[GPS_Standard] VE2ZAZ

[grahamh at austin.rr.com]

Dave:

You might want to pull a data sheet on the CERMET trimmer you
are using for course set.  The sample spec sheet I pulled shows
resistance tolerance of +/- 100 ppM per degree C !

Also review the voltage tolerance versus temperature of the
single chip regulators.  They are typically not good enough for controlling
a disciplined oscillator.  You may want to consider precision voltage
sources, rather than common single chip regulators.

Consider all voltage tolerances in terms of the frequency control sensitivity
of the device you are controlling.  You will find that you are dealing
with control voltages that need to be stable in the range of tens of microvolts
DC.

What you are fighting might not be the oscillator, but the design
of the course expander and control circuits you built.

--- Graham / KE9H