I bought a random cheap crystal oscillator off AliX. It was advertised as a “constant temperature crystal reference”.
I also didn’t know what voltage it took. I found a photo of a similar one which apparently needed 12 V. However, smoke started coming out when I tried 12 V.
It seems to oscillate OK on 5 V though. However, it seems to be fluctuating in frequency, and I don’t know if this is normal, or whether I have damaged it.
Assuming that this is a 10MHz reference, at the extreme your reference is 0.003Hz off from nominal (3e-10, or 0.3ppb error). It varies by 0.08ppb in the plot. IDK what it is that you bought (TCXO, OCXO, whatever), but that’s rather impressive stability. Depending on what type of oscillator it is you can expect a temperature coefficient anywhere in the several ppm to 0.1ppb. Do you know by how much the ambient temperature (or even better, the oscillator temperature) changed over the duration of the plot? I don’t work with temperature-compensated oscillators very often, but I don’t see an issue here.
i assume its measured under laboratory conditions, so it seems ok to me. TCXO, OCXO should usually be operated within their operating voltage range. depends on type. usually i would assume 1.8-3.3v, but who knows without datasheet?
