Bruce, I have seen this specs before but do you know how to find the schematics?
Best regards Ulric Bangert > -----Ursprüngliche Nachricht----- > Von: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] Im Auftrag von Dr Bruce Griffiths > Gesendet: Sonntag, 4. Februar 2007 08:32 > An: Discussion of precise time and frequency measurement > Betreff: Re: [time-nuts] Stepping up the output of an OCXO > > > John Ackermann N8UR wrote: > > I had a chance to measure a TADD-1 using an HP-3048 phase > noise system > > last year. I've attached a screen shot of the results; in short it > > was below -140dBc/Hz from 100 Hz on out (by the way, I'm not sure I > > would trust the noise floor shown in this test; I am not certain we > > had the best test set-up). That's within a few dB of what HP said > > their 5087A amplifier would do. > > > > I'll soon have access to a new phase noise measurement > system and will > > relook at the TADD-1 performance with it. > > > > John > > > > > John > > My calculations using the component values in the circuit > indicate that > the TADD-1 noise figure should be about 19dB and its > corresponding phase > noise floor should be lower than -160dBc/Hz. when the input signal is > +7dBm or greater. So unless you had an unusually noisy set of opamps > and/or resistors the measurement setup phase noise floor probably > exceeds that of the TADD-1 by around 20dB. > > With a 10V supply instead of 9V and a +13dBm input the phase > noise floor > should be about -168dBc/Hz which is respectable but a few > (~10) dB shy > of the state of the art. > > The only way to achieve the state of the art performance with opamps > using a 9 or 10V supply is to use lower noise (2nV/rtHz appears > feasible) opamps pairs driven in push pull by an input step up (1:2 > turns ratio) transformer with an output stepdown transformer > driven in > pushpull by the 2 opamp outputs. The noisy 1K input > protection resistor > would also have to be reduced in value as would the opamp feedback > network resistors. > > NIST's 1995 distribution amplifier claims a phase tempco of > 0.3ps/K and > 120dB isolation between channels. > http://www.physics.nist.gov/News/Update/950626> .html > > Bruce > > > > _______________________________________________ > time-nuts mailing list > [email protected] > https://www.febo.com/cgi-> bin/mailman/listinfo/time-nuts > _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
