Designing a Radio to Detect Jupiter

Discussion in 'The Projects Forum' started by Sparky49, Jun 4, 2015.

  1. Sparky49

    Thread Starter Active Member

    Jul 16, 2011
    834
    417
    Hi all.

    Exams are over and I've got some time to spare. What better way to start my holidays than with some electronics? :D My uni has a lot of flat, open fields, so I thought this would be a good opportunity to try something with some big (~8m dipole) antennas that I couldn't put up at home.

    I've known about the Radio Jove project for some time now, but have been put off by the hard to find varicap and inductor values, and was wondering how to design a more 'modern' version. However, whilst I appreciate how this particular circuit works, and how a few different receivers work from my comms module, I do not know how to go about designing such a circuit. I did think about using one of those DTV USB dongles, but none seem to go down to such low frequencies.

    I thought a good place to start would be to examine the Radio Jove specs, which can be found on the last page of this document:

    http://radiojove.gsfc.nasa.gov/telescope/rcvr_manual.pdf

    In short, we are after:

    Gain >100dB
    BW ~ 7kHz
    NF 6dB
    Aiming to tune around 20.1MHz

    I think I get why most of the components are where they are, but there are some that throw me off and make me uncertain, for example the JFET on the RF input.

    If anyone could help me get started, I would really appreciate it. Even if it is a case of focusing my efforts into one piece at a time (ie, you're going to need an input filter, go and design something that will filter between here and here, come back and show us for critique), I would really appreciate it.

    Thanks alot for your time, it is really appreciated.

    Regards,

    Sparky
     
  2. nsaspook

    AAC Fanatic!

    Aug 27, 2009
    2,907
    2,165
    Sparky49 likes this.
  3. Sparky49

    Thread Starter Active Member

    Jul 16, 2011
    834
    417
    Thanks nsaspook, did you find the dongle drifted a lot, or was it not too noticeable?
     
  4. nsaspook

    AAC Fanatic!

    Aug 27, 2009
    2,907
    2,165
    There was some drift when first powered up but the WWV calibration procedure using the SDR receiver program offset fixed that after everything was stable. Most people strip the dongle, install it in a shield box away from the PC and filter the USB power to reduce EMI.

    https://www.flickr.com/photos/nsaspook/sets/72157632883630584
     
    Sparky49 likes this.
  5. Sparky49

    Thread Starter Active Member

    Jul 16, 2011
    834
    417
    Nice one, and it should be good to work within those parameters above (plan to couple it with a dipole pair)?
     
  6. nsaspook

    AAC Fanatic!

    Aug 27, 2009
    2,907
    2,165
    Sparky49 likes this.
  7. Sparky49

    Thread Starter Active Member

    Jul 16, 2011
    834
    417
    Okay, thanks for the google groups link.

    I'm planning to use SDR# - used it with success to decode NOAA telemetry.

    Can you recommend a good LNA? This is all very exciting! :D
     
  8. nsaspook

    AAC Fanatic!

    Aug 27, 2009
    2,907
    2,165
  9. Veracohr

    Well-Known Member

    Jan 3, 2011
    550
    75
    Top of page 6.
     
Loading...