier for a repeater owner to estimate how far their repeater can cover towards population centers than for the owner to generate coverage maps that are correctly parameterized. It's easier for MyGMRS to handle circular coverage patterns than the rasterized geo-referenced images outputted by coverage mapping software. Radio coverage in general should be taken with a heaping handful of salt due to the wide degrees of variability that are out there, and instead test your actual coverage with a second radio or a friend. And if you know or learn mapping software such as Radio Mobile, you can even make your own coverage maps for estimation if there's enough information about a repeater's location in its MyGMRS listing.
  2. Unfortunately, zero type acceptance on the RT97, despite proudly displaying the FCC logo...
  3. It depends on how the repeater is set up. Some have a really sensitive squelch threshold, others require a lot of quieting before the repeater unmutes. Some repeaters also have insensitive receivers, resulting in you hearing the repeater much better than it hears you. Combine a touchy squelch with a deaf receiver and you'll have a repeater that you sound very scratchy into, but you'll always hear the repeater's tail clearly.
  4. And with the current system of 'hide offline repeaters' and 'hide outdated listings', a lot of the repeaters that have been around for a long time get hidden by those settings and mixed in with the dead repeaters. There absolutely needs to be a user-reported repeater status function. Most of the repeaters in my area aren't actually listed on MyGMRS, and those that are listed are inactive or offline. It makes frequency coordination an absolute pain. I'd consider the output tone 'public' information as well since it typically identifies a system uniquely within an a particular area and channel, and gets transmitted along with the carrier. Keeping that information hidden when reading a 'found repeater' report makes it hard to tell if that reported repeater is actually the one you're hearing. This could also help with people claiming ownership of repeaters they do not actually own. When I first got my repeater, I used a particular frequency and tone that was in use nearby. Due to California's highly variable topography, I couldn't hear the incumbent user's repeater when I was doing frequency surveying, but the coverage area overlap was a serious issue. I had to reprogram the repeater and several radios, and get the cavities re-tuned to a different pair, because the only people currently allowed to report a repeater's existence are the owners. Many repeater owners don't want their repeater's existence or site location to become public knowledge. I do believe it's against public interest to enable that behavior, since the 8 GMRS channels are all accessible to the public and there is no right to privacy on what information is sent over the repeater's output channel. However, there needs to be limitations on access to what specific information can be seen by other users. Frequency, output tone(s), general location, and CWID (if any) can all be narrowed down quickly with a receive-only station or two, and it may also be possible to determine whether a repeater is open or not (only the owner can give the final verdict). The user-reported repeater entries should be marked separately from owner-reported entries since there's no way to attest to the accuracy of the information, and there needs to be some inquiry as to whether there's an abuse potential for such a system that would make the risks outweigh the benefits. Personally, I think there's much more benefit than risk, and Repeaterbook uses a similar system for their ham repeater listings. Over there, change history isn't made public (allowing non-public information accidentally contributed to be removed), and the repeater owners can hide all information beyond frequency, callsign, public/private system, and on/off-air status. Unlike ham bands, there's heavy frequency reuse on GMRS because 8 channels is a lot less than several hundred channels, so there needs to be a more granular way of identifying repeaters beyond using the frequency alone. I think it could also be worth allowing 'found repeater' reports to include general comments, such as hangtime duration, activity level, or peculiarities with the repeater; but anything suggesting the input tone should be censored.
  5. The 771 isn't resonant on GMRS, it's typically resonant on 440 to 450 MHz for UHF. I'd expect SWR at or above 2:1 or 3:1 on GMRS frequencies. I lost the sweep results on mine but I have posted about it earlier. As a rule of thumb: longer, high-gain antennas have less bandwidth than shorter antennas.
  6. WRAF213

    CQ on GMRS

    If I'm working simplex, I'll usually say something like "WRAF213, on 675" for the main channels, or "WRAF213, on channel 1" for the interstitials. It's a good idea to say which channel you're on so folks using scan will be able to find your transmission easily. On repeaters, I'll include the repeater name/tone when calling someone, otherwise I just drop in my callsign or even just the suffix. If I needed to hear a monologue when someone hops on a repeater, I'd just go back to the WIN System. I hang out on channel 1 a fair bit, but only pipe up to help people who can't get radios talking together; SDR instantly tells me their channel settings, and I only talk to the parents/adults. I scare the crap outta all the kids in a 5 mile radius whenever I get on that channel, though. It's much more fun from hilltops.
