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Posted by: Sam AE4GX Posted On: 09/15/01 Subject: Rather than a SCAF let your brain do the work! Message Posted: In Reply to: I am thinking about adding a SCF IC of MAXIM Co. posted by Adam/BD6CR on 09/09/01 One thing I have noticed on all my DC receivers (PIXIE , HW-8, Vectronics)is that the audio is very clean and clear. My ears aren't too good but when the signals are crisp and clean your brain seems to be able to filter the desired signal even though you might be hearing many signals within the audio spectrum at the same time. The brain has amazing ability at the lower AF Hz signals < 500-700 Hz. That's the advantage of VXOing the xtal is to get a lower CW tone so the brain can become the "active" filter. You don't stand much of a chance at the lower tone frequencies. So I think the key is getting freq. selectivity at the front-end with BP or notch filters to eliminate the CRUD from out of band singals and letting your brain be the AF filteron the real signals remaining. I definitely would try it before adding anything extra to the PIXIE. I did add a two stage op amp active filter to my unit but on hindsight I don't think it was worth the effort. Sam AE4GX |
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