Do you guys think this is worth building and does it have good enough accuracy??
Do you guys think this is worth building and does it have good enough accuracy??
Well 'good enough' is not a useful unit of measurement.
However I built a similar device using the AD9850 used as the VFO LO for a ham 7MHz CW receiver. Worked great, heard no distortion, and very stable frequency control. I amplified the output using a MMIC chip to drive a double balanced diode mixer. So lots of capability for very little $, what's not to love?
The AD9850 good for me 
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NewFile6.jpg
congratulation for reading the signal in average mode...
The AD9850 good for me .
NewFile6.jpg
congratulation for reading the signal in average mode...
Harsh? Why not explain what is wrong and why that may not be the best setting? Us newbies might benefit more from that.
I did get a much cleaner reading on mine by swapping out the ground lead to the spring. There was another thread talking about this. Thanks to whomever posted that! (I wish I saved the link.)
Harsh? Why not explain what is wrong
no i'm trying to be gentle actually, since most newcomers will get hot when told the truth and they will come with their machine gun theory book. look, my AD9850...
picture 1) very nice!
picture 2) so so
picture 3) well?
bear in mind this is sampled 25 points per cycle (40MHz @ 1GSps)
picture 4) how a theoritical 25pts sine should looks like.
conclusion: "average" will closely resemble perfect sine. "single capture" (picture 3) is the truth. if we want talk sweet and sugar, we show "average", if we want to talk the truth grain and salt, show "single capture", "average" is nice, but not truth. and lastly... use 1X attenuation 50 ohm Z coax with 50 ohm termination at the scope end when testing, thats the de-facto standard way... google it its too long, fwiw..
picture 5) when superimposed theory and the truth... fwiw..
and lastly... use 1X attenuation 50 ohm Z coax with 50 ohm termination at the scope end when testing, thats the de-facto standard way... google it its too long, fwiw..
Googling that now. Thanks! As you can see from the pics I posted, I took a single instead of the OP's average. Also I was just probing directly on the board with no termination.
I'm putting it into an antenna analyzer right now so we'll see what it looks like when it is seeing 50 ohms.