Radio setup for SAR

Discussion in 'Ham Radio Discussions' started by KM4SPU, Nov 9, 2018.

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  1. W0PV

    W0PV Ham Member QRZ Page

    Here is another account (I won't copy the text) of another far more complex SAR mission in very demanding terrain in New Mexico, which included involvement of CAP, utilizing SAR, HAM, and FRS radios, and relay techniques. The ARRL Letters are full of such stories throughout the past years. Just Google ARRL ARES "SAR".
     
  2. KM4SPU

    KM4SPU Ham Member QRZ Page

    Hey! I read that blog a few days ago!

    It is hard to choose between the Super Stick II 160 MHZ and 150 MHZ. One is tuned at 150 MHZ being the band center, the antenna will perform between 145-155 MHz, whereas the other is tuned at 160 MHz being the band center, the antenna will perform between 155 - 165 MHz. We opperate 151-159 MHZ.
    [/QUOTE]

    Have no idea what any of that meant. Got a picture?


    There are 95 sherrif's offices. We never know which county we are going to until we get paged. Please stop suggesting I fix base. I have no control over how they setup base. I arrive, they tell me what frequency we are using that day, and I go out.

    You guys have given me a lot of good info, and I will upgrade my antenna, which should help some. But, so far the common suggestions have been fix base, recruit knowledgeable HAMs across the state, and deploy mobile repeaters, but nothing about getting a radio for my truck. I don't know a good mobile radio from a bad one. The one thing I asked for and still have not received is a decent mobile radio that can do a cross-band repeat in the from the 453-459 MHZ to the 150-160 MHZ range.
     
  3. KV6O

    KV6O Ham Member QRZ Page

    OK, but your commo problems belong there, not on QRZ. You were/are exploring some things that not legal, and could spell trouble for those holding the licenses.
     
  4. W8LPN

    W8LPN Ham Member QRZ Page

    There are 95 sherrif's offices. We never know which county we are going to until we get paged. Please stop suggesting I fix base. I have no control over how they setup base. I arrive, they tell me what frequency we are using that day, and I go out.

    You guys have given me a lot of good info, and I will upgrade my antenna, which should help some. But, so far the common suggestions have been fix base, recruit knowledgeable HAMs across the state, and deploy mobile repeaters, but nothing about getting a radio for my truck. I don't know a good mobile radio from a bad one. The one thing I asked for and still have not received is a decent mobile radio that can do a cross-band repeat in the from the 453-459 MHZ to the 150-160 MHZ range.



    Ok I will give you this but again crossbanding in public service frequencies may not be legal but the anytone UV 5888 is a dual band mobile that will operate out of ham band. Now again do this at your own risk as this may not be legal. But aside from the legalities this is a decent mobile radio capable of Xband repeat. VHF 50 watts UHF 40 watts. Now if you go this route make sure you have a decent antenna on the vehicle or your transmission will not be optimal. Either a good dual band antenna or a VHF and a UHF antenna with a duplexer (not the kind for a repeater) this will allow you to have both antennas running at the same time from the radio. Hope this helps.

    But again legality is a whole other ball game. You have been warned above by several, so if you choose to do this it is at your own risk. I do understand your issues though
     
  5. KA0HCP

    KA0HCP XML Subscriber QRZ Page

    I think you already have your answer.

    I was involved in multi-agency SAR for years as an IC, and I strongly discourage you from using ham grade equipment on public service bands. It is not legal. This was never allowed when I was active at any SAR activity. If you want to play in the big leagues, pony up the money and buy commercial grade equipment.

    If you want longer range from an HT, get a variety of gain antennas. It is simple to build collapsible two or three element yagis or quads. Look up "Cheap Yagi". Scale the dimension by the appropriate percentage for the public service frequency. Another excellent project is in QST "The Repeater Eater", 2-El quad. Put a counterpoise wire on your HT base. Buy the telescoping whip from MFJ. Use a painter's pole as a walking stick/antenna mast. Carry a roll up J-Pole made from twinlead or ladder line.
     
    Last edited: Nov 13, 2018
    W0PV likes this.
  6. W0PV

    W0PV Ham Member QRZ Page

    Gottcha first time. Won't see that from me anymore. BUT I do still suggest just trying to connect the people who manage SAR base stuff with VA ARES management, and/or vice-versa. Perhaps just an email or two explaining the desire to improve base-to-HT coverage on field deployments and asking if ARES would assist VA SAR in such matters. Technical design, maintenance, training, base operators, integration with existing Amateur Radio resources in VA (repeaters, etc).

