I have been able to find schematics of the 10544A but not a service manual. Is there a service manual available?
Joe -----Original Message----- From: [email protected] [mailto:[email protected]]on Behalf Of Bruce Griffiths Sent: Saturday, March 07, 2009 3:24 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] About HP10544A Esa Heikkinen wrote: >> New 10544A's have a somewhat cleaner output than that. >> Perhaps something is wrong with the emitter follower. >> > > Sorry I forgot to say that the oscilloscope picture was taken directly > from HP10544A output, without emitter follower but with 1:1 probe, > output terminated with 1 kohm. resistor. With spectrum analyzer the > emitter follower is necessary due to 50 ohm. input impedance of the > analyzer. > > Datasheet of HP10544A claims that harmonics should be more than 25 dB > down. Doesn't look like they are. > > Here's a spectrum measured from OCXO which is used in the Thunderbolt. > I'm not an crystal oscillator guru but I think that this is just what an > xtal oscillator output should be: > > http://www.amigazone.fi/files/gpsdo/tbolt-1.png > http://www.amigazone.fi/files/gpsdo/tbolt-2.png > > Esa The capacitance of the 1x probe is too high. Use a 10x probe with 1k across its inputs at the 10544A. The 10544A output stage is an emitter follower. Bruce _______________________________________________ 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.
