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Author Topic: DDS Signal Generator  (Read 7188 times)
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kukumar
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« on: December 27, 2019, 01:17:18 13:17 »

I have new DDS signal generator FY6800
It is nice generator from 0.001Hz to 60 MHz. It has modulation capability,
(2 generators)
and is god for testing amateur receiver, but there is some problem
frequency has stability 20ppm and this may be a problem.
Problem is TCXO - 50MHz ,

My idea is to change this TCXO with better one.
Does somebody do this?
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PM3295
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« Reply #1 on: December 27, 2019, 03:25:14 15:25 »

You could easily get a used 25 MHz OCXO on eBay and use a mini-circuits frequency doubler.
Mini-Circuits-Model-RK-3-frequency-doubler sells on eBay for $15
https://www.minicircuits.com/WebStore/dashboard.html?model=RK-3%2B
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Magnox
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« Reply #2 on: December 27, 2019, 03:39:45 15:39 »

I don't know how similar the FY6600 and FY6800 models are, but there's a good site about the 6600 including replacing the oscillator here:

http://www.paulvdiyblogs.net/2019/09/upgrading-tuning-my-fy6600-waveform.html
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PM3295
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« Reply #3 on: December 27, 2019, 04:35:42 16:35 »

That looks like a much easier way to do the replacement. I did a similar thing in one of my Lecroy scopes, which used an 20 MHz TCXO. It bugged me that the time and frequency-related  measurements were not that good. I found a small Connor Winfield 20 MHz OCXO on eBay to replace it with. It made a great improvement in frequency and jitter measurements.
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Old_but_Alive
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« Reply #4 on: December 27, 2019, 04:49:41 16:49 »

did a google, dont have any details though :-

https://www.ebay.co.uk/i/381746763026?chn=ps&norover=1&mkevt=1&mkrid=710-134428-41853-0&mkcid=2&itemid=381746763026&targetid=523159728897&device=c&mktype=pla&googleloc=9046498&poi=&campaignid=6744139827&mkgroupid=78343140366&rlsatarget=pla-523159728897&abcId=1139126&merchantid=9702494&gclid=EAIaIQobChMIpea456PW5gIVycjeCh1yUwXvEAYYBCABEgKVn_D_BwE

this one looks more suitable, less than $20, since the TXCO is 25MHz, it is obviously frequeny doubling using the external IC, so dont know what the jitter would be. With all things Chinese, dont believe what they say !!

https://www.ebay.co.uk/i/113741015374?chn=ps&norover=1&mkevt=1&mkrid=710-134428-41853-0&mkcid=2&itemid=113741015374&targetid=540657990661&device=c&mktype=pla&googleloc=9046498&poi=&campaignid=1669190333&mkgroupid=67214010920&rlsatarget=pla-540657990661&abcId=578896&merchantid=6995734&gclid=EAIaIQobChMIpea456PW5gIVycjeCh1yUwXvEAYYByABEgLltfD_BwE
« Last Edit: December 27, 2019, 05:12:50 17:12 by Old_but_Alive » Logged

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Old_but_Alive
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« Reply #5 on: December 28, 2019, 09:48:02 09:48 »

more info


$14

https://www.aliexpress.com/item/32702145773.html?spm=2114.search0306.3.195.6ddd7131wbrPI5&ws_ab_test=searchweb0_0,searchweb201602_0,searchweb201603_0,ppcSwitch_0&algo_pvid=63689220-87af-4777-82fe-2fe65e7d8a08&algo_expid=63689220-87af-4777-82fe-2fe65e7d8a08-27


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I fought Ohm's Law ...  and the law won
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bobcat1
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« Reply #6 on: December 29, 2019, 03:48:38 15:48 »

Hi
If you want to do it yourself -> In the last issue of EPE there is a circuit design for OCXO made from discrete components for stabilizing a clock signal , you can build this circuit and replace the main oscillator , but since it need programming you will need to add small controller to control the synthesizer.

All the best

Bobi 
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hef4015
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« Reply #7 on: January 23, 2021, 12:10:20 12:10 »

Stable and accurate clocks can be also achieved with GPS disciplined clock generators.  Cool It is a bit more expensive  Sad and an antenna is required.  Smiley
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kukumar
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« Reply #8 on: March 15, 2021, 10:21:27 22:21 »

I have finished my dds generator (change reference)
It works ok.
I put TCXO (0,1 ppm) , add buffer to it , and it work perfect.
If , there is interest I will show my documentation?
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kreutz
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« Reply #9 on: March 17, 2021, 03:46:59 15:46 »

Please, show it.
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hef4015
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« Reply #10 on: April 07, 2021, 05:42:43 05:42 »

Please tell us what you did. Thank you.
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Unhappy
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« Reply #11 on: April 07, 2021, 07:54:55 07:54 »

I have finished my dds generator (change reference)
It works ok.
I put TCXO (0,1 ppm) , add buffer to it , and it work perfect.
If , there is interest I will show my documentation?

Kindly show the documents and prototypes you made
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