Hal Murray wrote: > > [email protected] said: >> No it doesn't use a cheap crystal. It uses a *special* SC cut crystal. >> This >> crystal could very easily cost more than an OCXO crystal. > > What's special about it?
First, it has to have no activity dips over the full operating temperature range. OCXO crystals only have to work at the oven temperature. Activity dips, according to John Vig, are the reason whey they don't use mode B to sense temperature. Second, it has to be cut correctly so that the beat note between the fundamental times 3 and 3rd overtone modes is a useful indicator of temperature. > > I assume the cost-more aspect would be to allow an overall goodness factor > competitive with an OCXO in the low power corner of the marketplace. It > might be cheaper overall to use a good crystal and a uP to correct for > temperature than provide the power to run the oven. Again, the MCXO is not a poor man's OCXO. It tends to be used in applications such as manpack radios where battery constraints rule out ovens, regardless of cost. > > -------- > > The other area where a uP is useful is in an environment with high > vibration. It can correct for acceleration as well as temperature. There I've never heard of this being done. Do you have a reference? Rick Karlquist N6RK _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
