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Flex 5000 External Frequency Reference Requirements Sine or Square?

I am looking to add an external frequency reference to my my Flex 5000 and wish to know if the reference input requirement on the Flex 5000 or 1500 is sine wave or square wave? There seems to be discussion on the web at various places that sine wave is required but I would like an official response.  Thanks, Scott


  • John KB4DU
    John KB4DU Member ✭✭✭✭
    edited December 2019
    FWIW, the Flex 6XXX hardware manual states Sine or Square wave, 1V-3.3V P-P.
  • Scott Greenwalt
    edited December 2019
    I'm hoping the 5000 is the same but I'm having doubts from what I have found online.   Also could not find the requirements specs in the copy of the manual I have for the 5000.  
  • Alan WA4SCA
    Alan WA4SCA Member ✭✭
    edited December 2019
    Not a real answer, but you can "convert" a square wave to a sine wave with a simple filter.  The next higher frequency component in the square wave is 3X times the fundamental, at 1/3 the amplitude.  You can find 10 MHz filters on eBay for $10 US or so, or roll your own.  I have done this in the past with test equipment, though not with a Flex.
  • George KF2T
    George KF2T Member ✭✭✭
    edited December 2019
    All things being equal, I’d go with sine wave. Not too many things that work with square wave won’t work with sine, although the reverse may not be true.
  • Scott Greenwalt
    edited January 2020
    UPDATE:  Still not sure about the requirement for the 5000, but I converted the square to a sine wave using a Down East Microwave filtered and amplified divider, and the Flex is happy with it, plus I can now use the same reference with my transverters.   Thanks to all for the assistance.

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