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Lscott

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  1. Lscott
    Trimble Active GPS Puck Antenna

    From the album: Misc. Radio Gear

    I got a couple of Trimble active GPS antennas from a buddy who picked up a bag of them at a Ham swap really cheap. He gave me a couple. This is a Trimble model 28367-70. It's an old model design for use on the US GPS system only. I checked the antenna on a bench top and measured the current draw at around 20mA at 5VDC to the antenna supplied over the coax cable. https://www.zti-communications.com/documentation/GPSHardmountantenna_Literature.pdf There are newer models that will work with US and other GPS systems that looks very similar. I have no idea what these cost new, likely expensive. https://www.navtechgps.com/wp-content/uploads/AV28_DS.pdf The signal from US GPS satellites is rather weak and a preamp is recommended for more than a very short coax cable run. I want to use this with my AT-D578UV III Plus in place of the cheap included GPS puck antenna. The included one doesn't look like it's made for outdoors installation while the Trimble unit is. I needed to order a cable with a male TNC connector on one end for the antenna and a male SMA connector on the other end using 15 foot length of RG-316 coax to mate up with the radio.
  2. Lscott
    I think we’ll get digital in some limited form sooner or later on at least some of the GMRS channels. It might not necessarily be DMR.
  3. Lscott
    Likely happens in the morning and evenings. https://en.wikipedia.org/wiki/Tropospheric_propagation
  4. Lscott
    Some times there is some interesting stuff, even on the Ham repeaters. One night I was out walking after dark while monitoring a distant Ham 70cm repeater. Two guys chatted away for about 45 minutes to an hour about model railroading. It was refreshing to hear something not radio related in any way. I've heard topics from hunting, fishing to firearms at times as more examples. These are topics even non technical people can jump in and take part without feeling they are the outcasts. Maybe we need more of it, talking about every day stuff where the radio is just another means to facilitate the communications.
  5. Lscott
    Guy doesn't want to lower the price. He's selling it "For Parts or Repair" untested, no returns. For what he's asking on a long discontinued model is too much. If the output transistors are shot I might not find any replacements. Then I have an expensive paper weight. The one I have now had to get repaired some years back as it was. https://forums.mygmrs.com/gallery/image/415-amplifiersjpeg/?context=new The idea was to use them with an 11 element Yagi for sat communications on the UHF up link. The down link was on 2.4GHz, 24 DBi BBQ grill dish antenna, with a down converter to 2M. The mode was SSB on a linear translator. https://forums.mygmrs.com/gallery/image/469-antenna-collectionjpg/?context=new RF_Concepts_RFC-4-110_RFC-4-310_user.pdf
  6. Lscott
    Congratulations are in order then!
  7. Lscott
    The government claims they don’t have an “off switch” for the cellphone system. Anybody believe that? I don’t.
  8. Lscott
    I was just looking at an "untested for parts or repair" RFC 4-110 UHF amp on eBay. It's 10 watts in and 100 watts out. I have one now and was looking at maybe picking up another one I could use with a UHF power splitter/combiner to get 200 watts. I would need two identical amps to equalize the phase delay on each path for the power splitter/combiner to work effectively.
  9. Lscott
    If you have any local malls within a few miles you might pickup the mall security, assuming they are on FM some are using NXDN or DMR by me, for entertainment. At times you hear some weird stuff. I've monitored reports of food fights in the food court, kicking hookers out of the mall, adult activity in back seats of cars in the lot, running down shoplifters, vehicle repo people with computer controlled license plate scanning cameras driving through the lots etc. They even kicked some local TV news crews off the property because they didn't get prior clearance. It gets much more active near Xmas. A few times some people were "asked" to put certain unnamed items back in their car, at least they didn't call the local PD on them, because it was prohibited to have them in the mall. I'll leave it to others to figure out what those were.
  10. Lscott
    Well until they figure out that much power won't get them much beyond the radio horizon. No "channel 6 super bowl" on GMRS. Also UHF amps that can do 250 watts won't be cheap either, if you can find them.
  11. Lscott
    Just a bit more studying and taking some practice exams you'll get there. It doesn't matter if you pass by one question or get 100%. Once you have it you're done.
  12. Lscott
    Because the license fee was cheap, now good for 10 years, sort of cool to have and goes along with my Ham license. One other factor it’s not much trouble to get friends and family to get the license since no testing is required. Just fill out some forms and pay the fee.
  13. Lscott

    GRMS Needed?

