[time-nuts] Rapco 1804M manual and Control Mode Access ?

[Peter Vince]

Where I worked we had a few of a later model Rapco 1804 (1804 L26 D2) which
had an LPRO Rubidium inside, and gave out 10MHz.  That had an eight-channel
Trimble receiver, but I'm afraid I can't remember the model number.

I wasn't very impressed by the disciplining algorithm which, once it had
settled down, just seemed to average the readings for 8000 seconds, and
then apply a step-change to the ruby's EFC.  This often resulted in
frequency jumps of several parts in 10^11 :-(

As stated in the manual that was linked, it was possible to disable the
automatic disciplining by issuing the RL command to "lock" the EFC.  It was
then possible to steer the EFC externally - the RV command reading the
current value, and the @V command changing it.  Said EFC was driven by a
16-bit DAC, which gave an average frequency-step size of about 6.7 E^-14.

Regards,

     Peter