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axorlov

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Everything posted by axorlov

  1. I don't have one. Judging by photos (post 29), it has two radiating elements with a phasing/loading coil between them. Upper element is probably 1/2 wave. But hard to tell.
  2. It's not just the dummy load that radiates, it's the whole system ht + cable + dummy load. You would need to have a good RF choke on your cable to judge the radiation just from the dummy load.
  3. If no ground plane, the answer is simple: 1/2 wave. 5/8 will work with reduced efficiency, 1/4 will also work but your SWR will be high.
  4. Alternative is to use 1/2 wave antenna, that does not need ground plane. https://www.theantennafarm.com/catalog/index.php?main_page=index&cPath=191_192_196_215
  5. If you think of it from everyone's (other than Ham) perspective, it is very simple. FRS/GMRS sliver is in the middle of UHF business band. Allowing ham equipment will certainly wreak a havoc. Part 90 radios have much tighter spec than Ham radios from yesteryear (and today) and lower power limit too. Allowing 1500W ham radios will make these bubble-pack FRS unusable in densely populated areas. There is a thread here about how 1W baby monitors bring GMRS repeaters to their knees. Pity. Imagine what 100W (or 1500W) Ham radio would do to the same repeater and to adjacent land-mobile installation. The point of FRS and GMRS is to give cheap communication option to every random Joe, not to facilitate just another eight (fifteen) 25Hz channels for Hams. Hams do not need them, there is nobody ever on 446.000, and let's not even start on 220MHz - not funny. But you certainly can use your 'carefully selected' Part 90/95 radios on Ham bands, if you have license.
  6. The reference is for the exhaust tuning of the internal combustion engines. This is not only similar physics behind it (and fallacies) but exactly the same. The same wave theory applied to processes inside exhaust pipes and antenna feeders. The point is to match the impedance and reduce the amplitude of reflected waves to not waste energy on pushing exhaust gases through the pipes, and the current through the feeder line and antenna. Two-stroke engines are especially sensitive to exhaust tuning, because they relay great deal on the wave processes inside the pipes (SWR, if you wish) to ventilate out the wasted gases and fill the combustion chamber with the fresh fuel/air mixture. Four-stroke are less sensitive to exhaust tuning (but still are!) but more sensitive to intake tuning for the very same reasons - wave behavior in the transmission lines (intake and exhaust manifolds and pipes). So, the nature of the phenomena is different, but the physics behind it the same, so are misunderstandings.
  7. Same with me. I enabled all three of my TK-880 for the front panel programming, and I used it, let me remember how many times... oh yeah, never! I do keep a printed reference card in the glovebox, just in case of apocalypse, or when I'm tooooo bored. With the handhelds TK 3170 I did not even bother to enable FPP. Too much trouble.
  8. Not really va the FPP, but rather OST feature - Operator Selected Tone. Kenwood 3170/73 can store up to 40 combinations, they can be split tones too. You'd need to program a button on the HT to chose the tone combination.
  9. Yes, I forgot to mention, the BR-178-S ("S" is for spring at the base, there is a version without the spring too) has a cut table, and you are supposed to cut the whip according to the frequency to fine tune the antenna. I cut according to the table and have SWR 1.7, which I find acceptable. Perfect is the enemy of good. So, in the end, the antenna will have much narrower useful bandwidth than 380-520.
  10. But you still have to work on your Midland or BTech. You need to come up with antenna mount, hook up and route power wires and fuses, place mounting bracket. In the big picture, putting an antenna connector and power connector are small things, comparing to other things. Also, there are plenty of radios with connectors intact. Complexity of used commercial radios does not come from missing connectors - these are easy. Complexity comes from finding programming software and learning to program your radio. This is why I'm sticking to Kenwood - in general they are easier to deal with than Motorolas. And used commercial gear will keep you on air for much longer than BTech (LOL!), It kept some sheriff department or transit bus company on air for 15 years or so, it certainly will hold to GMRS use. And the price should not be ignored, right? Below $100 vs $250 for MTX400. And you are getting superior radio in every aspect.
  11. I use Browning BR-178-S. Works well. I did not compare it with 1/4 wave, but I did compare it with Browning BR-170-S, which is 5/8+1/2. The 170 (longer) is marginally better in flat lands. Both 178 and 170 require ground plane, but I see you have XJ, so you're good.
  12. Memory map: from my experience as a HW and FW developer, that is usually the mapping of the microcontroller's registers to memory addresses, and also the microcontroller's memory too. They can be read-only, read-write and write-only. But I think, somebody who succeeded hacking the installer, already knows that. You certainly can look up serial number, but it is open question if you can change it, i.e. the system will accept the write attempt at the specific address.
  13. Before I drilled my roof for NMO, I pondered 1/2 wave antenna, mounted on fabricated mount that would go under the bolts that hold the hinge of the rear hatch on Durango 2014. Advantages: no need for groundplane, ok to be on the edge of the roof (it's 1/2 wave), no roof drilling. Disadvantages: longer than 1/4 wave antenna. I went with drilled through the roof NMO, but I had something as big as your roof tent, I would consider again. You probably can fabricate something on the back, for the hinge mount, and it probably will be further from the tent (you need to open that hatch somehow, right?) than what's on your photo. Just a thought. Also, in Taipei, the half of the cabbies carry the setup similar to what I just described. Prius or other hatchback with longish (for 70cm) antenna mounted with bracket that's attached under the bolts that hold the hutch strut. I tried to ask, but was met with the blank stare. I do not speak Mandarin, and cabbies probably do not know the details of the radio setup anyway.
