[NLRS] GPS Disciplined Osc

[Jon Platt]

Thanks Chris and others for comments.  This may be useable for a GPS locked LO for my older DB6NT 10 GHz unit where the LO is crystal based at 106 MHz (as I recall).
73, JonW0ZQ


-----Original Message-----
From: Chris Elmquist <chrise at pobox.com>
To: Lloyd - N9LB <lloydberg at tds.net>
Cc: nlrs at qth.net; 'Jon Platt' <w0zq at aol.com>
Sent: Mon, Nov 23, 2020 1:40 pm
Subject: Re: [NLRS] GPS Disciplined Osc


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