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Calibrate Local Oscillator in my 6400M

Andy W3LI
Andy W3LI Member ✭✭
edited April 2020 in FLEX-6000 Signature Series
Staying at home like everyone else I decided to Cal the local oscillator as per the user manual pg 130. It does not say but I will assume that this is done in the AM mode as WWV transmit AM.
I set the Cal frequency at 15 mhz as it gave me a signal of S8&9. The Offset came back as -953.
Is that -953 hz in parts per billion? Manual does not say.
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Answers

  • HCampbell  WB4IVF
    HCampbell WB4IVF Member ✭✭
    edited April 2020
    Yes, its ppb, and from what I recall if you're not getting an error msg it's within specs.
  • Andy W3LI
    Andy W3LI Member ✭✭
    edited April 2020
    OK, Thanks for the confirmation as the manual does not mention such.
  • Robert Lonn
    Robert Lonn Member ✭✭
    edited April 2020
    I did check WWV this morning and it seems to be on frequency, if not I usually call them and tell them to adjust C-1 on their Master Oscillator! When I get exactly 10.00000000000 MHz, they stop adjusting and we are good to go!!!! LOL  :-)   Happy Sunday!!




  • Al K0VM
    Al K0VM Member ✭✭✭
    edited April 2020
    -953 ppb is -953 hz at 1 Ghz  or  -9.53 hz at 10 Mhz

    AL, K0VM
  • Andy W3LI
    Andy W3LI Member ✭✭
    edited April 2020
    Sure U do.....April Fools
  • KC2QMA_John
    KC2QMA_John Member ✭✭
    edited April 2020
    What are typical ppb offset numbers people see with 6400/6600?
    mine is -1105.
  • Andy W3LI
    Andy W3LI Member ✭✭
    edited April 2020
    Hi John, long time no hear.
  • Al K0VM
    Al K0VM Member ✭✭✭
    edited April 2020
    John,
      My 6600 is -1341 ppb this morning..  the spec for the 6400/6600,  as I read it, is for stability 0.5 ppm 0-50C, accuracy and long-term drift are not specified.
    AL, K0VM
  • KD0RC
    KD0RC Member, Super Elmer Moderator
    edited April 2020
    Mine was a little over 1200. I have since connected a GPSDO and it came in at zero when calibrating with WWV at 20 MHz. I have recalibrated a couple of times to see if this is a fluke, and it has stayed at zero. 73, Len, KD0RC
  • Dwayne_AB6A
    Dwayne_AB6A Member ✭✭
    edited April 2020
    I use an external GPSDO. 
  • KC2QMA_John
    KC2QMA_John Member ✭✭
    edited April 2020
    OK so around 950 to 1500 is normal for the stock internal local OSC?
  • Dwayne_AB6A
    Dwayne_AB6A Member ✭✭
    edited April 2020
    -1347 with the internal TCXO and -7 with the external GPSDO on 10Mhz.
  • KC2QMA_John
    KC2QMA_John Member ✭✭
    edited April 2020
    I think as i get more into digital modes I will look into a GPSDO.
  • Al K0VM
    Al K0VM Member ✭✭✭
    edited April 2020
    As long as it stays in the range that the software cal is able to correct, it should be fine..  Not sure what that range  is though.
    AL, K0VM
  • Brian Denley  KB1VBF
    Brian Denley KB1VBF Member ✭✭
    edited April 2020
    Mine is zero (No lie!) with an external GPS.
  • KC2QMA_John
    KC2QMA_John Member ✭✭
    edited April 2020
    WOW Brian, what GPSDO are you using?
  • Brian Denley  KB1VBF
    Brian Denley KB1VBF Member ✭✭
    edited April 2020
    BG7TBL one on EBay.  About $150.  I did have to buy the cable to attach to the Flex 10 MHz input conn.  After the setup and the GPSDO and my Flex said they were both locked, I basically pushed the cal button and it came back at 0 at 10 MHz.  Kinda surprised me.
  • Dwayne_AB6A
    Dwayne_AB6A Member ✭✭
    edited April 2020
    Mine is 4 on 10Mhz this minute but the Flex will return 0 if it does not find a signal to sync to.
  • Brian Denley  KB1VBF
    Brian Denley KB1VBF Member ✭✭
    edited April 2020
    Since the Flex said it was locked on external, can I assume it found the signal?
  • Dwayne_AB6A
    Dwayne_AB6A Member ✭✭
    edited April 2020
    No - Note how the radio will switch frequency to calibrate. 10MHz should be good!
  • Brian Denley  KB1VBF
    Brian Denley KB1VBF Member ✭✭
    edited April 2020
    No? You don’t think locked means it sees the 10 MHz external GPSDO?
  • Dwayne_AB6A
    Dwayne_AB6A Member ✭✭
    edited April 2020
    No means Yes it is locked on GPSDO, but calibration requires you enter 10 (Mhz) and click Start next to the Call Frequency. The radio will then test calibration against a 10 Mhz reference signal. It will then adjust offset in ppb. Click start and let us know what it says. Mine this minute is bouncing between -3 and +4. Essentially noise, but not 0. A cold GPSDO will have a much higher value but better than the internal TXDO. It would be surprising it always comes back 0 but as a warning, if it does not find a signal (wrong antenna etc) it will come back 0. image
  • Brian Denley  KB1VBF
    Brian Denley KB1VBF Member ✭✭
    edited April 2020
    Dwayne:
    OK yes that's what I did (press start) and it came back with zero.  I'm sure if I do it again i'll get 10 or 7 or -15.  But I did like seeing that zero!  hehe
  • Brian Denley  KB1VBF
    Brian Denley KB1VBF Member ✭✭
    edited April 2020
    image
  • Dwayne_AB6A
    Dwayne_AB6A Member ✭✭
    edited April 2020
    That’s awesome!
  • Geoff AB6BT
    Geoff AB6BT Member ✭✭✭
    edited April 2020
    This is all very interesting. I have a question. What are the practical differences when using a DSPDO? If the radio is capable of of generating an offset to a known frequency standard, WWV for  example, What is the advantage of using a GPSDO?
  • Brian Denley  KB1VBF
    Brian Denley KB1VBF Member ✭✭
    edited April 2020
    Not that much Geoff.  I'm not sure you really care whether your contact is 5 Hz off or .00005 Hz off.  I like mine for the frequency calibration and also the time keeping which is exact.
  • Dwayne_AB6A
    Dwayne_AB6A Member ✭✭
    edited April 2020
    There is a frequency test contest conducted several times a year. I hope to compete this year.
  • Dwayne_AB6A
    Dwayne_AB6A Member ✭✭
    edited April 2020
    GPSDO has a high degree of stability and accuracy over and above the standard TXDO. IMO, really only matters at UHF and beyond.
  • George KF2T
    George KF2T Member ✭✭✭
    edited April 2020
     GPS is helpful for transverter operation. For HF/6, the stock configuration is absolutely fine. 

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