The 21st century Hardy Boys adventure: The mystery of the DDS Modules

Try searching Ebay for:      AD9850 module

https://www.ebay.com/sch/i.html?kw=ad9850%20module

You will still get over 100 results, but the prices !  Yes, they used to be MUCH cheaper.  Here is one I purchased for $8.53 including shipping in 2014:

a module from 2014

There is also another version, very similar:

from a current 2022 Ebay listing

Of course, it isn't a requirement that a module be used, here is a DDS signal generator using an AD9850 that I built a couple decades ago (I think):

I found the blue DDS module while checking through my junkbox - now I have to wonder:  

Why were these modules made ?  

Was there some kind of massive project somewhere that required zillions of DDS modules ?  

 Because even at current Ebay module prices it would be hard to make ANY money selling these modules.  The AD9850 chip itself is still available, it sells for over $28 at Digikey:

Yes, I am still a stockholder in Analog Devices, one of the reasons why is that Analog Devices can get these kinds of prices for their chips.

And I suppose that the modules could have pirated, cheaper chips on board, but I really doubt that.  It would be a lot of effort for a very small-niche device.

Now ham radio people have mostly moved on from the DDS concept to the SI5351 PLL clock generator, I imagine the reason is those Analog Devices prices.

But if the Hardy boys were still kicking,  betcha they'd get to the bottom of the mystery of the DDS modules.

Best Regards,
Chuck, WB9KZY
http://wb9kzy.com/ham.htm