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Is it possible to phase lock two Flex-6400's or Flex-6600's?

Hi All,
I have been looking through the archive - I have found good info on the use of external references and phase noise, but I haven't seen info to answer the following:

Using the external reference or the internal GPSDO is it possible to phase lock two Flex 6400's or 6600's?

Note that I would like to phase lock the two radios on the bench, not just frequency lock them (that I think is achieved using the GPSDO or suitable external reference oscillator).
Thanks - John AF4ZE


  • Bill AB7AA
    Bill AB7AA Member ✭✭✭

    Hi John,

    I have two phase locked 6700 by virtue that they both locked to the same 10MHz Trimble Thunderbolt GPS reference oscillator. (As well as all of my test equipment)


    Bill AB7AA

  • KD0RC
    KD0RC Member, Super Elmer Moderator

    Might want to check with Flex to see if that actually locks phase.

  • rfjohn
    rfjohn Member ✭✭
    Hi Bill, Hi Len,
    Thanks for your quick input. Yes, I need phase locking (eg, on the same zero crossing of the ref input), and I am not clear on whether the radios do a frequency locking (where two radios may have a phase difference at the same frequency) or phase locking (both the frequency and absolute phases are matched). Yes, I may need Flex tech experts to chime in!
    Thanks though - I am getting closer!
    John AF4ZE
  • Bill AB7AA
    Bill AB7AA Member ✭✭✭

    I can tell you that you can not hear any frequency beating of a single tone received by the two different radios. They are coherent. A phase difference, however, can always be measured depending on the total signal path difference from the source to the end measuring device, between the two receiving systems.

    Bill AB7AA

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