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Help needed with forty 9er dds vfo conversion

Discussion in 'Homebrew and Kit Projects' started by KD9GGZ, Sep 6, 2021.

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  1. KD9GGZ

    KD9GGZ Ham Member QRZ Page

    I checked the dds output with an oscilloscope and it was fairly clean.
     
  2. W1VT

    W1VT Ham Member QRZ Page

    A tougher test would be to listen to the DDS on a quality receiver.

    A cheap receiver may be misleading because you may be listening to issues with the receiver's oscillators.
     
    Last edited: Sep 6, 2021
    N2EY likes this.
  3. KD9GGZ

    KD9GGZ Ham Member QRZ Page

    Well I think the problem might be with not enough drive from the dds. Also I hear the noise problems with or without a signal source present but only on recieve. I can't hear any issues on transmit when receiving on a icom 718
     
  4. KB1CKT

    KB1CKT Ham Member QRZ Page

    I know DDS has spurs (due to the DAC updating) but not sure on PLL's. Which the SI5351's are. Maybe the PLL does, depending on the divide ratios? Not worrying about harmonics, just spurs.

    Cobbled up a SI5351 last night and just tacked on a clip lead, didn't sound bad in a receiver, listening just to the fundamental. Didn't get past that (yet).
     

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