As Jerry pointed out correctly, a while back, a TCXO is a Temperature
COMPENSATED Crystal Oscillator, not an oven. Have no idea whether the TCXO
remains powered when the radio is off, but it's going to drift a bit as the
radio/TXCO thermal mass reaches equilibrium.
I have tracked TCXO settling from a cold start in my Orion (with a z3801a), and
what you see seems about right. Using dial setting as a refence, mine starts
out cold ON frequency, then the dial setting drifts about 18 hz high during the
first 30 minutes, then over the next 3-4 hours settles back to within a hz or
two.
I haven't missed a sked or a net as a result :-)
Grant/NQ5T
> Recall last evening after two attempts to adjust my
> Orion TCXO oscillator, I wrote:
>
> > Anyway, both Digipan and MixW are now reading......ta dah:
> >
> > 999.3 up to 1000.1 and down to 998.9. The Orion bottom cover
> > is ON, and it is sitting back in the operating position.
>
> Shortly there after, I powered down the Orion, and the
> 961 power supply.
>
> This morning at about 7:30 AM, I turned both back ON.
> I found the frequency, per the WWVH comparison to be
> about 30 Hz low. After some 30 minutes, was up to
> only 15 Hz low. After about 3 hours, the oscillator match to
> the WWVH signal was within 1 Hz of where it was last evening
> when the rig had been powered up for around 7 hours. And now,
> after another hour, the reading is within 0.5 Hz or so.
> Reading at present using MixW is 999.3Hz, or less than
> 1 Hz from WWVH at 10 MHz.
>
> Does anyone know if the TCXO is still "powered", even if
> the Orion main power switch is OFF, if the main power
> is still on to the Orion input power socket? This was the
> case with my Omni VI+, the TCXO was always ON. If
> so, and if you cared about the sort of warm up drift I
> am seeing, then leave the power supply ON, but shut
> down the main Orion switch as the TCXO would then
> remain "warm".
>
> 73, Jim KH7M
>
>
>
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