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OldRadioGuy

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Everything posted by OldRadioGuy

  1. There is one situation where PL tones work pretty much like people want them to. If I'm on my 2 acres talking with my family on one PL tone and another family a mile down the road is on their 2 acres using a different PL tone on the same channel it will behave pretty much like our two families are on different channels. The signals within our family groups are strong enough to overwhelm the signals from the other family and the PL tones block us from hearing each other. Back when businesses used GMRS/FRS it would work OK. The gas station and hardware store down the street could have their own conversations without getting all mixed up. Of course any listener who turns off their privacy tones will hear everything said on that channel. So it is only a voluntary privacy. I always leave the tones off because I want to know if the channel is being used... but we don't live in a busy area. I suppose turning on XMIT tones only might give you some privacy while allowing you to hear other traffic on the channel. Vince
  2. I had a good case of ducting once back in Nov. of 1986. I had just moved to my new house in Greenfield (southern NH) and put on the portable TV to test the signal. I was relieved that I was still getting the Boston MA and Manchester NH channels OK - but there was another rock solid channel that I was not familiar with. I watched for a while and it turned out the be Burlington, VT which was shocking. That's 160 road miles away with mountains in between. It just didn't seem possible but there it was - rock solid. I had only moved about 20 miles further up from my old place in Milford NH. I'd never heard of anyone getting Burlington TV around southern NH. It was not a TV repeater channel either. It was the Burlington channel direct. It was probably 9 or 10pm at night. The next morning I tried it again and it was nowhere to be found. Tried it a dozen more times and nothing but blank screen. It was just a case of ducting that came and went. Vince
  3. Yep, Mbrun is right, but you may need a lot more than 100'. Try getting something metal (vehicle, metal shed) between you and the nearby transmitting radio. You may also try using lower xmit power if that's an option on your radio. It's a common problem. Vince
  4. In hilly places like VT repeaters are necessary to get much range. So HAM is going to get you much better service than GMRS unless you happen to be in an area with a GMRS repeater..... which is unlikely. See repeaterbook.com for listings of HAM repeaters in your areas of interest. Also, with HAM you have other freq. choices that can be very helpful. VT is very wooded and snow gets on the trees which tends to eat up higher frequencies. So 2 meters or 144 MHz can be a better alternative. GMRS is great for reaching your fishing buddies or other nearby but longer ranges are very dependent on repeaters. I have GMRS because my wife and fishing buddies can't use HAM radio. So it has its place. I lived in NH for some of my HAM years and (30 years ago) repeaters were quite good. I was often able to reach people with 5W and a mag mount. There were "ham-fests" in VT and more hams than you'd think. I expect that there are still some HAM clubs around VT. This is the best way to get started. Today the issue can be finding a live person on the repeater. But if something was "going on" I'm sure there would be lots of hams on there. Vince
  5. Transmitting with no load is a very different thing depending on the length of coax connected to the radio. An open circuit plus 1/4 wavelength of coax equals a short circuit. Any odd number of 1/4 wavelengths will look like a short. So the load seen by the transmitter can vary a great deal. Some lengths could possibly make the transmitter unstable causing it to oscillate at some other frequency. But this is somewhat less likely in newer radios where device parasitics are much lower today. But it's still possible. Note: 1/4 wave at 460MHz is about 5 inches. Remember that wavelengths are shorter in coax than in free air. You have to multiply by the velocity factor for the particular coax.... usually around 65-75%. When there is nothing connected to an HT it's likely to look like an open circuit since the transmitter circuits are likely very close to the connector. So this would be one of the safer no-load conditions. I suppose the worst case would be an apparent short circuit that may cause overcurrent but today's transistors are much more rugged than the ones of the 1970's. And, since your radio probably uses a switching power converter it's unlikely to provide enough current to cause any damage. Of course we are talking about hand held radios here. I would not key a transmitter intentionally into an unknown load but I would not worry about doing it unintentionally for a short period of time. It certainly can happen for a variety of reasons, like forgetting to replace the antenna after a car wash or something. Most legitimate radio designs would handle this fine. Designers are aware that this happens.
  6. Stainless steel is very compatible with brass and nickel plating. (Of course gold is inert so no worries there.) So you'd be fine using stainless. Stainless gets along pretty well with aluminum too if there's any of that involved.
