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Radio setup for SAR

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

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  1. KM4SPU

    KM4SPU Ham Member QRZ Page

    KM4SPU here. I got my technician license a few years ago and haven't done much with it outside of hitting a few HAM repeaters. I am a search and rescue volunteer and most of my radio use is hand-held out in the woods on SAR missions; usually on simplex. I am very often closer to my truck than I am to base and often have a hard time reaching base with my 8W (Baofeng BF-F8HP) handheld. Since my handheld can monitor dual band, what I am thinking about doing is turning my truck into a repeater where I transmit on a different freq and the my mobile radio re-transmits my signal boosted on the SAR frequency.

    I am have never dealt with mobile radios or antennae so I am a bit of a newb, so the solution needs to be simple (ie: buy and install, I'm not going to build anything). In addition to the amateur bands, the mobile radio would need to tx and rx between 151.1375-159.4725 and 453.2125-458.7125.

    I am looking for recommendations of radio and antennae models and setup... and if my plan makes sense.
  2. KM4DYX

    KM4DYX XML Subscriber QRZ Page

    Welcome aboard,

    I think your plan makes sense. I'd even consider going one better and looking into lightweight portable masts to mount your temporary repeater antenna up even higher. Sorry, no specific reccos, but I encourage you to keep at it.

  3. KL7KN

    KL7KN Ham Member QRZ Page

    Unless you put a duplexer in the truck, you are looking at cross band repeat. AFAIK, no can do per current FCC rules.

    You might want to consider a hign gain antenna instead.
    K4AGO and KC8VWM like this.
  4. KM4SPU

    KM4SPU Ham Member QRZ Page

    My hand-held radio has a high gain antennae. When I started my research, I found a video on youtube that talked about a cross-band repeater with the Kenwood TM VT71A, but that radio doesn't operate on those freqs. I have thought about a portable mast. I am often driving on fire roads with low clearance, so it would have to be I could setup and take down very quickly (less than a minute).
  5. N1BCG

    N1BCG Ham Member QRZ Page

    How is your rescue organization handling other volunteer communication? Coordination and integration are critical to successful SAR missions. Also, whatever radio you use to transmit outside the amateur bands will have to be FCC type accepted for those frequencies and meet stringent modulation and frequency standards.
    KA0HCP likes this.
  6. KC8VWM

    KC8VWM Ham Member QRZ Page

    Unfortunately, you can't cross band repeat between two different radio services.

    It's even sketchy to use a mobile radio for "dual use" in both the amateur radio band and on a Part 90 radio service at the same time.

    This is because a Part 90 radio is only certified to be used on Part 90 radio frequencies and nothing else.

    So you can use it on either the amateur radio band or on the Part 90 radio band, but not simultaneously on both radio services at the same time.

    It's not a technical equipment issue but rather it presents a regulatory legal compliance issue for the SAR organization if you do this.

    I suspect any FCC notices and fines can negatively impact the limited operating budget and reputation of the organization, so you're going to want to ensure everything is done in legal compliance with all FCC rules.
    KY5U, KU4X, KA4DPO and 5 others like this.
  7. AG6QR

    AG6QR Subscriber QRZ Page

    You can legally do cross-band repeat between amateur UHF and amateur VHF bands. There are rules to follow, and getting each transmitter to properly ID on each band can be tricky.

    What is not possible under current rules is cross-band between the amateur service and any other service.

    I agree with those who suggest stepping back and coordinating with the entire SAR organization on a coherent communication plan. Otherwise you'll end up with multiple isolated services and bands, with no good intercommunication.
    KU4X and KA4DPO like this.
  8. W0PV

    W0PV Ham Member QRZ Page

    Consider simply carrying a small portable higher gain directional antenna and coax pigtail, such as those offered by Arrow or Elk, or easily home-brewed.

    That would potentially be as much or more usable gain then omni QRO back in the truck may provide, while also being less complicated hence more reliable then any repeating.

    It may not solve all situations with obstruction or terrain blocking the path, but it also enables the flexibility to attempt reflecting or refracting signals indirectly around them too.

    The beam can be tuned to be optimum at whatever SAR frequency required and quick-release broken down to fit into an easier to carry pack until needed.

    73, John, WØPV

    Last edited: Nov 9, 2018
    KA0HCP likes this.
  9. KA4DPO

    KA4DPO Platinum Subscriber Platinum Subscriber QRZ Page

    You will need two separate radios to do what you described as I am not aware of any single piece of equipment that will transmit and receive on the frequencies you want without some modification. Also, there is a legal issue that has been mentioned by a few others that you really can't get around without using two or more separate radios in your vehicle.

    Frankly, I am not even sure about using the Baofeng to transmit on commercial and amateur frequencies but perhaps someone knows more about this part than I do.

    I did set up a cross band repeater many years ago that had input on 144.580, and output on 446.500. I only did it for a short time more out of pure curiosity than any real necessity. I set it up in my car and was able to use my handheld through the link in my car up to a couple of miles away with good results. I only used it for about a week because I didn't like the idea of tying up simplex frequencies. But it is perfectly legal as long as you identify properly.
  10. N5PAR

    N5PAR Ham Member QRZ Page

    Setting up a cross band repeater on the allotted amateur VHF/UHF frequencies is not that big of a deal. The Kenwood TM VT71A or the Yaesu FT 8900R will both work well with a Baofeng or any other dual band HT. Of the two I’d go with the Kenwood. I’ve worked many special events using cross band repeat. The thing you have to look out for is running down the battery in your vehicle. At 50 watts and considering the repeater radio transmits what you and the control operator says it doesn’t take long to kill the battery. A lot of amateurs use a separate battery.

    As others have said I don’t think cross banding from amateur frequencies to other services frequencies is illegal. Plus the Kenwood and Yaesu radio won’t work out of the amateur VHF/UHF frequencies.

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