GPSDO DXPatrol

Hi,

the AD 9363 data sheet says

Reference clock Input Signal Level 1.3 V p-p AC-coupled external oscillator

That is the typical value, no min or max given.

Detlev

Hi,

I am just building a reference clock with a 10 MHz OCXO, an Arduino nano and a Si 5351 synthesizer, which produces 25 MHz for the LNB and 40 MHz for a Pluto Rev. C.

73, Detlev

DC7KG Hallo Detlev,

welche Version des Si5351 verwendest Du und auf welchen Clock-Eingang geht die 10MHz Referenz? Funktioniert die Schaltung bereits?

Aktuell habe ich einen OCXO mit 2x AD9850 DDS Chips zur Erzeugung von 2 Frequenzen. Wenn der Si5351 mit 10 MHz sauber funktioniert, wäre das eine einfachere und billigere Lösung, die ich bei Gelegenheit mal testen würde.

Gruß
Armin

Hello Armin,

you can use this board, click! : SI5351

There are examples in the net, saying to cut a trace and use output 2 as the input. I recommend not to do this. If you need 2 frequencies, the calculation program might advice you to use output 0 and 2, not output 0 and 1.

Remove the 25MHz TCXO and feed 10MHz via a capacitor.

Download the SiLabs Clock Builder Software . Cheat the clock builder software by telling it you are using the SI5351 with 8 outputs and reference input.

You will need a clean power source and you might need low pass filters at the outputs. I tested it with 24 or 25 MHz output plus 116MHz for my transverter, it works.

73, Martin

Hi Armin,

my clock generator isn't finished yet, but it works with DF7KB, who designed it.

I can help you with the Arduino files.

Detlev

Quote from DC7KG

Hi Armin,

my clock generator isn't finished yet, but it works with DF7KB, who designed it.

OK, looks like it is a type A Chip in a 10pin MSOP. The datasheet says 25/27MHz at the crystal input, not sure whether this input will work properly with 10MHz from the OCXO. This is the reason why I have not tried this yet and why I was asking. Best will be to make a prototype myself and find out.

73 Armin

Quote from dm4im

Hello Armin,

you can use this board, click! : SI5351

Hi Martin,

I have one of these boards at hand and will make a prototype with it.

Thanks for your detailled explanation.

73 Armin

Hi,

For driving a Pluto 10 MHz can be directly feed to it. There is no need to use 40 MHz. I use 10 MHz. Commands must be like:

fw_setenv ad936x_ext_refclk "<25000000>"

fw_setenv xo_correction 25000000

pluto_reboot reset

Hi George,

Does the computing power depend on the frequency?

73 Detlev

This is what I was trying to find out with this thread subject

Pros and cons of various Pluto external input frequencies??

I am still very curious as to what effect a different oscillator frequency might have with a Pluto, and whether 40 MHz is better than say 10 MHz. I did a lot of Googling but found nothing really relevant. Thanks.

Hi,

I suppose only one man can answer this question: Robin Getz.

https://twitter.com/robinlgetz?lang=de

Detlev

I am sure that many people could look at the schematics and spec sheets allowing a broadly accurate assessment of what effects changing the oscillator frequency may have. I'd ask on the Time-Nuts forum but they tend to go off at a tangent and leave me floundering in the wake of arguments and frankly unfathomable technical discussions in anything but plain English

If Mr. Getz were unfortunate enough to be run over tomorrow I am sure there are plenty of other technicians able to continue along his path. (That's not to say he isn't quite some clever guy :)) If we don't get any replies here I WILL ask on Time-Nuts, but may have to repeat any replies here in the hope someone can translate into language a dummy like I might understand!

Hi,

here is more information about this theme:

https://ez.analog.com/adieduca…/using-external-reference

https://ez.analog.com/adieduca…h-gps-clock/189670#189670

https://ez.analog.com/adieduca…-clock-to-the-adalm-pluto

Regards,

Detlev

Based on the AD9361 reference manual, I think 40 MHz is the magic number that allows the PFD to run at 80 MHz using the internal doubler.

AD9361 Reference Manual

They recommend running the PFD as close as possible to 80 MHz. 40 MHz is the lowest you can go while stil achieving 80 MHz.

Hi,

you got it! Very good! UG570 explains it!

Regards,

Detlev