Guys,
Put this in the K3. Some questions. Would appreciate some enlightenment
from the experts out there.
It has only three pins which I suppose are +V, ground and signal out.
What does changing REF CAL do since there is no "adjustment" pin?
Also I expected to only have to tweak a well calibrated K3's REF CAL a
small bit after installing the TCXO. Not! REF CAL had to change by 536
to zero beat WWV on 10 MHz. Not found any goofy settings that would
explain that.
Have no way of knowing the internal unit XTAL temp. So I looked at the
front panel temp vs frequency change for the first hour of warm up.
There seems to be little temperature compensation between 19 and 30C
while there is measurable drift. Alternatively the compensation
routines do as good as they can (and much better than the uncompensated
stock oscillator) over this range. Compensation appears good after 30C
up to the 35-36C temps reached after 8 hours. This may be a meaningless
observation. Perhaps the internal KTCX03 electronics temps have
stabilized by then.
Another perhaps meaningless observation. Again using the front panel
temp as an indicator. The unit exhibits a positive temperature
coefficient for the first hour and then becomes negative. The stock
oscillator has a negative coefficient.
It appears to work as advertised. For normal use temperature
transients, it easily makes the +/- 0.5 ppm spec -- overkill for most
everybody. I have some 8 hour long plots of this and the standard
oscillator warmup drift if anybody is interested in the nits.
A literature search on TXCO compensation methods uncovers something
interesting. A neural network approach gets the drift down to 0.005
ppm. It learns how to compensate as it goes.
I wish REF CAL had one more significant digit. The last REF CAL digit
amounts to 0.5 Hz per REF CAL unit at 10 MHz.
The K3 is more than a rig, in many areas it approaches a lab instrument.
I use it as such often.
What are your experiences?
73 de Brian/K3KO
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