    Lscott replied to a topic in Guest Forum

    If you don't think you need it then why are you here?
  14. Lscott
    Perhaps the FCC sees GMRS evolving into a "Ham Lite" type of service as a hobby rather than a personal use utility communication service.
  15. Lscott
    I did find the following on the NR-770 antenna. worth reading. https://www.hamradio.me/antennas/diamond-antenna-nr770hbnmo-with-k515snmo-mobile-antenna-review.html
  16. Lscott
    What kind of match did you get on the Diamond? The NR-770 and the SBB-5 look like a clone of the other one. Might even come off the same assembly line with a different label?
  17. Lscott
    For testing I’ve used a section of sheet metal about 36 to 40 inches square from the local hardware store specifically to simulate a ground plane when using a magnet mount. This way I don’t need to drag crap outside for testing. I can do it in the basement. The sheet metal section is about the area of a passenger vehicle roof. It’s big enough for a VHF through UHF antenna. https://forums.mygmrs.com/gallery/image/306-220-mhz-antenna-scan/?context=new I’ve also used some brass rods bent at a 45 degree angle for a cheap home made ground radial kit. The rods were held in place using a stainless steel hose clamp around a short SO-239 barrel adapter. My antennas are typically using a UHF mount. https://forums.mygmrs.com/gallery/image/268-ca-2x4sr/
  18. Lscott
    Thanks for everyone who responded. I might pick one of these up to experiment with it. The SWR numbers look encouraging.
  19. Lscott
    What kind of SWR do you get with the SBB-5 antenna on the Ham bands, MURS and GMRS? I'm still looking for a 1/2 wave ground independent antenna I can use for Ham, MURS and GMRS. I need something that will work on my luggage roof rack rail mount. The CA-2x4SR is a 5/8 wave design which requires a GOOD ground plane, which I don't have with the mount I'm using. https://forums.mygmrs.com/gallery/image/473-close-up-of-mobile-mount/?context=new https://forums.mygmrs.com/gallery/image/471-mobile-mount-with-antenna-rear-view/ https://forums.mygmrs.com/gallery/image/472-mobile-antenna-install-side-view/ Old installation on my Jeep. https://forums.mygmrs.com/gallery/image/259-ca-2x4mb-jeepjpg/ https://forums.mygmrs.com/gallery/image/282-ca-2x4mb-scansjpg/
  20. Lscott
    While not mounted on a travel trailer it is a portable antenna and mast system. https://forums.mygmrs.com/gallery/image/257-portable-mast-antenna-system/ This is compact enough to pack in the back of a small SUV.
  21. Lscott
    There are several license free radio services in the European Union, PMR446 (narrow band FM), Digital PMR446 (DMR Tier-1), dPMR446 (dPMR). These all operate from 446.0MHz to 446.2MHz. The Ham band there is only from 430MHz to 440MHz so it's outside of their segment but within ours in the US. The licensed power is only 0.5 watts like our old FRS standard. I would suspect hearing them around popular tourist destinations for international visitors. They likely would bring their radios with them unaware they would be operating in the middle of the US Ham band. There is a forum where EU radio use is discussed. Some of the old posts are fun to read. https://transmission1.net/viewforum.php?f=4&sid=a74e04a3a9d842dce32abec0669cc532 PMR446 White Paper.pdf
  22. Lscott
    Yes to both questions. You can start off with a cheap 1/4 wave magnet mount. The antenna will only be about 6 to 8 inches tall depending on the exact magnet mount used. The antenna will be short enough where you likely won’t have to worry about clearance issues parking in a garage, going through drive throughs etc. This will at least give you an idea of potential improvements with a better external antenna. https://forums.mygmrs.com/gallery/image/338-cheap-14-wave-gmrs-antenna/?context=new
  23. Lscott
    You can get a reasonable estimate for the SWR at the antenna end of the cable if you know the coax losses, from a chart of loss verses frequency for a known length of cable, and the forward and reflected power. You can calculate the loss for the exact cable length one is using at the frequency of interest. The cable loss allows one to calculate the power delivered to the antenna based on the forward power measured at the radio end. Also the reflected power measured at the radio end allows one to calculate the reflected power at the antenna end based on the cable losses. With both the calculated forward and reflected power at the antenna end of the cable is now “known” it’s now possible to calculate the SWR of the antenna itself. This saves the trouble of having to stick the SWR meter up at the antenna, which in many cases isn’t a realistic possibility. While not likely as accurate as a real reading it’s better than nothing.
  24. Lscott
    You might try something like these. They are rubber boots to protect the finish but also likely less slippy too. Most magnet mounts use a very thin sheet of plastic on the bottom. https://www.arcantenna.com/products/laird-antenex-gro-rubber-boot-for-magnetic-nmo-mount-vehicular-antenna https://strykerradios.com/product/sr-a10mm-magnetic-mount-protective-boot/ Note adding some thickness between the magnet mount base and the mounting surface will decrease the grip force. You may need a larger magnet mount base if you use the boot.
  25. Lscott

    BTECH AMP-U25D

    Lscott replied to WRQG450's topic in Guest Forum

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