[time-nuts] Z3801A OCXO manual trimming

Bob kb8tq kb8tq at n1k.org
Tue Mar 6 09:35:29 EST 2018


Hi

The control range should be +/- 5V if I remember correctly. If it’s not, the
only other standard would be 0-5V. There is zero logic in running a wider
swing mod to an OCXO at a lower EFC range. 

It indeed sounds like the DAC has trouble. 

Bob

> On Mar 6, 2018, at 1:24 AM, Mark Sims <holrum at hotmail.com> wrote:
> 
> I'm not sure what the Z3801A uses for EFC range.   Heather uses the EFC relative command to report the EFC setting.  That command reports values from -100% to 100%.   There is a command that reports the DAC input in counts, but nothing documented that shows volts/count.
> 
> Since the DAC is at -2V with a 99+% DAC setting, it looks like the DAC circuit has issues, or power supply problems.   I think the DAC circuit is a 16 bit DAC with 4 more bits of resolution created by dithering the DAC inputs.
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