  7. As the others have said it makes a huge difference. The biggest problem can be the strain on the connector from the heavier cable. It's often good to put a right angle connector (or two) at the radio. Ham Radio Outlet sells "pigtail" adapters with a short length of thin, flexible coax. Another idea is to use a speaker mic so you are not trying to drag that antenna cable around. Powerwerx has a good speaker mic for cheap that works on KG805's. Pasternack sells custom cables if you want to make your own custom flexible adapter cable. RG316 or RG174 are nice thin coax cables for a short length. Vince
  8. I can see that you are just a troll so I'll move on. The "maths" speak for themselves.
  9. For those of you who don't believe it... let's do the 1/4 wavelength calculation. 300/(462MHz x 4) = 162.3mm low channels 300/(467MHz x 4) = 160.6mm repeater channels (162.3-160.6)/162.3 x 100 = 1.04% Looks like the math is linear enough. Vince
  10. Antennas are never a full wavelength so N/A. Most simple vertical antennas are 1/4 wavelength. And it's spelled HERTZ not hurts. Vince
  11. 5/462 MHz x 100 = 1% (rounded off) The difference between the "lower channels" and the repeater channels is 5MHz. Vince
  12. I have the "surveillance" style headset (for Wouxun 805G) from Buytwowayradios and the vox function does not work very well. We did not fiddle with it too much but never really got it to work the way we'd like. I'd like to try our speaker mics on vox and see if that works any better. Our speaker mics are from Powerwerx and they seem very nice for the low price. You can clip it on your collar or hang it on a neck cord. Vince
  13. The frequency difference we are talking about here is 1%. So, would you want to shorten the antenna 1% ???? (rhetorical question, of course you wouldn't) I just wonder if something else is going on. Unless it's a very short antenna with a very narrowband match. It just doesn't make sense. Maybe the meter is the problem. CAn you try a different meter and cables? Vince
  14. Why don't you get a Ham license? They have a lot more repeaters in most areas. I have both and they both have their place. Vince
  15. Maybe I missed it but I don't think anybody mentioned SSB CB radio. SSB is 4x(?) more efficient than AM and also uses much less bandwidth so lower noise - if the filters are done right. It is still a form of amplitude modulation so there is more static than FM. But AM fades more gracefully than FM which tends to be "all or nothing". Sometimes on AM you can make out a very weak signal that would not be captured by FM. The longer wavelength will handle terrain better but the antenna also needs to be much longer. It's pretty hard to put a number on all the differences. Vince
  16. It would not make any sense at all to try and convert it. 465MHz/28MHz is16.6x higher frequency. Even if you cut it down short there may be matching components that will filter out the 465MHz. 1/4 wave at 465MHz is only about 6-1/4 inches. Vince
  17. All of my 70cm ham antennas work fine on my GMRS and have and SWR well under 2:1. Vince
  18. I should add that my two spare batteries were still fully charged after sitting the same length of time- but not on a radio. Both of my radios were stone dead. Having worked in this stuff, some designers just don't worry about such things. They put the processor in sleep mode and figure that's good enough. They don't want to bother with circuits that wait for the switcher to reach voltage and reboot the processor whenever the power is turned on. It certainly can be done but they just don't bother. They probably imagined that people would store the radios in the charger base when not in use. But not everyone does. At my last job it took about 2 full days of arguing to get a lazy project engineer to change the design so the batteries were not drained while being stored. And they were not removable batteries!!! And it was a product that is often stored for long periods between use. The fix cost like 20 cents. But this is how some engineers think. I have inserted paper tabs in my 805G radios so I can leave the packs attached but not connected. This way I don't have to carry the batts separately. When I want to use the radio I'll just release the pack and remove the paper. Seems to work well. Vince
  19. Your radio head should be fine right ext to the antenna. They are made for this. Some ferrites on the power lines wouldn't hurt but no big deal. Of course you want a decent ground up there. You may notice a greater improvement on RX rather than TX. Your coax loss adds directly to your noise figure of your RX. So you may see a noticeable improvement. While 30' of coax is acceptable in most cases I think eliminating it will help on weak signals. Modern radios have very low noise figures so it's easy to double it with some coax loss. I think it's good to keep it to a minimum. Vince
