[time-nuts] Fury - Rubidium

SAIDJACK at aol.com SAIDJACK at aol.com
Tue Jul 27 21:48:09 EDT 2010


Hi Brian,
 
based on your measurements, it seems that your unit has a swing  of about 
0.00566 Hertz per Volt EFC, which is very little.
 
This compares to about 8Hz per volt for the standard DOCXO's we use.
 
That's a 1413 to 1 difference in EFC sensitivity between the Rb and the  
standard OCXO.
 
We use a dacgain of 15 for the standard OCXO, so try 15 * 1400 = 21,000 for 
 the Dacgain (that's a lot of dacgain!)
 
We use 0.7 for EFCS, and 15 for PHASECO, and 40 to 80 for EFC  Damping.
 
Unfortunately we do not have the Rb's here in house that you are using to  
try this out.
 
Let me know if that works,
bye,
Said
 
 
 
 
 
 
 
In a message dated 7/27/2010 17:46:42 Pacific Daylight Time,  
kilodelta4foxmike at gmail.com writes:

I did  another test and the rubidium dial setting was 000 for a control 
voltage  of 0.068V and the average frequency was 9 999 999.9933 hertz. 
The dial  setting was changed to 721 for a control voltage of 4.9999V and 
the  average frequency was 10 000 000.0216 hertz

The measurements were taken  with a HP5370B time interval counter 
referenced to a HP5065A rubidium  oscillator.  The data was recorded 
using a ProLogix GPIB  adapter.  The data was recorded in 10 minute 
intervals with the data  coming in at one measurement a second.  When the 
frequency was  changed, I allowed 20 minutes between the recordings.

Based on the  above measurements, Said, can you recommend some starting 
point for the  DAC Gain, EFC Scale, and the EFC Damping  ?



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