  14. Nope, haven't had any experience not in Virginia. North California has a 70cm restriction because of the missile defense site located near Yuba City, Beale AFB. Because of that almost all 70cm Ham repeaters in SF Bay Area and Sacramento either went quiet or go with severely reduced power. We still have our microwave ovens allowed! GMRS is allowed too. In a contrast, Los Angeles area has a thriving fauna of 70cm repeaters, unimpeded.
  15. Yes, knife-edge propagation is why I'm able to watch off-air TV being in the shadow of a mountain ridge.
  16. dxengineering.com has mag mounts with RG-8X cable. Ebay too.
  17. The pair of DLR 1060 is here, and I had a chance to play with them in suburban environment. The setting was simple: Operator1 is riding bicycle around, Operator2 is stationary at the BBQ table at public park. Communications were happening via a pair of TK-3170 and a pair of DLRs. TK-3170 were configured at wide-band full power (4W) with DPL. DLRs are on default setting: Channel 1, no PIN. So, the DLRs did not outshoot Kenwoods, but were not than much far behind. When we lost comms on DLRs, Kenwoods demonstrated a lot of white noise, and while squelch broke reliably and spoken words were 100% discernible, my experience tells me that we would lost comms via Kenwoods in about quarter of mile. Two experiments were performed. Experiment 1: Across the park, quarries and along the river bank with minimal obstacles. Trees are rare and foliage is not dense. Not exactly open field, but close. Comms failed when our line of sight started to go through the suburban subdivision. Distance was 1.75 miles. Experiment 2: Through dense suburban subdivision with 1- and 2-story homes on small lots. Comms failed at approx 0.75 miles. Unfortunately, I was not able to borrow better FRS radios like GXT1000 to make a direct comparison. But DLRs were not much worse than full-power TK-3170s, so they will leave FRS in the dust, especially crappier ones. DLR is seriously smaller and lighter than old brick TK-3170. It can sit in the front pocket of shorts and does not impede bicycle riding, while there is no way I can stuff 3170 into the pocket, it must be on the belt. Next test is in the mountains, but it's not going to happen soon because of some time constrains in the coming month. Besides, Operator2, colleague and friend, borrowed DLRs for their family outing over the weekend.
  18. Simplex repeater appears not to be allowed. There are words about "store and forward" not being allowed in all Part 95. However, I actually have and I use Argent Data simplex repeater. I only use it in the mountains, never in the urban area. The ADS-SR1 can be configured in a smart way: it will not automatically blurt out anything it hears. It will record and sit quietly, until it hears DTMF "0", only then it repeats the last recorded message. So usage mode is this: we talk on simplex with HTs, while ADS-SR1 quietly sits in the car, parked in good spot (or any available spot), connected to 40W TK-880 and efficient antenna. It does not repeat anything. Then I find myself far from the others where HTs are not picking signal. I call and wait for sufficient time to answer (say 1 minute), and then I send DTMF "0". Simplex repeater hears it and shouts out the last call (supposedly mine) with all 40W out of efficient antenna. I hear it myself, I know that now it reached recipients, most likely. This scheme works like a charm. You do not pollute the waves until really needed.
  19. Hamexam.org, go there, start taking practice tests. Do not order the book just yet, because there are resources to help. See how you do with the practice tests. Btw, creating an account is not needed, but if do create an account, it'll keep your statistics and point to areas where to concentrate studies for the improvement. Once you are confident that you pass, go ahead, schedule the appointment or whatever it takes these troubled days.
  20. If your background is in natural sciences or crafts, the test preparation will be easy. On the other hand, if you are more into philology, literature (especially english romantics of 18th century), art in general - the preparation could take like maybe the whole 4 hours! There are helping resources on the internet. hamexam.org is one, there are plenty of others.
  21. VHF and UHF and shorter frequencies are mostly line of sight. The HF (aka shortwave) is reflected from ionosphere and gives you a global reach. VHF and UHF sometimes are too reflected from atmospheric layers (tunneling) and from ionosphere (E-layer reflections), but this type of propagation is accidental, not reliable at all. VHF and UHF can be reflected and diffracted from and by any sort of things - meteors, airplanes, buildings, rocky canyons. This is how you get non- line of site communications on V- and UHF. Hams do these modes for fun, you can look up airplane scattering. There is also a ground wave - when RF truly goes around the the curvature of this miserable planet, over the mountains and oceans. But the shorter the the wavelength, the less pronounced the effect. It's pretty much nonexistent on 40m and shorter. Best examples of ground wave are MW and LW radio broadcasts.
  22. 4W vs 5W - negligible difference if any at all. Performance difference will come out of receiver and transmitter details, that I can't comment on because did not see schematics, tests, etc. Antenna is removable. Actually, they are interchangeable between 3170 and 3180. There are two types I own and I prefer longer antenna (KRA-27) on my 3170. And 3170 is not that much smaller than 3180. Maybe inch and a half shorter. If you already have a setup for 3180, cables and other accessories, it's not worth to move to 3170 in my opinion. Being it fat bulky in-your-face radio may be a positive. To one crowd you may look like a cop, to another like a vigilante militiaman. Exploit possibilities!
  23. You can install KPG-101D without the radio to play with it, see what's available. The software is available on the internet with some searching. Here we are discussing possible button assignment on TK-3170: https://forums.mygmrs.com/topic/1328-kenwood-tk-880h-1/page-2?do=findComment&comment=14890
  24. I have 3173 and 3170. For the purpose of GMRS these two are identical, and both are programmed with KPG-101D. There is indeed an option to set CTCSS or DCS separatley for receive and transmit, so called "split tones". On the Zone/Channel screen these columns are called QT/DQT Dec (receiving tone) and QT/DQT Enc (transmitting tone). You can set tones here. Another option is to use OST feature (operator selected tone) where you can program 40 tone combinations, and program a button on the radio to invoke the OST menu. This option is in Menu -> Edit -> Optional Features -> Conventional.
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