[time-nuts] Re: DOXCO from Z3801

[paul swed]

Andy
For what you are doing I am not sure the outer ovens really needed. Its use
would have been for locations like Cel Towers and such that can be very
poorly heated if at all. I might guess you could put a temp probe in and
set it at some temp like 100 F and let it go. Or as I say not use it at all.
Others will have stronger opinions.
Regards
Paul
WB8TSL

On Wed, Dec 7, 2022 at 5:28 AM Andy Talbot via time-nuts <
time-nuts at lists.febo.com> wrote:

> > 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
> >
> >
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