Getting the square wave out is easy - if you follow down the trace from that J8 socket (which is also connected to the output on the D-type) it goes to a cap - just remove that and solder a jumper across the pair of pads to the left of it (I.E. closer to the PLD).
Regards, Pete On Fri, Dec 9, 2011 at 9:32 PM, Javier Herrero <[email protected]> wrote: > Hello, > > Yes, I know that the phase noise is the spectrum analyzer one, but the > spurious that are around (mostly -70, -80dBc) are not, particularly the ones > at +/200kHz and +/-400kHz. I was mostly curious about the harmonics and > other spurii since in this unit, 10MHz are generated from a CPLD divider, > and this approach sometimes leds to strange spurious and nasty things > around, but in this case seems not bad. As far as I remember, in a FRS-C the > output is from a 10MHz crystal oscillator. > > And the harmonics, well... usually we square that output and they have not > importance, but sometimes it is desirable to have a clean as possible > signal, and I was curious to see how good (or bad) the filtering was :). On > other side, we can use square wave from the CPLD (not yet checked, but it > must be there inside, somewhere :) ). The 2nd harmonic is very low, that > indicates that square wave symmetry is very good. > > Regards, > > Javier, EA1CRB > > El 09/12/2011 14:10, Marco IK1ODO -2 escribió: > >> Javier, >> >> the plots are nice, and I did the same years ago for an Efratom FRS-C. >> Found about the same data. The only point is that with the spectrum analyzer >> you see the S/A pahse noise, not the Rb, wich has to be orders of magnitude >> lower. >> About the comments on the waveform and harmonics contents: who cares about >> having the 2nd harmonic at -30 or -50 dB? For any practical use one has to >> square the signal, and the original harmonic content is of no pratical >> interest, or I am missing something ... >> >> 73 - Marco IK1ODO / AI4YF >> >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> >> > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there.
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