    Choose the lower freq range, 145-155, because that is the range of longer wavelength, so if (doubtful) it really needed to be tweaked for above, ie, 155-159 Mhz, all that would be necessary is to not fully extend the last telescoping section by an inch or two.

    Better, here is a SAR group with a product, ironically from your soulmates in New Zealand! (who are also Hams! ;)) Here is a large photo and a video link below.

    Unfortunately, that is not mass produced. But it conveys the basic design. It looks to me like a VHF dipole, the top half element being of very flexible material, ie, tape measure-like, and the bottom being just a plastic tube with the other half element, which could just be exposed dangling trailing wire too, but in this case it provides a sturdy support.

    Here is another blog about making such an antenna out of tape-measure materials. Very rough home-brew, but conveys the idea. Note the photo at the bottom appears to be of an END-FED HALF WAVE, which electronically is not quite the same, but could work fine too.

    The vertical element, or tape, seen, is approx 36 inches, a full VHF half wavelength. Feeding it from the end requires a special impedance matching network which is probably inside that little square plastic box. However, look close and note the two black cable-wires running out each side of that box and dangling out the bottom. Those are counter-poises which improve the efficiency of the antenna.

    What I initially suggested, and appears to be with the Kiwi SAR groups antenna, is a CENTER-FED half-wave. The coax can be seen running to the midpoint just below the whip. That does not require any special matching for common 52 ohm coax, so is simpler. And only the top half, ~ 18.5", is sticking up, and, for a smaller pack, the bottom 18.5 inches can just be a wire dangling like seen in the photo.

    Go hang out at a club meeting some time and enlist a helpful crafty hands-on Ham to help you make one. :)

     
    Last edited: Nov 13, 2018
  7. KA0USE

    KA0USE Ham Member QRZ Page


    i have a cousin involved with sar in pensacola. you might contact him.

    jwboldizsar@gmail.com

    his call: kc4znx
     
  8. W0PV

    W0PV Ham Member QRZ Page

    FYI @KM4SPU - I was curious what material was used for the super flexible whip seen in the SARtrack video. I believe it to be NITINOL, aka nickle-titanium alloy.

    That's the same stuff from which super-flex break-resistant eye glass frames are made. On Google there are reasonably priced suppliers of raw wire & rod for home-brewing.

    There are also several manufactures of antennas using it, primarily for mobile, field-tactical and back-pack HT / portable comms applications. Check out the reasonably priced ready-made HT whips from Signal Stuff called Super-elastic Signal Sticks. There are other vendors too; I googled nitinol whip antenna.

    Those are probably more durable then the telescopic tube spring based Smiley Super Stick II (these guys gotta find different names :eek:) and with similar performance.

    Since they are hand-made by Hams, I bet if asked Signal Stuff would even custom tune whips for the slightly shorter SAR band. The whip would snap right on the HT in place of the rubber-duck even on the shoulder mount.

    Or better, function as the top half of a back-pack dipole (further away from body absorption losses) mounted atop a similar length small PVC tube for support (perhaps just tie-wraps). Then insert a same length wire into the tube and connected to the coax shield as the other side of the dipole.
     
  9. KM4SPU

    KM4SPU Ham Member QRZ Page

    update:

    I got a telescoping antennae and at first I was very pleased in the performance. I tested it home both inside and outside both with the telescope down and extended. I was able to hit amateur repeater and talk crystal clear with folks 60 miles away.

    [​IMG]

    [​IMG]

    Yesterday I finally was able to field test it. Antennae was mounted on my back hydro harness and was zip tied to the MOLLE loop. In the down position it stuck up about shoulder high. In the parking lot I was able to get better reception from the instructors positioned around the park then anyone else. ...THEN I WENT IN THE WOODs. Literally 5 minutes in, I ducked under a branch, the thing snagged and bent in half. So the telescoping antennae was a FAIL and now I will have to try a flexible whip.

    [​IMG]
     
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  10. N1BCG

    N1BCG Ham Member QRZ Page

    A moot point now, but most telescoping whips can only be used fully extended unless they're marked for different frequencies/bands and then you need to set the length closely.

    Glad you're still pursuing this!
     

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