Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

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

  1. Apr 21, 2011 #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: https://www.amazon.com/Motorola-MH2...1_fkmr0_1?ie=UTF8&qid=1303428944&sr=8-1-fkmr0
    Last edited by a moderator: Apr 25, 2017
  2. jcsd
  3. Apr 21, 2011 #2


    User Avatar
    Science Advisor
    Gold Member

    You might want to look into Amateur Radio. You can legally do this as this club has:

    http://www.arhab.org/" [Broken]
    Last edited by a moderator: May 5, 2017
  4. Apr 21, 2011 #3
    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. Apr 21, 2011 #4
    Before you get too far along with your plans you should review the FCC Rules for GMRS radios. http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&sid=604cc032b6ac0ad96ca79eab6219ca27&rgn=div5&view=text&node=47: [Broken]

    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).
    Last edited by a moderator: May 5, 2017
  6. Apr 21, 2011 #5
    Last edited by a moderator: Apr 25, 2017
  7. Apr 21, 2011 #6
    Have a read through this - My school achieved a ridiculous range, I'm pretty sure it details radio comms somewhere there: http://www.hexoc.com/pages/apex/apex-ii.php

    Edit: Here is the technical document specifying data transmissions: http://balloon.hexoc.com/media/apextech.pdf [Broken]
    Last edited by a moderator: May 5, 2017
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: Is it possible to build a mobile linear amp for a walkie talkie?
  1. Build a Linear Motor? (Replies: 6)