Good evening, Bob - sorry for the delayed response HI!
I want to build my own SDR for the AM modes in the HF bands. (I'm a retired hardware/software hacker on a mediocre budget.)
My reading has suggested to me that direct conversion to baseband with quadrature outputs to my PC sound card is probably the best answer to the various engineering issues, at least for my first try. I have spent many hours looking for hardware prototyping components suitable for my limited abilities and 73 YO eyes.
What I think I am looking for is a DDS with baseband quadrature output. I can't seem to find such products except up in the cellular frequencies. I really don't want to have to upconvert to get the HF bands into a range where I might use an available DDS to bring the signal back down to baseband.
So, what are some of my other options? (I already have a Flex-5000 SDR for operating, but want to do something simple on my own bench.)
Thanks, any comments from you or anyone else wpould be most welcome.