[time-nuts] About HP10544A

Esa Heikkinen scifiscifi at sci.fi
Sat Mar 7 17:58:14 UTC 2009


I got one of the 544's and plan to use it for rubidium cleaning loop 
(Efratom LPRO). But I cannot get a clean 10 MHz signal out from it! 
There are harmonics and spurious. I know that spurious come from oven 
swicther so those should be easily handled with separate oven supply.

But the bigger problem are the harmonics:

This spectrum is measured with emitter follower buffer connected to 
output which is terminated with 1k like datasheet recommends. So the 
load should be ideal but still distorted. The distortion can be seen 
even with oscilloscope:

So it ooks like negative half cycle is distorted.

As a reference, THIS is the signal to be cleaned with HP10544A:


So... I believe that there may be something wrong with HP10544A if it's 
output is worse than lower grade xtal oscillators used in LPRO etc.

But just to make sure I'm asking you guys having these oscillators. 
Should it even give clean sine wave or not? And if it should, where 
should I start to seek the fault?


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