[time-nuts] E1938A oscillator pinning

SAIDJACK at aol.com SAIDJACK at aol.com
Mon Aug 27 20:13:28 EDT 2007

Hi Bruce,
I got it to work, it even locks to -5Hz within 5 minutes and the Amber LED  
goes off.
The problem was that I had only applied GND to the shield of the connector.  
I added a wire to the EFC pin to EFC return, and connected the three GND pins 
of  the connector, and magically it started working.

Seems one of those "GND" pins is actually a "heater on" type of  pin.
Now I will do some experiments, it seems EFC should be 2.5V for the output  
to be on frequency (not 0V).

Another interesting observation: my unit has 2.532V on the reference  output. 
I could probably try to locate the reference, and replace it with  something 
more modern and stable.
Lastly, the unit seems to have a slow 2-4 second sinusoidial drift in parts  
to the -11 when measuring it's output on my 53132A after about 10 minutes  
warmup. Wonder if that's the oven heater control loop...

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