Your first number is bogus, but generally speaking if your other numbers are
correct, that does seem excessive. That said, crystals do age and some of this
depends on power on/off cycles. I'm now to the point of leaving my K3S powered
continuously.
I recently ran some drift tests and found that it takes about 25 minutes for my
reference to settle to a point limited by measurement jitter. There is an
initial positive increase of a few Hz at power up (at room temperature) then a
non-linear decrease of about 25 Hz.
(Direct measurement of the synthesizer output with a FA-2 counter by BG7TBL,
with a Bodnar GPSDO reference)
Wes N7WS
On 12/4/2019 1:33 PM, Gary Peterson wrote:
Last February, I purchased a factory assembled K3S including a 1 ppm TCXO. The
transceiver is serial number 11803 and the firmware was updated on May 5th of
this year.
Last July, I noticed that many of the signals on 50.125 MHz sounded as if they
were a bit off frequency as they were higher pitched. This led me to believe
that the reference oscillator may have drifted, possibly due to crystal aging.
Subsequently, I used method 2 and WWV, as described on page 53 of the Elecraft
K3S manual. The REF CAL frequency was lowered from 49.999.996 to 49.379.448.
That seemed to make the signals on the 6 meter calling frequency sound like
they should.
A few days ago, I caught a six meter opening and signals on 50.125 sounded
higher pitched again. I repeated the reference oscillator calibration again,
using method 2. Now, the REF CAL frequency is set to 49.379.110. I have not
had the opportunity to hear any six meter signals, since I changed the
reference oscillator.
I am wondering if the REF CAL frequency change that I have seen in less than a
year is normal, or whether I have a TCXO problem.
Any thoughts would be most appreciated. Thanks in advance for any time taken
to reply.
Gary, K0CX
Rapid City, SD
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