At 04:19 PM 10/21/2007, Rob Dennison wrote: >Hi guys, > >Have my SDR1k working well enough now to start tackling deeper problems. > >One of the first is the 11kHz DC noise. Quite a few of my friends have >been through the shack now. They always ask about the 11kHz hump and are >always turned off by my Q10241 answer: "gotta live with it." It is a >real problem in selling them on flexRadio. They look on it as a design >defect. So do I. > >So having read and re-read Q10241 in the knowledge base I am still >dissatisfied. Why do we have to live with it? It is a design defect. > >1. Okay on audio transformers but why not optical isolation? It seems >optical isolators would have much wider bandwidth.
Transformers are easier.. all passive devices for one thing, and they've had decades to make very linear transformers with good bandwidth. Optos require some power supply, have to deal with the issue of putting a DC bias on the sending end, etc. All solvable, but it takes more parts. Capacitive coupling is yet another galvanic isolation approach. And, there are some very cool parts from Analog Devices to do this. But, all in all, transformers are easy. Jim, W6RMK _______________________________________________ FlexRadio mailing list [email protected] http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archive Link: http://www.mail-archive.com/flexradio%40flex-radio.biz/ FlexRadio Knowledge Base: http://kb.flex-radio.com/ FlexRadio Homepage: http://www.flex-radio.com/
