[NLRS] GPS Disciplined Osc

[Chris Elmquist]

Of note, the Leo Bodnar unit that Jon asked about is _very_ frequency
agile on the phase locked output.  You can set it up, using a simple
Windows app, for any output frequency between 400 Hz and 800+ MHz.  So,
it's a little different than a GPSDO that has a fixed 10 MHz output.

I chose it for this reason because it is very simple to lock an older
radio, such as the FT736, which needs a 20.48 MHz clock rather than
anything close to 10 MHz.  I have already done similar on an IC-746PRO
using a home built PLL for 32.0 MHz.  Had this "Mini GPS" been available
long ago, I would have chosen it instead, programmed its output to 32.0
MHz and been done with it.

The Mini GPS has pretty good phase noise characteristics too--

Typical phase noise at 10MHz output:

-70 dBc/Hz at 1 Hz
-100 dBc/Hz at 10 Hz
-125 dBc/Hz at 100 Hz
-145 dBc/Hz at 1 kHz
-150 dBc/Hz at 10 kHz
-153 dBc/Hz at 100 kHz
-155 dBc/Hz at 1 MHz

He uses an Si532x device as the programmable PLL following a U-Blox GPS
receiver.

There is a review here of the dual-output Bodnar unit from which the Mini
was derived.  The application software for setting up the Mini is very
similar, if not identical,

http://leobodnar.com/files/Informal%20Evaluation%20of%20a%20Leo%20Bodnar%20GPS%20Frequency%20Reference.pdf

Chris NØJCF


On Monday (11/23/2020 at 11:42AM -0600), Lloyd - N9LB wrote:
> Thanks for the tip.  I just placed a bid.
> 73
> Lloyd-N9LB
> 
> -----Original Message-----
> From: nlrs-bounces at mailman.qth.net [mailto:nlrs-bounces at mailman.qth.net] On
> Behalf Of Gregg Lind
> Sent: Monday, November 23, 2020 11:33 AM
> To: Jon Platt <w0zq at aol.com>
> Cc: nlrs at qth.net
> Subject: Re: [NLRS] GPS Disciplined Osc
> 
> Here is what a number of folks here in Cedar Rapids have purchased.
> 
> https://www.ebay.com/itm/SAMSUNG-STP-2945-LF-GPSDO-10MHz-1PPS-OCXO-GPS-Disci
> plined-Clock-w-ublox-LEA-6T-/264929130244?_trksid=p2047675.l2557&ssPageName=
> STRK%3AMEBIDX%3AIT&nma=true&si=GAojT7ivY6xKu9RXhQtgeuGSBmY%253D&orig_cvip=tr
> ue&nordt=true&rt=nc
> 
> On Mon, Nov 23, 2020 at 9:42 AM Jon Platt via NLRS <nlrs at mailman.qth.net>
> wrote:
> 
> > Anyone have any hands-on experience with the SDR Kit "Low Jitter 
> > Precision GPSDO Reference Oscillator" ?
> > See
> > https://www.sdr-kits.net/GPS-Disciplined-Reference-Oscillator-for-DG8S
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-- 
Chris Elmquist