10MHz GPSDO by "BH3SAP"

[KungFuJosh]

Yes, that seems to be normal.

[Kurt_!]

Maybe I need to change the OSC as well.

I have enough CTI, but whether they are that good?

[KungFuJosh]

Mine is with the ISOTEMP, which I think you said you have?

You can always test other OCXOs. You gotta leave them running at least a few days though.

[Kurt_!]

This one is inside OX256B.....

[KungFuJosh]

Oh, yeah, that's not awesome. Murder it! 

[Kurt_!]

This diagram is after half an hour of switching on.




no such strange up-down....

[KungFuJosh]

Was that already warmed up? Seems like a lot of initial drift if it was already warmed up. That's the bigger one?

[Kurt_!]

yes...half an hour

The little one....

always with internal osc and slightly adjusted.
Am Besten du probierst auch das Timelab aus, wenns geht bei dir.

Leo Bodnar also tested something...FA-2

https://www.eevblog.com/forum/metrology/bg7tbl-fa1-frequency-analyzer/msg3868613/#msg3868613

[Ringmodulator]

I also  own a a FA-2 and FA-3.

To analyse the ocxo behaviour, it is way better to use a tinyPFA. It als talks to Timelab.
In my opinion, this device has the best bang for the buck.
You can even get a (used) nanoVNA-h4 and flash the tinyPFA firmware.
Thats what I did.

https://www.tinydevices.org/wiki/pmwiki.php?n=TinyPFA.Homepage

Regards
Chris

[Kurt_!]

 have a few spares lying around, but I don't want to re-solder until I know which one is best for me.
I already have a good tool, but I don't think it's a good idea to solder too often.
I've already tested their frequencies. How close to 10 MHz they are...but I'm not much of an expert.


Ps.:
Are there comparisons ( OCXO ), what is still good and not good

[KungFuJosh]

I also  own a a FA-2 and FA-3.

To analyse the ocxo behaviour, it is way better to use a tinyPFA. It als talks to Timelab.
In my opinion, this device has the best bang for the buck.
You can even get a (used) nanoVNA-h4 and flash the tinyPFA firmware.
Thats what I did.

https://www.tinydevices.org/wiki/pmwiki.php?n=TinyPFA.Homepage

Regards
Chris

Do you mean to compare 1 OCXO vs another at the same time?

[Ringmodulator]

I also  own a a FA-2 and FA-3.

To analyse the ocxo behaviour, it is way better to use a tinyPFA. It als talks to Timelab.
In my opinion, this device has the best bang for the buck.
You can even get a (used) nanoVNA-h4 and flash the tinyPFA firmware.
Thats what I did.

https://www.tinydevices.org/wiki/pmwiki.php?n=TinyPFA.Homepage

Regards
Chris

Do you mean to compare 1 OCXO vs another at the same time?

Josh,

Yes and no. You can connect two oscillators and and  compare them against each other, but you cannot determine which one is "better".
This is generally a chicken/egg issue, unless you have a known better reference.

If you have three oscillators, you can measure, which combination has the best stability and identfy  the worst oscillator  of the three.

The videos from Eric, the author of the firmware, may give you an idea of the capability of this device.




Chris

[KungFuJosh]

Josh,

Yes and no. You can connect two oscillators and and  compare them against each other, but you cannot determine which one is "better".
This is generally a chicken/egg issue, unless you have a known better reference.

If you have three oscillators, you can measure, which combination has the best stability and identfy  the worst oscillator  of the three.

The videos from Eric, the author of the firmware, may give you an idea of the capability of this device.

I'm curious how a phase analyzer would be better to test a single OCXO vs a counter or oscilloscope or spectrum analyzer. I don't know much about the tinyPFA, but I thought the purpose was to analyze and test the phase difference between two signals.

I'll check out the video later.

Thanks,
Josh

[ME]

I have an old usb programing cable for programing a motorola gp-340 radio , can i hack that to send nima data to my pc?.cheers Me.

[SCSKITS]

An inexpensive GPSDO should be able to do 10MHz +/- 10mHz (10 millihertz). A better one should be able to do +/- 1mHz or 2mHz.

Not sure about the frequency offset you describe, the OCXO module on that board may be able to do +/- 50Hz from 10Mhz. Do they have another IC in line that can shift the frequency? Why would an offset be needed if used as a timing reference?

[Kurt_!]

In any case, you shouldn't expect too much from used OCXOs!
They don't get replaced after 10 years for nothing!
It's not always the quartz crystal that's to blame, as I've seen in my tests.
The internal electronics are also at fault.

[flash2b]

An inexpensive GPSDO should be able to do 10MHz +/- 10mHz (10 millihertz). A better one should be able to do +/- 1mHz or 2mHz.

My BH3SAP is +/- 1 mHz (see: https://www.eevblog.com/forum/testgear/10mhz-gpsdo-by-bh3sap/msg5639295/#msg5639295). The new firmware made all the other bits of this GPSDO just so much better.

[Kurt_!]

With Timelab you have better statements and stronger results !
Great program.

[Kurt_!]

From my FA-3



Gpsdo by BH3sap "The little one"

[KungFuJosh]

My peak to peak is 600uHz, so that's +/- 0.3mHz. Not too shabby.

[Kurt_!]

My peak to peak is 600uHz, so that's +/- 0.3mHz. Not too shabby.

You have two identical GPS devices, right?

[KungFuJosh]

My peak to peak is 600uHz, so that's +/- 0.3mHz. Not too shabby.

You have two identical GPS devices, right?

In theory, but one of them might need a repair on the GPS board. 

[Kurt_!]

One can be at peace...
...but an LBE-1421 by Leo Bonar would also be interesting.


Maybe there will be a promotion sometime?

[KungFuJosh]

One can be at peace...
...but an LBE-1421 by Leo Bonar would also be interesting.


Maybe there will be a promotion sometime?

The TCXO doesn't really interest me, especially not for the price. If it were in the same price range, then yeah, I'd probably have one already.

[Kurt_!]

You're right Josh! ( LBE )
I've swapped it twice now.
To CTI and now IsoTemp.
You can tell. Even when testing.
High output voltage and much closer to the target frequency.