GPS Referenced Oscillator Project

Discussion in 'Amplitude Modulation' started by W8KHK, Oct 12, 2018.

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  1. KL7AJ

    KL7AJ XML Subscriber QRZ Page

    Don't give WWV the last rites yet.....but it's always good to have an alternative. :)
  2. W8KHK

    W8KHK Ham Member QRZ Page

    The last I heard WWV was not going to be de-funded. Now celebrating 100 years as the oldest continually-operating transmitting station.

    But this toy I built one year ago sure is convenient! Pretty much eliminates the need for an accurately-calibrated dial in the older receivers. And it makes an excellent external clock reference signal for counters and lab generators.
  3. W1JTO

    W1JTO Ham Member QRZ Page

    A few questions:

    Are these boards that simplify the QEX article available ?, i.e. can I buy one from you ?

    Is the enclosure readily available ?.

    If I recall these square waves need to be converted to Sine waves and amplified to 5-7 volts p-p for receivers or as much as 20v p-p for transmitters... do you have this circuitry on the board ?.

    I would be very exited to build this...

    73 John W1JTO
  4. W8KHK

    W8KHK Ham Member QRZ Page

    John, the board for the QEX article is still available, the universal board is not. As you can see from the photographs, a coaxial cable passes directly from the DDS module to the output jack on the back of the enclosure, so there is no signal processing in this implementation.

    If you wish to build it, I would suggest using the less-expensive NEO-6M or similar GPS module, and mount it directly on the back panel. There is a minor issue with using the more expensive AdaFruit GPS module.

    The enclosure I used is just an old Bud MiniBox from my junk-box. It has a few small round holes, and one larger rectangular cutout for the display, which was drilled and filed to size. In the soft aluminum, the drilling and blasting goes rather quickly.

    If using the device as a reference oscillator, the square wave works just fine. As a local oscillator, it would need to be filtered to a sine wave. A band-pass filter does this nicely. For transmitting, an amplifier is required, but the square wave should not be an issue as it will be cleaned up naturally by the driver and the final tank.

    If you are interested in more information, you may contact me at w8khk at arrl dot net or wb4gnr at gmail dot com.

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