On Wed, 18 Jan 2017 21:06:04 -0800, you wrote: >On 1/18/2017 6:34 PM, David wrote: > >> An alternative very simple design I might try is a variation of the >> active frequency multiplier where the 5th harmonic is filtered >> directly from the output of the digital divide by two stage. > >That's a useful trick to reduce the filtering burden. Having said >that, if you need good spectral purity, the filtering is still >going to be very non-trivial. The original poster is obviously >not an expert in filters and will not be successful trying that >approach, except for very low performance design. Even if >you are a filter expert, components are hard to get. > >Rick N6RK
I only suggested it because Loren seemed dead set on a harmonic frequency multiplier. The output from a digital logic gate will already have a strong 5th harmonic so no extra passive or active harmonic generating stage is needed. The document I linked discusses the filtering requirements like notching out the strong 3rd harmonic. If spectral purity is important, then this is the wrong way to go about it; it would be better to phase lock a separate crystal oscillator. In some applications I would also be concerned about the phase of a narrow bandpass filter changing with temperature. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
