> Interestingly, if I remember correctly, Scott described at one time on the
> reflector that the TCXO did not have better stability than the earlier
> crystal oven. They moved to the TCXO because the ovens were becoming
> unavailable.
Sounds right to me. However, I made the change primarily to have better
start-up stability without having to leave the power supply running 24/7.
>From a cold start, the OCXO's frequency makes a relatively large excursion
until it comes up to temperature. That said, I found Ten Tec's TCXO to be
significantly more stable than the OCXO ever was. After the mod, I don't
believe I saw more than a 20 Hz change in frequency at 14 MHz -- even from a
cold start.
If Ten Tec no longer carriers that particular TCXO, many inexpensive
replacements are available with 0.5 ppm accuracy or better. The difference
in price is generally a function of the TCXO's phase noise spec and absolute
stability required.
Paul, W9AC
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