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Electronics => Hardware and Tools => Topic started by: kukumar on December 27, 2019, 01:17:18 13:17



Title: DDS Signal Generator
Post by: kukumar 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?


Title: Re: DDS Signal Generator
Post by: PM3295 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 (https://www.minicircuits.com/WebStore/dashboard.html?model=RK-3%2B)


Title: Re: DDS Signal Generator
Post by: Magnox 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


Title: Re: DDS Signal Generator
Post by: PM3295 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.


Title: Re: DDS Signal Generator
Post by: Old_but_Alive 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


Title: Re: DDS Signal Generator
Post by: Old_but_Alive 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




Title: Re: DDS Signal Generator
Post by: bobcat1 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 


Title: Re: DDS Signal Generator
Post by: hef4015 on January 23, 2021, 12:10:20 12:10
Stable and accurate clocks can be also achieved with GPS disciplined clock generators.  8) It is a bit more expensive  :( and an antenna is required.  :)


Title: Re: DDS Signal Generator
Post by: kukumar 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?


Title: Re: DDS Signal Generator
Post by: kreutz on March 17, 2021, 03:46:59 15:46
Please, show it.


Title: Re: DDS Signal Generator
Post by: hef4015 on April 07, 2021, 05:42:43 05:42
Please tell us what you did. Thank you.


Title: Re: DDS Signal Generator
Post by: Unhappy 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