Duh, buffering is a must but don't forget the metal screen separation with pass-through cap between the two stages. Solid ground shielding is the only real effective filter against counter's trashy spurs. OK, this is really obvious, but remembering this again doesn't damage any brain (as my grandfather used to say).
Andreas vy 73s de IK2WQI dcappels wrote: > Yes, this is probably the best solution. You would count on the loop > filter (no pun intended) to take out most of the spurs. Also, some > have noted that some buffering is required between the VCO and the > counter to keep noise from the counter chain from getting into the VCO. > > --- In [email protected], "sis108" <[EMAIL PROTECTED]> wrote: > >> I often wondered why you couldn't use a 1x VCO and phase detctor. >> >> IE DDS 50-60Mhz out VCO 50-60MHZ both phase detectors 50-60mhz in. >> Hopefully the loop filter would kill the spurs. >> >> I have not found high speed phase/freq detectors however. >> >> Anyone have an opinion on how well this might work to kill the spurs? >> >> >> --- In [email protected], KY1K <[EMAIL PROTECTED]> wrote: >> >>> Has any amateur ever done a DDS in conjunction with a PLL to clean up >>> spurs? I hear chatter about it working well if the PLL is designed >>> properly, but have never run across any real life examples of the 2 >>> technologies rolled into one. >>> >>> I understand the DDS has advantages, especially in it's ability to >>> change frequency quickly. But, if rapid qsy's are not needed, I would >>> think a PLL with a slow response time in the filter would be as good >>> or better with respect to spectral purity than any DDS available >>> > today. > >>> Appreciate any pointers to web resources discussing this topic. >>> >>> Thanks, >>> >>> >>> Art >>> >>> 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/
