Keychain QRP, the worlds smallest HF Ham Radio Transmitter!

Discussion in 'Ham Made Gear' started by KH2SR, Jan 22, 2017.

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  1. K4KKQ

    K4KKQ Ham Member QRZ Page

    Really Cool.
    Imagine an old timer like me, at the Ham Club Meeting, placing his KeyChainQRPrig on the table top, and tapping away,
    ... using his Handi-Talkie to listen to the band, hearing his 14.318 CW signal !
    ... Great way to start a conversation !
    KH2SR and KJ6SZQ like this.
  2. W7UUU

    W7UUU QRZ Lifetime Member #133 Life Member Platinum Subscriber QRZ Page

    I very strongly suspect this transmitter is simply an oscillator module. V+, V-, RF output... just key it on and off to send. But it's just a square wave computer-board oscillator. Hence the comment about the option to add the LPF to really make it be right. It's very likely just a crystal oscillator module for PC boards, using one of the trillion oscillator modules made for computer networking products - available all over the internet for a dollar or less each.

    Just a hunch but I'd bet not far off.

    Nothing wrong with that - I'm not putting it down. Just suggesting the strong likelihood of what it is. These modules have been around for years and turn up on eBay as "QRP Transmitters" all the time.


    AG5DB, N7ANN and KI6USW like this.
  3. KD7BBO

    KD7BBO Ham Member QRZ Page

    This could be an excellent fox hunting transmitter
    KH2SR likes this.
  4. WB0RIO

    WB0RIO Ham Member QRZ Page

    I agree, if you release the schematic you will probably get free advice from a bunch of hams and that could be used to improve your gadget.
    Note that there are now programmable oscillator modules available that can be factory set to a wide range of frequencies.
  5. KC8YLT

    KC8YLT Ham Member QRZ Page

    Like what you are doing, this is what it is all about! Good luck!
    KH2SR likes this.
  6. KH2SR

    KH2SR Ham Member QRZ Page

    I'm running a 6 day twitter poll to determine which band to offer next for my KeychainQRP project.

    If anyone is willing, just click the link below to cast your vote.

    Thanks in advance to all who vote!


    Jim - KH2SR
  7. KD8YQC

    KD8YQC Ham Member QRZ Page

    You would probably get a lot more feedback if your poll didn't require people to sign up for a service. I would suggest setting up an online poll at a site like this:
    KH2SR likes this.
  8. KH2SR

    KH2SR Ham Member QRZ Page

    Thanks for the link!

  9. KF5FEI

    KF5FEI Ham Member QRZ Page

  10. K8AI

    K8AI Ham Member QRZ Page

    You may be able to do better with stuffing a surface-mount-component version of one of those cheap Pixie transceivers in your keychain-sized enclosure. That way, you could choose a more popular QRP frequency and add a receiver to boot. It's definitely doable.
    VE7JBX and KH2SR like this.

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