There is a drop in freq for Pierce and Colpitt after 1 min of startup. Can
be 100Hz.
Serious enough.
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Not true.

100 Hz is a huge variation by crystal standards, especially in the lower
frequency ranges. If a crystal oscillator drifts substantially during
warmup, it usually implies two things:

1) The oscillator is driving the "so-called" parallel resonance of the
crystal, which is very dependent on circuit capacitance. I said "so-called"
because the parallel resonance isn't really a true resonance of the quartz,
it's a frequency where the crystal appears inductive enough to resonate the
combinationo fo the holder capacitance and the circuit capacitance.

2) The circuit is poorly designed.

BTW, some here have suggested just purchasing a 'can' oscillator. Be very
careful of these, and check the specs carefully. Many 'can' oscillators have
an internal programmable RC VCO that is PLL locked to a low frequency
crystal. The up-side is that the manufacturer will make any frequency you
want (some are even user-programmable). The down side is that RC VCO's have
horrible jitter ('phase noise') that isn't corrected by the PLL


Joe
W3JDR