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Thread: HELP! -Antenna works only when touching?

  1. #1

    Default HELP! -Antenna works only when touching?

    I hope someone can help me. I have a slightly older 900MHz 200mW video Tx for use in mast photography, but it ONLY sends a good signal if I physically touch the antenna with my hand. I am aware this is bad for circuitry and can cause overheating, and obviously can't "touch the antenna" when aloft.

    What do I need to do to make this little transmitter send a clear picture? Should I ground the antenna to a neighboring piece of chasis on my camera rig or what? I am really stuck.

    All suggestions and clues appreciated!

  2. #2
    Join Date
    May 2009
    Location
    Chico CA
    Posts
    195

    Default

    I had a transmitter like that about twenty years ago. It was very expensive and had to use YOU as the antenna to work properly. Either find a suitable ground for the antenna or purchase a new transmitter. I'd go with a new one. There pretty cheap and work great!

  3. #3

    Default

    The transmitter is not THAT old. In fact, it looks exactly like the 500mW model offered now. The transmitter DID work before, but now ONLY when touched, so something has come lose. What could it be????

    As far as finding a suitable ground or finding what went wrong, basically how do I proceed to do that?

    Thanks- Phil

  4. #4
    Join Date
    Oct 2009
    Location
    New Hampshire, USA
    Posts
    504

    Default

    Is it a plastic/rubber coated rubber duckie antenna, modifed monopole, bare copper wire, or RV vee antenna?

    Really need more info other than "when I touch..."

    However....

    When you touch, are you physically moving the antenna in reference to the TXR? i.e. bending it ever so slightly? If so, the connection in the TXR could have broken loose or the antenna internally is broken. Swap out with another known good antenna and see if it repeats, if so, then it's internal to the TXR.
    Pull the cover's off the TXR and look at where the SMA antenna connector passes thru the case, look for broken solder joints or components while applying lateral pressure to antenna. Pay particular attention to the center conductor of the SMA connector.

    Kriss KA1GJU



    Quote Originally Posted by AeriallensSC View Post
    The transmitter is not THAT old. In fact, it looks exactly like the 500mW model offered now. The transmitter DID work before, but now ONLY when touched, so something has come lose. What could it be????

    As far as finding a suitable ground or finding what went wrong, basically how do I proceed to do that?

    Thanks- Phil

  5. #5

    Default

    Thanks, Captnkliegle and mspenser. It is now solved.

    What I was using was a rubberized, short antenna for 2.4GHz instead of the almost identical-appearing one for this 900MHz device. The real difference was in their internal center pins and the small nylon insulator around the pin, where it screws onto the male transmitter post. The proper one had a slightly shorter pin and insulator.

    All is well now. Lesson learned: do not co-mingle stuff that looks identical but in fact is not.



    Thanks again, guys!
    Phil
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