[time-nuts] Programmable clock for BFO use....noise

Mark Goldberg marklgoldberg at gmail.com
Sun Sep 16 14:00:58 EDT 2018


For a radio BFO you want something with low phase noise (low jitter). The
SI5351 is not designed for that, and it's jitter spec is 70 ps, which is
pretty noisy. It even has a spread spectrum mode that would be even worse.
They do have other parts designed for low jitter (< 1ps). Leo Bodnar's
GPSDOs with variable output clock frequencies are based on  those chips and
they provide low phase noise, certainly enough for a radio.

Regards,

Mark


On Sun, Sep 16, 2018 at 10:22 AM, Chris Waldrup <kd4pbj at gmail.com> wrote:

> How about using a ProgRock on Hans Summers QRP Labs website? This is a
> programmable crystal replacement.
>
> Chris
> KD4PBJ
>
> > On Sep 14, 2018, at 8:06 PM, paul swed <paulswedb at gmail.com> wrote:
> >
> > The beauty of a $2 arduino and a drop of code snitched from Engineer
> google.
> > OK enough of that back to the thread.
> > Regards
> > Paul
> > WB8TSL
> >
> >> On Fri, Sep 14, 2018 at 8:04 PM, Mike Feher <mfeher at eozinc.com> wrote:
> >>
> >> Not when I built them in the late 60's and early 70's. All discrete. 73
> -
> >> Mike
> >>
> >>
> >>
> >> Mike B. Feher, N4FS
> >>
> >> 89 Arnold Blvd.
> >>
> >> Howell NJ 07731
> >>
> >> 848-245-9115
> >>
> >>
> >>
> >> -----Original Message-----
> >> From: time-nuts <time-nuts-bounces at lists.febo.com> On Behalf Of Richard
> >> (Rick) Karlquist
> >> Sent: Friday, September 14, 2018 7:15 PM
> >> To: Discussion of precise time and frequency measurement
> >> <time-nuts at lists.febo.com>; ed breya <eb at telight.com>
> >> Subject: Re: [time-nuts] Programmable clock for BFO use....noise
> >>
> >>
> >>
> >>
> >>> Finally, of course, you can use DDS. This is nearly an ideal case for
> >>
> >>
> >>
> >> The trouble with a DDS is that you need a microcontroller with software
> >> just
> >> to baby sit the thing.
> >>
> >>
> >>
> >> Rick N6RK
> >>
> >>
> >>
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