[time-nuts] OXCO Issues
eb at telight.com
Sat May 11 10:42:59 EDT 2013
Why not just run it from a separate, regulated supply? Until you
check it with solid voltage applied, you won't know for sure - maybe
the OCXO is OK, but the oven circuit can't handle too high an
impedance from the supply.
At low frequencies, the OC part may exhibit negative resistance,
making an oscillator under some conditions. To see how this can
happen, picture the unit operating in static environmental
conditions. After warmup, the whole thing should take constant power
- on average - to maintain the XO temperature. If the supply voltage
increases, the current must decrease in order for the power to stay
the same - again, on average, over some time frame. This is negative
resistance, which can provide power gain to form an oscillator.
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