[time-nuts] OXCO Issues

ed breya 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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