  20. I just discovered that my 805G's drain the batteries dead while sitting on the shelf. (They were not sitting in the charger bases or connected to anything.) They drain the batteries right down to 6.2V which is where the battery safety circuits shut them off. This is not good for the batteries. It's rather disappointing to find a flaw like this in an otherwise good radio. So.... if you have these radios remove the batteries when you store them for more than a day or two. My Cobra radios do not have this problem and that's good because the batteries are not easily removed. At least the Wouxun batts come off very easily. It looks like you could easily insert a strip of sandwich bag or paper between the battery and the radio. So you could have the battery installed but not bleeding to death while stored. Just yank the plastic strip when you are ready to use the radio. I think I'll try that. When I was working as an engineer we had engineers who just put the processor to sleep when you "turn off" a device. It's not truly turned OFF. It was mostly so they wouldn't have to do a reboot every time you power up. But storage would kill the batteries dead. I always made my stuff shut off below 5uA which is like a wrist watch. Most tablets and cell phones are pretty good. A short press puts it in standby but a longer press powers it OFF for storage. So you can have it both ways. Vince
  21. My point mostly was that these radios may not be tested in production. So you may get a good one or you may get one that under-performs or even interferes with other services. Testing is expensive and tossing the ones that don't pass is even more expensive. So they just build and ship. Maybe they do a functional test or something very basic. Lots of cheap Chinese stuff tends to be this way. Harbor Freight, for example, has some great stuff for cheap, but sometimes you have to pick through the stock to make sure you get a good one. Quality is inconsistent. I think Wouxun is a level above this. I think they do test their radios. One reason is that Ham Radio Outlet sells them but will not sell Baofeng. They test some samples to make sure they are legal and basically in spec. before deciding to carry them. Of course the major brands Kenwood, icom, Yaesu, Alinco, are reliably good. And even if you see a Yeasu that appears to be made by somebody like Baofeng it isn't necessarily the same. They production test everything and they don't sell what doesn't pass. So you're getting a hand picked Chinese radio. The radio tester guy from our club does use the Baofeng. So it's a serviceable radio. He just understands the limitations. Vince
  22. A guy in our ham club was a project engineer on the hp 8920A transceiver tester. He gave us a presentation on radio testing and one of the examples he used was a Chinese dual band HT. I think it was the Baofeng UV5. It met most of the specs very respectably but one or two of them were WAY off the published numbers..... like 5x worse. It still met the legal requirements but not the published specs. I believe it was sensitivity that it failed. He only tested one sample so who knows what 20 others would do. His ancient Kenwood radio passed every published spec with margin. Overall he considered the Baofeng to be a decent radio but certainly not passing their own published specs. So some of the Chinese radio thing may be hit-miss quality control. I do like my Wouxun 805G radios and they seem to perform well but I can't prove it. For recreational use they are fine. These videos are fun and show that the radios are rugged but there may be more to the story. Making a contact shows that it's functions but nothing more. I would be curious to see what my Wouxuns would do on the 8920 tester. Vince
  23. You would think in areas prone to strong hurricanes that they would have better contingencies. And you wouldn't think it would be very good PR to let the Animal Channimal portray them as having zero comms and nav. backup. But they showed these guys asking directions from people on the flooded streets. They made the point several times that all radio communication in that area was down. Incredible! Vince
  24. I was watching the Louisiana game wardens show which covered their participation in the recent hurricane rescues. The wardens had absolutely no comms or navigation because the repeaters and wireless internet were all down. Without the repeater their radios are completely useless and they apparently use their phones with online maps for navigation. They didn't even download offline maps. And these guys are outdoorsmen? I was absolutely amazed that they would not have a Garmin GPS and/or some FRS GMRS radios. They could have had a portable repeater or even a "human repeater" stationed somewhere and had at least limited coverage of an area. Or what about marine VHF? Maybe they would tell us that GMRS is not secure (private) and therefore could not be used. They could use codes for sensitive situations. They used to do this all the time when police comms were easily monitored. They kept making a point of how difficult it was to work with absolutely no comms or nav - which made me scream at the TV ? Apparently they don't have amateur radio ARES/RACES groups there either??? Maybe it was just the "animal channimal" pumping up the drama. Would they do that?? ? Vince
  25. I depends on the matching network (if any) on your GMRS antenna. If it has a matching network and it's a high pass type design it will attenuate the lower freq signal. I think many GMRS antennas do not require a matching network so not super likely that there is a high pass network in the bargain. I have tested a few dual band 2M/70cm antennas on my GMRS radio and SWR is just fine. Remember 465 MHz is only 8% higher than 430 MHz. That's not a big deal. Vince
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