Sorry, forgot to set the topic in the first mail > -----Ursprüngliche Nachricht----- > Von: Ulrich Bangert [mailto:[EMAIL PROTECTED] > Gesendet: Dienstag, 13. September 2005 16:29 > An: Time nuts ([email protected]) > Betreff: > > > 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 instabilities. > > 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 > [EMAIL PROTECTED] >
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