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Leo Bodnar GPSDO and noisy power supply

KD0RC Member, Super Elmer Moderator

In case anyone else is experiencing this, I thought I would share. I bought a Leo Bodnar GPSDO, set it up for 10 MHz and connected it up to my Flex 6400. I powered it from a switching power supply, and it worked great - it put the Flex right on frequency within just a few PPB. So far so good.

I started noticing some bad noise peaks, but I could null them out with my ANC-4 noise canceller so I didn't think further about the origins of the noise. I needed my little switcher for a project, so I plugged the GPSDO into a USB port on my desktop computer. The noise peaks were gone! I can even run the switcher without causing noise in my receiver. It is the combination of a noisy power supply feeding the GPSDO that causes the problem.

So, if you get an external 10 MHz reference, be sure that it is using a clean power supply.


Len, KD0RC


  • I have 6700. and have the http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=107&products_id=301 connected to the radio. How do I get the radio to ""see" the GPS? I can run the gps program. I I have good lock with accurate info. Output set to 10Meg. Thanks Roger

  • KD0RC
    KD0RC Member, Super Elmer Moderator

    Hi Roger, In SmartSDR, go to Settings, Radio Setup and set the source to Auto or External 10 MHz. Make sure the GPSDO is set to 10 MHz and connected to the 10 MHz In jack on the back pf the radio. Once you are all hooked up, choose a WWV frequency that you can hear at your location, and press the Start button. I am only about 50 miles from WWV, so the 2.5 MHz transmissions work great for me. Note that the frequency calibration only uses the ANT1 connector.

  • The 6700 is not as good as the 6400. I dont show the option for external source. The 6700 is a lame duck in a lot of ways.

  • KD0RC
    KD0RC Member, Super Elmer Moderator

    What version are you running? Mine is 3.1.12. What does your RX tab look like in Radio Setup?

  • WX7Y
    WX7Y Member ✭✭✭

    I have to disagree with you Roger, the 6700 AUTOMATICALLY Connects to the 10MHZ external source when you power up the radio, YOU DO NOT have to select anything, if the 10MHz goes out of specs then it will select the internal TCXO or if you have the Internal GPS automatically.

    I have a 6600 and a 6700 signature series radio and the 6700 get's ran 24/7 and the 6600M is just the Backup / loaner radio do to the things it is lacking.

    If I was to sell one of them it would be the 6600M.

    For me the RX loop's are a must for different band filters, Broadcast band notch filters and front end overload protection etc. which was left out of the 6400 and 6600 which are much better filtering options then the one built into the 6400 / 6600.

  • Anyone want to buy this mini GPS. It will not work on the 6700. I paid $140. I'll take $100 for it.

  • Roger Rockwell/na4rr
    Roger Rockwell/na4rr Member ✭✭
    edited March 2021

    Sorry for dup

  • arodland
    arodland Member ✭✭

    Great advice, Len. I ran into the exact same problem with my LeoNTP. I was powering it from a cheap 12V-to-USB adapter that I got who-knows-where, and the frequency lock was fine, but one day, just like you, I unplugged it and noticed that a whole lot of QRM was gone. I plugged it into a phone charger and... I guess it's an okay phone charger, because I don't get noise introduced on my 10MHz anymore.

  • KD0RC
    KD0RC Member, Super Elmer Moderator

    Glad I could help! I have been really happy with my GPSDO. I need it more for my spectrum analyzer, but it is nice to have it available for use with the radio.

  • Allen K4VA
    Allen K4VA Member
    > @KD0RC said:
    > Hi Roger, In SmartSDR, go to Settings, Radio Setup and set the source to Auto or External 10 MHz.

    Is this with an external GPS? I'm trying to set up a Bodnar, Output 1 selected, set at 10 MHz, and Output Drive Strength set at 32mA, but do not have the "10 MHz Reference" submenu. I'm running SmartSDR 3.4.21.
  • Martin_G4ENZ
    Martin_G4ENZ Member ✭✭

    It is under the RX tab.

    This is a Bodnar unit.

    73 Martin

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