A DDS chip on its own may cost more than 30...40 dollars, unless the
manufacturer is willing to send you a sample. And what is wrong with AD 995X
series DDS? They are of a very low "spectral grass". You can also get an
idea for how much AD sells their DDS evaluation boards by browsing their
product catalog.

wrote in message
oups.com...
I have the following question regarding DDS chips:

The amqrp website and others detail techniques for using Analog
Devices', DDS chip as an accurate digitally controller oscillator. One
of the issues that needs to be bourne in mind according to the articles
is the spectral purity of this chip's output. There seem to be various
schemes using PLL and filtering to kill the harmonics and spectral
"grass" that these things seem to generate. Given the onward march of
technology, is there any chip similar to the Analog Devices DDS, that
would give be a spectrally pure, low noise sinusoid with any further
filtering or PLL? I'd like something good enough to be a high quality
VFO for an HF receiver (I and Q available)?? Is such a thing
available, preferably offering a presoldered evaluation board (I don't
want to go blind soldering it!!) for 30 or 40 bucks kind of price
range??

Thanks,

Tim