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axorlov

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Everything posted by axorlov

  1. With a human dispatcher, yes, certainly. With a simplex repeater (seems to be not allowed by Part 95 rules), yes. To make a regular repeater one would need two radios, diplexer, repeater controller, etc..
  2. I'm reading the same lines, and my interpretation is there is a single $35 fee. We will see soon. At any rate, $7/year vs $3.5/year is not a big difference. Cost of good quality radios dwarfs this cost.
  3. The NATO phonetic alphabet use is not required and not expected. Just spell out callsign in English.
  4. Congrats! I'm not sure about 880 V1, but V2 tunes into the repeater part of Ham band without problem (only warning pop-up in the software). In the place where I live, San Francisco Bay Area, 70cm repeaters are quiet, except the ones that are placed lower in the mountains and linked to 2m repeaters. There is a reason for that, the PAVE PAWS missile defense site site north of Sacramento, that forced prominent high-placed 70cm repeaters to go off-air. On opposite, Los Angeles area has a huge number of 70cm repeaters on air. Quietness of the ether may not be an indication that there is something wrong with the radio.
  5. Pretty much any radio other than Btech-Baofeng would do that. All Part 95/Part 90 commercial radios certainly can be programmed that way. Not sure about Wouxun 805G, but owners would chime in and clarify that.
  6. At the base of the antenna, meaning close to the connector on the antenna? If at the base of the mast, then the choke will not prevent coupling with the mast.
  7. So, cannot pull antenna off from the mast to check the coupling? Too bad. Is there is a chance that the loop on the cable to pull it through the mast is too tight? The ferrite choke should be something like in the following link, installed as close as possible to antenna. https://palomar-engineers.com/ferrite-application-experts-2/Dual-Band-VHF-UHF-Antenna-Feed-line-Choke-J-Pole-Verticals-Hand-Held-Beams-Choose-1-4-1-2-3-4-cable-size-100-500-MHz-p165437793
  8. Most likely you have your coax coupling with aluminum mast. J-poles create significant common-mode current on the outside of the coax. If mast is not metal, you may be able to get away with that. To verify, pull the coax away from the mast and check SWR again. If you see it changed, then this is it: coax coupling with the mast. To rectify add RF choke made of ferrites for UHF frequencies, or change antenna. Off tangent: this forum has strange fascination with Ed Fong's antenna. It's cheap, sure. But it's a kit, that is missing important and expensive part: RF choke. There are better options for the GMRS antenna. The Browning BR-6140 was available for below $40 for long time, but sadly not anymore. It now commands the whopping $50 at AntennaFarm. If you are also into Ham, the dual-band Diamond X50 has acceptable SWR on GMRS, at around 1.7.
  9. After giving it some thought, it may be a valid experiment. HT (or FT-817) is inside the zip log, wrapped with kitchen foil, on the wet sand or swamp ground. Make sure there is absolutely no electrical connection between radio, or cable shield and the foil. MASSIVE choke on the coax, inside the same Faraday cage. Operator 1 is next to the radio pressing PTT through the foil, Operator 2 is measuring field strengths with whatever method available.
  10. Of course, the back connector and the front BNC connector are bolted to the same aluminum body of the FT-817/818. The ground bus inside the radio electrically bonded with body and case in several places. I can only come up with the one sure way to isolate the body of HT or any other radio: put in Faraday cage NOT electrically connected to the body, but providing very low impedance and very short path to the ground. Something along "wrap your HT with kitchen foil, put inside the zip log and bury in the wet sand on the ocean beach". Also, have a very high-impedance RF choke on the coaxial. But how are you going to press PTT and speak/listen? The remote mic cable will radiate better than HT body, it's longer! (look up so called Tiger Tail) And I will repeat, this is the property of the short wavelength. The shorter, the easier for RF to escape through ground buses, connectors, cables, etc. The only solution is to wrap yourself together with your HT and have yourself buried with the radio in the wet sand. You would need a snorkeling pipe. Make sure your will is current and signed by two witnesses. And report the results! I'm genuinely interested.
  11. The FT-817 has exactly the same behavior as HT on VHF and UHF - meaning body being a part of the radiator. It's not a radio problem/feature, it is rather the attribute of the wavelength. On HF the diminutive body of 817 does not contribute anything meaningful to the electromagnetic field, but on UHF the linear dimensions make it very close to 1/4 wavelength, thus it will radiate, and a lot. However, the original post was about low-power transmission, not about how to judge the radiation from the dummy load.
  12. Tough stuff! My past summer troubles on the outskirts of SF Bay Area during the fires, 5 days without the power, is a children camping expedition in the backyard, comparing to your story. Anyway, after reading it, if it was me, I'd focus on better car-to-car-to-home-to-pedestrian system. GMRS gives you an option to run 50W with your family covered by one license. With antennas on the roofs of the vans/SUVs/cars, that's a lot of distance even in flat Florida. If I understand correctly, when hurricane is at full force, the crummy Ham antennas go down much sooner than commercial LMR installations. I would not put much hope into Ham during disaster. And certainly not into the Ham repeaters. I'm aware of ARES, and I saw (listened) to them few times, and my take out of it - they are not here to help the Precious Me, specifically. I'd forget them altogether and focus on what I can control: the reliable comm family system with trained participants. Actually, this is exactly what I did some years ago - we have 40W mobiles in our cars and at home, everybody is trained to use mobiles and HTs (because we use them all the time when outdoors camping, hiking, etc), everybody is aware about Radio-3-3-3 protocol, the quick reference cards are in every car, the buttons and channels are programmed in the same way on mobiles and HTs. And there is a dedicated "home channel" programmed to the same "B" button on mobiles and HTs: the frequency+DPL, and there is also a reserve frequency. And there is a contingency plan. We live in Livermore, and both me and my wife commute to Silicon Valley proper, across the mountain ridge. So, should "the Big One" hit, everybody knows that it would take me 48 hrs MAX to get home on foot. If neither me, nor mom at home after that, the youngsters are on their own.
