Re: [N2PK-VNA] DDS Comparison

[Giancarlo Moda <i7swx@xxxxxxxxx>]

this note has not much to do with Linrad, but I am
sure
you will find the final information quite interesting,
as additional knowledge each of us can gain.

A good friend of mine, Giuliano Carmignani, I0CG, has
developed a very interesting line of DDS. He has just
published some pictures of the assy and a Spectrum
Analyzer comparison between the DDS output using one
with AD9851 and one with the AD9951. 
You will see, on the two pictures, a bandwidth up to
50MHz. Clear is the lower amount of spurs generated by
the AD9951, going into the SA noise (-80dB). 

Certainly, many high performance applications may
require higher spurs attenuation. The comparison you
will see is still an important one, as there have
been, in the recent past, comments/enquiries on DDS
spurs.

The DDS I0CG has developed had a key study on the
problems associated with the printed circuit board
design to reduce spurs and phase noise.
This kind of DDS has been applied to upgrade old
commercial equipment like Drake, Collins, others and
also homebrew projects.

I0CG info is now on 3 mirror sites: one in Italy, one
in Denmark and one in USA.

Italy - http://www.radioamatore.it/i0cg/add9951.html

USA -
http://www.nitehawk.com/rasmit/vna_dds/ad951_dds.html

Denmark - (OZ6YM) - http://www.oz6frs.dk/

From the Italian site it is possible to download the
DDS Manual in .pdf.

73

Gian
I7SWX







		
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