[time-nuts] 10811 outer oven controller.

[Tom Van Baak]

Hi Warren,

That's a really nice plot.

One comment about the 60:1 quote, though. The plot shows the improvement is only 4x when you look at the TI data (what you call "phase" noise). And the plot shows the improvement is only 1.25x when you look at the OSC data. Further, if you were to plot the actual output of the TBolt (instead of plotting internal PLL loop statistics) I think you'd find these ratios get even less impressive.

Thus the other way to interpret the plot is to say that in spite of the 60x difference an outer oven makes to the tempco of a stand-alone quartz oscillator, it falls to just 1.25x when used in a GPSDO. One could rightly conclude then that outer ovens just aren't that important to the stability of a locked GPSDO.

Two questions,

1) How did you calculate the two tempco values (1e-12, 6e-11)? From the plot or with other tests?

2) Was the time constant (800 s, 0.9 damping) optimized for outer oven turned on case? Was it re-optimized for the outer oven off case?

/tvb

----- Original Message ----- 
From: "WarrenS" <warrensjmail-one at yahoo.com>
To: "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
Sent: Friday, July 12, 2013 6:04 PM
Subject: Re: [time-nuts] 10811 outer oven controller.


> 
> Bob said {the 10811 will run fine without the outer oven}
> What I've seen is that a dual oven 10811 will run even **finer** and have up 
> to 100 times less sensitivity to normal room temperature changes with a 
> simple outer oven controller and a few mods.
> 
> In 2010 I compared the performance of a TBolt using an external dual oven 
> 10811 Osc with and without it's outer oven being controlled.
> There was more than a 60 to 1 improvement in the 10811's freq sensitivity to 
> small room temperature changes when the outer oven was active.
> Open loop 10811 TC was <1e-12 /C with the dual oven on compared to 6e-11/C 
> with it off.
> The green trace shows how much less EFC correction is needed to be to keep 
> the 10811's frequency constant when the dual oven is active.
> http://www.febo.com/pipermail/time-nuts/attachments/20100223/c94d5eec/attachment-0001.gif
> 
> ws
> 
> *************************
> ----- Original Message ----- 
> From: "Bob Camp"
> To: "Discussion of precise time and frequency measurement" 
> <time-nuts at febo.com>
> Sent: Friday, July 12, 2013 10:45 AM
> Subject: Re: [time-nuts] 10811 outer oven controller.
> 
> 
>>Hi
>>
>>The "outer oven" on that version is simply a warmup heater. If it's 
>>operating properly, it drops out in normal operation. Put another way - the 
>>10811 will run fine without it.
>>
>>Bob
>>
>>
> 
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