Hi Tossing a beach towel over it usually does a pretty good job out to 10 seconds.
Bob -----Original Message----- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Bruce Griffiths Sent: Tuesday, April 17, 2012 8:46 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Opamp Phase noise: OPA653 additional measurements I'll try shielding from air currents (usually effective to a little below 1Hz). The Opamp is thermally connected (metal tab under package is soldered to) to one of the power planes so the thermal time constant is a little longer than it would otherwise be. Bruce Bob Camp wrote: > Hi > > My *guess* is that your 1Hz data may be as much from ambient changes as from the op amps themselves. No data to back that up on these specific parts, just a guess. > > Bob > > On Apr 17, 2012, at 7:28 AM, Bruce Griffiths wrote: > > >> Not yet, I just used the pair of TI evaluation boards which I obtained for another project. >> >> I intend to mount the various components (splitters, 180 degree hybrids etc) on a thick aluminium plate to improve the mechanical and thermal stability of the system. >> >> Bruce >> >> Bob Camp wrote: >> >>> Hi >>> >>> Did you do any temperature stabilization on the op amps? >>> >>> Bob >>> >>> On Apr 17, 2012, at 5:25 AM, Bruce Griffiths wrote: >>> >>> >>> >>>> Subsequent measurements using an improved technique has allowed the true flicker phase noise characteristics of a pair of OPA653 opamps to be determined. >>>> >>>> Opamp >>>> Gain 1x (6db folled by 6 db attenuator consisting of a 50 ohm resistor in series with the output of the opamp and the 50 ohm load resistor) >>>> Signal input level: + 10dBm >>>> >>>> OFFSET Opamp PN (dBc/Hz) Measurement system PN (dBc/Hz) >>>> >>>> 1 -148 -161 >>>> >>>> 10 -161 -172 >>>> >>>> 100 -164 -177 >>>> >>>> 1000 -164 -179 >>>> >>>> Source: 10MHz low phase noise OCXO removed from a Thunderbolt amplified by a QBH9816 amplifier. >>>> >>>> Conclusion: FET opamp PN in the flicker region can be quite low despite its somewhat higher baseband flicker noise than that of some bipolar input opamps. >>>> >>>> Bruce >>>> >>>> _______________________________________________ >>>> 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. >> > > _______________________________________________ > 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.