  13. The answer will depends on what do you want to do with Ham HT. If to talk on repeaters any HT will be good, and if to talk only on UHF repeaters, many of Part 95A radios will tune to 70cm band. If you are into camping-hunting-kayaking and want to talk to your Ham buddies, this is where VX-6R shines being waterproof and sturdy. Any digital activity in your area, DMR or D-Star or Yaesu's System Fusion? If you are interested in any, that narrows down the choice. The Cadillac of Ham HT's (when money no object) Kenwood TH-D74 is discontinued, thanks to fire on the component factory and pandemic. But they will come up with something along the lines of D74 real quick. I have Yaesu FT-1XD, the predecessor of -3DR. Very complicated in operation comparing to foolproof Kenwood TK3170. But smaller and lighter. I've got it because I wanted APRS, this is the feature I use. Looking back and choosing between FT-1XD(-2DR, -3DR) and Kenwood TH-D72(-D74) I would still chose Yaesu because of its smaller and sturdier built and water resistance. On the other hand, Kenwood has packet modem, and can be used for Winlink, while with Yaesu is not that simple at all. And these Yaesu menus are killing me, even though I seem to remember them now without needing the cheat sheet. Choises, choices....
  14. 840 vs 880 vs 8180: also consider software. I understand that software for 840 is DOS, while 880 and 8180 is served by Windows applications. If you are not afraid of dealing with DOS, then fine. 8180 also has a removable head, allowing better installation in tight spaces.
  15. Regarding TK-880, you want "-1" if you want to have Part 95A certification. This radio also tunes to 70cm band. You may also look at TK-8180, they seem to be more available on ebay lately. When I was building out my system years ago, ebay was literally flooded with TK-880 in every possible flavor. Today other choices seem to be more available. The TK-3170 and 3173 may be a radio of choice, depending on who's choosing and why. I have both. They are quite big by modern standards. Lscott covered them already. Radio can work with both Li-Ion and Ni-MH batteries, that are available for a reasonable prices on ebay. Charger that can handle both chemistries is KSC-25.
  16. The -1 -2 and -3 mean alignment in the UHF band. 1: 450-490MHz, 2: 485-512MHz, 3: 400-430MHz. Type -1 is 95A certified. The version V2 and no version, that is often called V1, are the versions of the hardware. For GMRS purposes they are no different.
  17. Make a plan for troubleshooting. It seems that you suspect an antenna, for whatever reason. So, confirm or refute this hypothesis, that the antenna is the trouble. Send a buddy in the car 15 miles away and communicate with him through this antenna and feedline on simplex, bypassing all the wonderful machinery, diplexers and stuff. Make sure you trust the antenna and the feeder. With the result on hand, the next troubleshooting step will become apparent.
  18. If you want to keep repeater private, you may set a different input tone, that it's not so easy to be scanned. Thus, repeater owner can control, to some extent, who can use the repeater. Also, till recently, only the good quality Part 90 and Part 95 radios were able to do split-tones. Using split-tones it is a way to keep people with CCRs off your repeater.
  19. After 2017 rule change FRS and GMRS use same frequencies, except FRS cannot use repeater inputs 467.xxx0. Kids may be clean in the eyes of the law if they use FRS radios. Just for your information...
  20. TK3170 also operates on Ham band. At least on upper portion of it, where repeaters are. I did not do any tests with any measurement equipment. Same thing with the software: it brings a pop-up saying that frequencies are out of range, but still allows to program them.
  21. I think everything is covered (capacitive coupling), but I can add that 1/4 wave antenna works like half of the 1/2 wave dipole, where the other half (other 1/4 wave piece) is an imaginary part created by the reflection from the flat groundplane. So, DC ground is not needed, but the closer the groundplane to the ideal RF ground the better. Capacitive coupling between magnet and metal roof provides low impedance on UHF frequencies, good enough to work as an RF groundplane.
  22. And Ham license is also now $35. Historical move. Ham license, aside of the testing costs, was always free in US, right?
  23. Sooooo-o-o, according to the Table 2 to Paragraph C the new license is $35. And schedule is effective April 19. Do I read it right?
  24. Longer cable will make the electromagnetic field from the cable stronger. The coiling may or may not make it stronger, but will not reduce it on UHF. You need to suppress the common mode current on the outside of the cable shield (this is why quad shield will be no difference). On UHF this suppression is not as trivial as on VHF or HF. The 1/4 wave stubs are often used, but they are very narrow filters. Another approach is to have several ferrite beads (4-7) on the outside of your cable.
  25. https://www.theantennafarm.com/catalog/index.php?main_page=index&cPath=191_192_196_215 But I don't have personal experience with any of them.
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