[time-nuts] OCXO Soft-Start
jimlux
jimlux at earthlink.net
Thu Apr 13 03:18:38 UTC 2017
On 4/12/17 7:14 PM, Richard (Rick) Karlquist wrote:
> 10.9 MHz is likely the B-mode of the SC cut.
> (It's a different mode, not a different overtone).
> This mode has a tempco of 20 ppm and is used
> to do thermometry.
>
> IMHO, there is NO excuse for the oscillator
> designer to design an oscillator that doesn't
> oscillate unconditionally in the right mode.
> NONE! What was the actual manufacturer of
> the OCXO? (AFAIK, Trimble doesn't make their
> own).
>
> My old boss at Zeta Labs (a really great boss)
> used to walk up to people who were testing
> their latest circuit and momentarily turn
> down the current limit on each of the power
> supplies to see if the circuit recovered
> correctly. It often didn't, and then it
> was back to the drawing board...
>
These days, a common trap is when you've got a DC/DC converter on the
input - with a soft start, the current goes huge, causing all kinds of
problems.
(I'm in the middle of closing a failure report on just such a
sensitivity - an unexpected interaction between the source DC/DC
converter and the load DC/DC converter..)
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