[time-nuts] time-nuts Digest, Vol 65, Issue 112

[Mark Sims]

The HP 10811A (generally regarded as a pretty good oscillator) has a spec of 4.5E-9 over 70C which is 6.4E-11/C.   If I'm reading my notes correctly,  that tbolt oscillator measured at 1.4732E-10 parts/C...  about 2.3 times worse than a 10811A.

Generally Thunderbolt oscillators have rather crappy tempcos.   There has been a lot of talk about them being double oven units,  but I seriously doubt that.   They make pretty good T to F converters...  

Note that some of the tempco could be due to the power supply,  it is outside of the temperature controlled box.  A previous test indicated that about 1/3 of the tempco was due to power supply variations)

Those temperature cycles in the graph are +/- 10 millidegrees...  the oscillator should be moving 3 parts/trillion over the cycle (assuming no thermal lag).  Such a small change shows up very clearly in the self-reported OSC error data from the Thunderbolt.


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The oscillator tempco shown on the screen is -1.6 ppb per degree C. 1/10 of that would be 0.16 ppb/C.  I would hope that the oscillator in your Thunderbolt is much better than that.

 		 	   		  
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