Is it possible to build a mobile linear amp for a walkie talkie?

  1. So, my goal is to be able to take two walkie talkies and put one of them on a near space balloon and have a microcontroller send data through the walkie talkie on the balloon down to the one on earth. I'm not sure it would reach all the way back to earth so I thought of putting a small linear amplifier on the balloon walkie talkie to increase the range. But I have no idea how to build one that would work with a walkie talkie. Any ideas on how I could build one?

    Here is the walkie talkies incase it helps:
  2. jcsd
  3. dlgoff

    dlgoff 3,147
    Science Advisor
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    2014 Award

  4. Instead, I'd optimize the antenna situation. Having line-of-site communications is a great advantage, but you'll likely have all manner of tossing and rotation. Thus, I'd be tempted to attempt circular polarization.
    On the ground, a quad helix would give you considerable gain without becoming a pencil beam. From what I've read, they're fairly simple to build and can feed the 50 ohms or so that you'll likely need. You might look under "wi fi quad helix" for ideas.
    Oh yes, don't forget to insulate it. The top of the world can be a chilly place.

    - Mike
  5. Before you get too far along with your plans you should review the FCC Rules for GMRS radios.

    Here are some excerpts:
    This means that if the balloon drifts over Canada or Mexico, or any other country, you must stop transmitting and that means having a means of turning off the balloon transmitter.

    This means that the meaning of your transmissions must be easily understandable to anyone listening on an ordinary receiver. The FCC wants to be sure your transmission is not being used for any illegal activity. You can't just send data.

    dlgoff is correct, ham radio is your best bet and it's not that hard to get a license (even I have one).
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