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Stargazing Itty Bitty Radio Telescope

  1. Apr 22, 2009 #1
    I'm putting together the Itty Bitty Radio Telescope. In the instructions (see: http://www.aoc.nrao.edu/epo/teachers/ittybitty/procedure.html), it says to use a .1Mhz RF Choke. I have been unable to locate this particular frequency, as the only one I have been able to locate has been a 1kHz RF Choke? Can anyone help me? Was it a typo or do I actually need a .1MHz RF Choke?
  2. jcsd
  3. Apr 23, 2009 #2


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    I can make the following suggestions:
    *Try the 1kHz choke... it should filter all frequencies above 1kHz so may be even more efficient then the suggested .1Mhz choke.

    *Check around the web for designs for home-made RF Chokes.

    The point of the choke is to prevent the battery clips from acting as an antenna picking up ambient microwaves (i.e. nearby cell phones etc). So...

    *You may be able to replace the choke with a shielded enclosure for the batteries. In fact this may work even better but I'm not up to speed on microwave circuit issues (only broad theory) so can't say for certain. Try finding an aluminum enclosure with a coax junction which will hold your batteries.
  4. Apr 23, 2009 #3
    Thanks, have you built this type of radio telescope already?
  5. Apr 23, 2009 #4


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    No but it looks interesting. I've bookmarked the link and may try it this summer.
  6. Apr 24, 2009 #5


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    you need an adjustable choke [tuning coil]. i havent built one of these things either, but, it is little more than a low frequency ham radio with a funny antenna and extra shielding.
  7. Jun 11, 2009 #6
    I'm new to the forum having I stumbled upon it looking for add'l info on the IBT. I believe the choke you are looking for is a 0.1mH or 100uH choke. I think the information published on the 'How to build' sheet was in error.

    I'm a physics teacher looking for some new ways to excite the students. I think working with a radio telescope will help in the understanding of the EM spectrum and provide a different way of doing physics in this area We'll see.

    Take care,

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