[time-nuts] (no subject)

Ulrich Bangert df6jb at ulrich-bangert.de
Tue Sep 13 10:28:30 EDT 2005

Hi Folks,

i own a Efratom FRK-L which started into making trouble since the last
time i switched it on. I monitor the "lamp voltage" as well as the VCXO
control voltage. The unit locks a few minutes after power up. But then
the VCXO voltage is kind of "noisy" and unstable. While it formerly came
to a very stable value with changes only in the microvolt region after
some hours of warming up, now the VCXO control voltage jumps around in a
50 mV peak to peak region and sometimes it would even loose lock at all.

The "lamp voltage" is close to 7.00 V and very stable, so i do not
expect it to be a physical package failure. When i monitor the output
frequency, this seems to be indeed stable up to my counter resolution of
1E-9 @ 1s. From that i induce that the servo electronics in the FRK-L is
working ok and that it is indeed trying to correct for some VCXO

The big question however is: What makes the VCXO which has been working
very stable for years go in such a instable behaviour from one day to
another? Has anyone of you seen a behaviour like this with a FRK-L? What
way should i go for a deeper diagnosis: Oscillator electronics or
chrystal heater electronics? 

Best regards and thanks in advance for any help.  

Ulrich Bangert
df6jb at ulrich-bangert.de

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