[time-nuts] Re: DOXCO from Z3801

[Andy Talbot]

> I've been given a defunct Z3801 with a fully working ovened oscillator.
> The rest of the GPSDO circuitry is just junk and will be chucked, but I
> want to get the DOXCO running as a backup high stability reference here.
>
> I've worked out the power connections for the oscillator and inner oven,
> and have powered it up with +12V & +24V supplies.   It's currently just
> warmed up and is happily generating a nice sine at 10MHz, with +0.3V (at
> the moment) t on the EFC.
>
> I applied 24V to the outer oven earlier to see what happened, and measured
> the thermistor resistance as it warmed, watching it fall from 110kΩat room
> temp to 30kΩ where I stopped.  I know the controller for the outer oven is
> in external circuitry, but a brief web search failed to show a) what
> temperature it should run at, To, and b) what the thermistor resistance
> would be at that temperature, Ro.
>
> Does anyone here know these figures off hand, or do I need to go to the
> web and download the circuit and trace out the outer oven controller
> details.   I'll be doing my own controller circuitry, so just need To and
> Ro.
>
> Andy
> www.g4jnt.com
>
>