[time-nuts] FRS-C TTL / sine outboard filter question
Leigh L. Klotz, Jr. WA5ZNU
Leigh at WA5ZNU.org
Wed Jun 23 20:44:37 UTC 2010
> If you need a sine wave output but don't want to change anything inside,
> just add a lowpass filter.
> A 5th order LPF (three inductors/ 2 caps or vice versa) should give you
> a clean sine wave output.
> Just add a coupling cap to remove the DC component.
Thank you, Adrian. I'll pursue both options, internal fixes and external
filter. A multi-pole LPF is easily understood, and I don't believe I care
about passband ripple, though I wonder a little about the effect of the
coupling on phase changes (i.e., does this have any unfortunate effect on
I still don't know if a crystal ladder filter will suppress the harmonics,
but I did get the answers that make me not need to ask anymore (1. fix the
internal filter, 2. use the high Q xtal filter for optional removal of
Given time I would do all of these things, but I may not get to them all!
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