Just FYI, this current batch of FE-5680As has a different RF architecture than the old ones - one of the most notable changes is that although they still have a DDS in them it's not in the output path anymore - the VCXO now runs at 60MHz, and this is divided down (in a CPLD) to produce the 10MHz output - so it's likely that your output measurements are not really applicable to these units.
On Fri, Dec 30, 2011 at 2:37 AM, Said Jackson <saidj...@aol.com> wrote: > Hello Mike, > > We measured a couple of these 5680As on a tsc5125a analyzer. With different > quality supplies. > > Very noisy buggers, huge number of spurs and very high noise floor -130dBc or > so if I recall correctly. Thats probably the jitter you are seeing. Probably > due to the dds generating the output not a crystal. > > ADEV was parts in E-011 while good, not very good. > > Frequency accuracy was +5E-010 then tap the box hard and it goes to -1ppb. > > Good enough as a portable frequency counter reference, as the offset can be > compensated, and the output is fairly stable... > > These units could really use gps disciplining and a crystal post filter. > > Great stuff for $40, new they must have been over $1000. > > Bye, > Said > > > > > > > > > > On Dec 29, 2011, at 1:14, mike cook <michael.c...@sfr.fr> wrote: > >> Hi, >> Just got my cheapo 5680A. It was accompanied by a little teddy bear >> clutching a L7805CV ! >> >> Got a couple of questions. >> >> 1) What is the expected 10MHz peak to peak voltage. FEI doc seems to >> indicate 0,5V but I am getting only 200mv. >> 2) What is the sensitivity to 15V input level. I am only measuring 14,722 >> (stable) on Pin1. >> 3) Could this low input voltage affect output voltage? >> >> The box locks after a couple of minutes but my TDS 210 is showing a very >> jittery ( 9,98-10,02 MHz ) but well formed sine wave for 8 hours of being >> powered on. Could this also be an artefact of low main power? >> >> rega >> Mike >> >> _______________________________________________ >> 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. > > _______________________________________________ > 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. _______________________________________________ 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.