Posted by
David Box-2 on
Jun 05, 2018; 5:48pm
URL: http://elecraft.85.s1.nabble.com/K3S-XREF-GPSDO-recommendation-needed-tp7641686p7641710.html
I have one of Bodnar's units and works well. The software is clunky but
usable. There is a way to set other frequencies than what the pulldown
menus offer. You need to go to and download a copy of the DSPLLsim
utility in order to calculate the correct coefficients..
Below is a set of steps that Jan Verduyn has published that allows
setting the two ports to other frequencies, in this case he was trying
to get 10Mhz and 36MHz but using DSPLLsim you can work out other pairs.
DSPLLsim is at
<
https://www.silabs.com/products/development-tools/software/clock>
If you only need one frequency then Bodnar also sells a smaller unit
<
http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=107&products_id=301>
that is lower priced. AirSpy also sells this unit.
Dave K5MWR
From Jan Verduyn instructions for tailoring frequencies.
Setting of the GPSDO Output 1 to 10MHz and GPSDO Output 2 to 36.000 MHz
as external clock for the VNWA is done as follows:
Start the GPS clock application for the Leo Bodnar standard 2 port GPSDO.
1. Set output 1 and output 2 to 10000000 Hz = (10 MHz)
2. Make sure both outputs are enabled
3. Press “Find” and both output should be locked and produce 10.000 MHz
4. Now change the register details as shown below by typing in the
following data:
10000000 = GPS Reference Hz
5 = N31
6 = N2_HS
450 = N2_LS
5 = N1_HS
108 = NC1_LS
30 = NC2_LS
0 = Phaseshift degrees (unchanged)
15 = BW unchanged
5. next press “Update” button and both outputs should show red – locked
6. If you measure with Frequency meter you will find that output 1
produces 10 MHz and Output 2 will produce 36 MHz.
Note that the output 2 indication will continue to show 10 MHz, which is
wrong. It should read 36MHz.
These settings are stored when you switch off the GPSDO, When you apply
power to GPSDO at a later date the same frequencies should be produced.
Remember however as soon as you press the “Find button” the settings
will be lost and will need to be re-entered.
If GPS Signals are lost then the output frequencies are derived from the
built-in TCXO with the last correction factor applied before lock was lost.
The above register settings were obtained using DSPLLsim utility.
Make sure you select the SI5328 to obtain the correct settings.
Attached is a screenshot of the GPS Clock Configuration screen.
Good luck.
Jan G5BBL SDR-Kits
On 6/5/2018 7:38 AM, Wes Stewart wrote:
> I'm using it for other purposes but I have one of these and it's fine.
>
> The only downside is the very clunky software and the sometimes
difficulty of getting the two frequencies out that you might want. For
10MHz only, it's a piece of cake.
>
> Wes N7WS
>
> On 6/5/2018 4:49 AM, Joe DeVincentis wrote:
>> I have have this one and no complaints:
>>
>>
https://v3.airspy.us/product/lb-gpsdo-1/ >>
>> 73,
>> Joe, KO8V
>>
>>> On Jun 5, 2018, at 12:08 AM, eric norris via Elecraft
<
[hidden email]> wrote:
>>>
>>> Dear Gang:
>>> A shiny new K3S has joined my Elecraft herd, though K3 #2545 is
still going strong. I have been getting confused looking at GPSDOs, and
wonder if someone can recommend a plug and play (or close as
practicable) GPSDO for me to buy.
>>> 73 Eric WD6DBM
>>>
>>>
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