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Re: [softrock40] Re: 14.100 at 48 kHz rate ...and other frequencies

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  • Kees & Sandy
    True, Valpey-Fisher makes good stuff but it s a much more expensive. That s also the clock specification (digital output) which is even better than just a sine
    Message 1 of 5 , Aug 30, 2007

      True, Valpey-Fisher makes good stuff but it's a much more expensive. That's also the clock specification (digital output) which is even better than just a sine wave spec because you
      would still have to trigger digital logic VERY repeatably to avoid adding more jitter. 

      The comparator output (which is a good one) on the AD9851 is spec'd to have a typical output jitter of <80ps. I wonder what the jitter is on a SoftRock at the output of the first FF where you have your first digital signal ?  or better yet, at the switches ? 

      I think you will find that the digital jitter on a SoftRock (at the switches), when using a crystal oscillator or a DDS-60 as the LO, is substantial .......but I don't have any numbers. It may make +/-50ps look pretty good. And, although it matters, it really does not seem to effect  SoftRock operation to a great degree. 

      73 Kees K5BCQ 

      -- "w5sxd" <rca@...> wrote:

      50 ps is terrible phase jitter. The 200 MHz oscillator in the sdr-
      1000 is specified at less that one ps. I believe it is a Valpey-
      Fisher vf-160 and it's not cheap.

      Richard W5SXD

      --- In softrock40@yahoogro ups.com, "Kees & Sandy" <windy10605@ ...>

      > Has anyone tried the little ECS programmable oscillators (uses a
      crystal and one time programmable PLL). They are available for $6.70
      any frequency from 1Mhz to 150Mhz and are programmed for your
      specified frequency. Available in 8 pin DIP or SMT.
      > Data sheet says +/-50pS jitter if >33.1Mhz.
      > Costs a lot more than a crystal but maybe not a custom crystal.
      > 73 Kees K5BCQ
      > -- "n2pk2001" <paul@...> wrote:
      > Hi Ray,
      > > I too would like to order a xtal from ICM. Could you please give
      > > the required xtal specifications that I will need to make the
      > > I will be ordering for a freq. of 14.100 and 14.220.
      > First I went to:
      > <http://www.icmfg. com/crystal_ hc49u.html
      > and saw that ICM's max Rs was 40 ohms at 3rd overtone for a 56.8 MHz
      > crystal. So I just sent them an email with: "I'd like to get a price
      > quote and delivery time for ONE 56.8 MHz, 3rd overtone, series
      > resonant, HC-49/U crystal. Nothing fancy."
      > I'll test the one I got in the next day or two for Rs and Fs.
      > 73,
      > Paul, N2PK

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