Huff&Puff encompasses a lot of circuit variations, I like to use the more advanced forms that look at more than one bit of variation. The simpler versions have the problem that the circuit is never happy and keeps toggling back and forth not happy with either choice of frequency.
The version I like is basically a PLL circuit but the phase comparator locks to any multiple of the reference frequency not at an exact one and only one frequency. The phase comparator is the only difference between it and a PLL. It tends to be smooth like a PLL in that it's not hunting for the frequency all the time like the one bit H&P do. As far as the transformer my plan was to put it on the output of the audio amplifiers for the purpose of totally isolating the radio from the sound card. I have not seen any clear explanation what it will do for you by putting it between the QSD switches and the input to the audio amplifiers that can't be achieved by changing the output windings of the transformer that feeds the QSD switches. At 05:04 PM 6/10/2006, you wrote: >--- In [email protected], KD5NWA <[EMAIL PROTECTED]> wrote: > > > > The Huff and Puff moves the frequency to correct for drift and that > > is the key. Careful design and construction of the VCO will give you > > low drift therefore not many corrections. > > >That is correct, but it seems that the output frequency will toggle >between 2 frequencies separated by the "resolution" of the Huff & Puff. >In any case the VCO must already be very stable. > >Regarding the audio transformers from one of your other posts: >would you place them AFTER the OPAs or BEFORE as suggested by JR Dakota? > >Jean-Claude PJ2BVU > > > > > > > > > >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/
