[minima] Re: AD9850 DDS Spurs
- From: Ashhar Farhan <farhanbox@xxxxxxxxx>
- To: minima@xxxxxxxxxxxxx
- Date: Thu, 23 Jan 2014 07:19:22 +0530
Steve,
here's one of the better write ups on the Si570.
http://www.cliftonlaboratories.com/si570_kit_from_k5bcq.htm
Though it is about a specific kit, it deals with the performance of the
Si570 very well.
I am going to open a new page on the Si570 on the wiki.
- f
On Thu, Jan 23, 2014 at 6:57 AM, Steve VK2SJA <vk2sja@xxxxxxxxxxx> wrote:
> Hi chaps,
>
> Spurred on (sorry, sad pun intended) by Rick LU9DA's problem in obtaining
> the Si570 in Argentina I've been doing some reading.
>
> Here is Hans Summers write-up on the Si750 vs DDS feature set. Well worth
> a read:-
>
> http://www.hanssummers.com/ddssi570.html
>
> Analog Devices have an online software design tool that you can use to
> model the output of their various DDS chips. Which obviously I'm not
> driving correctly. Because I'm seeing pretty pictures that look a whole
> lot cleaner than real world Amateurs are reporting ;-) I think the trick
> might be to click the link option "View Tabular Display of Spurs". But if
> one could learn to drive this tool properly and trust the predictions it
> looks like it could be useful:-
>
> http://designtools.analog.com/dtDDSWeb/dtDDSMain.aspx
>
> Gérard F6EHJ, has done some work with DDS and has some details and a
> pretty picture of a AD9850's (80Mhz version) output at 32Mhz. Actually,
> it's not particularly pretty.
>
> http://www.f6blk.net/main_en.php?page=77
>
> My impression is that you might be able to use a DDS for this application
> but that it would have to be at least a AD9851 or preferably better to get
> anything like reasonable results. I suspect that the really cheap Chinese
> AD9850 module just isn't going to cut it. And once you buy a DDS chip that
> will cut the mustard it is going to cost more than the Si570 anyway.
>
> Still, doesn't hurt to experiment and the software is the easy part.
>
> Sad really. Because I've got a box full of them too!
>
> 73, Steve
>
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