  7. Part of getting Part 95 type acceptance is not having amateur frequencies available on a GMRS radio. Modifying the frequency capabilities of the radio to gain access to 70cm or whatever band would void the Part 95 type acceptance. This should also apply to Part 90 use on GMRS as well, but it's a silly rule best ignored. Part 90 operation can occur in the 420-450 MHz band (every so often you'll see a STA for that). Unfortunately, the rule specifically mentions the Amateur Service. The intent of the rule is both to segregate the services by license type and to ensure the radio is type-certified over its entire operating spectrum.
  8. The UV-5R, containing controls to operate the transceiver, is intended to be held. It's not protected under Nevada's hands-free laws. Whoever initiates the traffic stop might use their discretion to not issue a ticket for a radio on the hip or in a center console as the radio isn't readily accessible, but if you get caught it's probably for taking your eyes off the road to change channel or something. Most commercial and CB radios (designed for road use) meet those legal requirements, while most ham and Part 95 GMRS radios (designed for operator convenience) do not.
  9. Look at how little filtering the RT-22 has. There's all sorts of unpopulated pads on the production model that aren't on the FCC submitted model. I bet those harmonics aren't 50dB down on production models. Again, you're in a highly unconventional RF environment, RF power coming from the Candelabra transmitters through a typical UHF passband (370-530 MHz) should be in the ballpark of 0dBm. Most people are around -50dBm. That's a HUGE difference. That said, CCRs aren't meant to be used on fixed antennas; they're designed to be used as portable radios. Most handhelds will show measurable desense on a high-gain base antenna, CCR or not. The typical CCR construction with a wide-open frontend happens to have a lot more desense. In open spaces away from other transmitters, they have a slight advantage due to less filtering loss. They have their place, and that's on-site business use on the hip; can't desense if the strongest transmitter is the repeater you're using. They also work good enough for amateur use that people keep buying them. Few people in reality will cite receive performance as a reason to upgrade from a D878UV or something to a Motorola or Kenwood, it's mostly for audio quality. Over here, where the noise floor is high on VHF, I get better coverage on GMRS than MURS, and better 800 MHz Part 90 reception than 460 MHz Part 90 reception. In my experiences with line-of-sight conditions, the higher gain from UHF antennas gives better audio (helps to make up for deep fades, which are briefer on UHF), while in mobile-to-mobile situations with some separation VHF has an advantage in punching through terrain. UHF has much better spot coverage. For mobile-to-mobile operation, ~50W out into a gain antenna on GMRS should give universally better coverage than your Part 95 compliant MURS setup. Portable-to-portable simplex will be much more variable due to terrain. Noise floor is also an important consideration in urban environments, and lower frequencies will have more noise than higher frequencies.
  10. Can you get an audio recording of it? I'm not in the area, I'm just wildly curious.
  11. My personal repeater runs split tones, and several other private repeaters around me run split tones. It's almost exclusively commercial radios being used on those. That said, nearly all of the GMRS activity happens on repeaters without split tones. Having that capability isn't essential for a first radio, but a need might arise later on.
  12. For folk that "can't stand talking to the same people every day", there sure are a lot that get real angry if someone tries to enter a conversation. Most 2-meter repeaters and open, linked 70cm repeater systems around here are welcoming of new users and make it pretty clear that they are. It's just a friendlier place to start out on a $25-$50 handheld.
  13. UHF connectors have been around for almost a century, back when VHF was called UHF because we didn't have enough frequencies above HF to need a distinction. They're cheap to make and handle a lot of power (a well-constructed connector will handle full legal power on HF amateur), so they remain popular. Unfortunately, they remain popular on radio equipment designed for frequencies well above what the UHF connector is designed for. Avoid the connector wherever possible on 220, 440, and GMRS equipment. N is a much better connector both in RF performance and weather resistance. Regardless of connector choice, pay attention to your connector's plating as well to avoid PIM. PIM shouldn't matter a whole lot unless you're full duplex, transmitting on two radios simultaneously, in a generally poor RF environment, or monitoring open channels for weak signals (like with emcomm).
  14. UHF connectors shouldn't even be used at GMRS frequencies since they don't present 50 ohms above 100ish MHz.
  15. I've gone through enough Flex-Shot to name a radio after it.
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