From: Dr Bruce Griffiths <[EMAIL PROTECTED]> Subject: Re: [time-nuts] Stepping up the output of an OCXO Date: Mon, 05 Feb 2007 01:22:54 +1300 Message-ID: <[EMAIL PROTECTED]>
> Ulrich Bangert wrote: > > Bruce, > > > > I have seen this specs before but do you know how to find the > > schematics? > > > > Best regards > > Ulric Bangert > > > > > Ulrich > > Since the earlier NBS isolation/distribution amplifiers consisted of dc > coupled cascaded common base stages (according to Magnus who had looked > at some), One of the NBS/NIST articles is "Design Considerations in State-of-the-Art Signal Processing and Phase Noise Measurement Systems" by F.L. Walls, S.R. Stein, J.E. Gray, and D.J. Glaze: http://tf.nist.gov/timefreq/general/pdf/90.pdf See Fig 1 for the amp that I was talking about. Look - no coils! I actually wander if they have not made a point of building it off 3 2N3904 rather than some more suitable transistor. I've seen similar stuff from these culprits before. > the newer generation developed in conjunction with the > technical university of Torino may merely use the same topology with > faster transistors (SiGe??) perhaps in IC or hybrid form. Why not? ;O) > I suspect that the 0.3ps/K may have been a typo and they use amplifiers > similar to the Spectradynamics Distribution amplifiers rated at 3ps/K. > These distribution amplifiers are recommended by the BIPM. > For the 1-20MHz amplifier see: > http://www.spectradynamics.com/HPDA-15.html > See attached files for phase noise plot and mechanical shielding used. > > I guess there's a passive splitter in there somewhere and a bandpass > filter (which probably contributes most of the phase tempco) in there as > well. Indeed. Probably an initial boost, passive splitter and iso-amps. Cheers, Magnus _______________________________________________ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts