[time-nuts] About HP10544A

Esa Heikkinen scifiscifi at sci.fi
Sat Mar 7 21:18:33 UTC 2009

> 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 

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:



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