[time-nuts] FE-5680 frequency jump
Magnus Danielson
magnus at rubidium.dyndns.org
Mon Apr 1 21:57:48 UTC 2013
Hi Bob,
On 04/01/2013 10:06 PM, Bob Quenelle wrote:
> I’ve been running an FE-5680 for maybe a total of 50 hours over the last several months. I found that an offset setting of 180 made it track GPS and (previously-set) LPRO-101 10 MHz signals. Even with power cycling, after about 1/2 hour, with an offset setting of 180 the FE-5680 was stable. The last time I turned on the FE-5680, it drifted with a setting of 180 and needed a new setting of –415 to track the other signals. That’s a change of 595 counts and with a resolution of 6.8 uHz per count, a frequency change of 4 mHz (0.004 Hz) and 0.4 ppb. Operation at the new setting is stable for now. The lock signal indicates lock and the power supply voltage is still 15V. I haven’t checked lamp voltage or VCXO voltage as that requires opening the case.
>
> Before I start poking around, thought I’d ask if anyone has seen a similar symptom. Time to open it up?
How long have it been turned on since last power-up?
Let it sit for a day at least.
I've found that it is easy to be in too much hurry to judge the
situation and trim things efter power-up. The crystal oscillator just
doesn't get the time to settle in.
When triming up caesiums, I did this mistake myself, altered my ways and
got a much better result.
Cheers,
Magnus
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