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

[Bob Camp]

Hi

It's a pretty good bet that at 10 minutes the OCXO is still trying to stabilize from a temperature step. 

Do you know which oscillator your Tbolt has in it? There have been several different ones used over the years. Some are better than others ...

Bob

On Dec 28, 2009, at 1:45 PM, Mark Sims wrote:

> 
> 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.
> 
> 
> ------------------
> 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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