Try it out on LTSpice, it's free and works quite well. < http://www.linear.com/company/software.jsp >
Modem transformer are typically 600 Ohms to 600 Ohms so it meets the telephone line specifications and their response is only flat to about 5KHz. That is why I was looking at the transformers that I pointed out, they are flat to 100KHz. If you have a specific sample that is good to about 90KHz post it to the list, there are several people that would be interested. Work out the math, you would want the MSD of the radio to be at least .3 uV it's going to need a lot of amplification so the sound card can detect it. The SoftRock V4, V5, and V6 run with an audio gain of 500X, V7 runs with a gain of 50X but it's not as sensitive as the others. At 03:42 PM 6/10/2006, you wrote: >KD5NWA > > On the transformer ideas there are two others I can think > of. Digi Key and Mouser sometimes list 96 kHz transformers or some > at 78 kHz or so. > > Next, the idea of using 600 ohm to 600 ohm (or 600 to 1200 ohms > or more) modem type transformers. These will have enough bandwidth > for 96 kHz. Some may have one of the windings at impedances higher > than 1200 ohms. And well, these are cheap alternatives. > > With an audio signal generator you may analyze placing capacitors > across one or both windings to tune the bandpass or shift the > transformers center frequency. You can adjust one of the windings > for a certain center and the other winding for another center > frequency and hence tailor and spread out the output. Using this > idea you can also make the transformer act like a passive but > switchable bandpass filter for wide or narrow bandpass. So there > is allot you can do with such ideas. > > Good audio transformers always give you certain options of > use. The tranformer can do more than just match impedances. It > can be switched into filter mode if you want to use it as such. > > I am thinking that if Mosfets are used to make the quadrature > detector section then the gain of such; may allow a mere > transformer after that as the intermediate stage between the > detector and the sound card without amplification? Only test will > tell for sure. That would be an interesting thing if it will work. > >ka9rza > > >_____________________________________________________________________ >Call Anyone, Anytime, Anywhere in the World - FREE! >Free Internet calling from NetZero Voice >Visit http://www.netzerovoice.com today! > > > > > > >Yahoo! Groups Links > > > > Cecil Bayona KD5NWA www.qrpradio.com "Windows the worlds most successful software virus" ------------------------ Yahoo! Groups Sponsor --------------------~--> Get to your groups with one click. Know instantly when new email arrives http://us.click.yahoo.com/.7bhrC/MGxNAA/yQLSAA/ELTolB/TM --------------------------------------------------------------------~-> Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/soft_radio/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
