To add a little to what Wes said:
The K3 TCXO rest freq is 49,380 KHz. It is a temperature corrected
oscillator so will still drift with radio warm up but less than a
non-compensated oscillator. So best to calibrate after at least
30-minutes warmup. If you have the 100w model K3, there will be some
temperature drift when transmitting (varies with mode and frequency band).
I have the EXREF installed with the TCXO-03 and that holds my 50-MHz
signal within 3 Hz. But if you check the TCXO frequency (CONFIG: REF
CAL) you will see the frequency drift. Mine seems to top out at
about 49.380.090 and then hold within a few .001.
The EXREF takes the need for periodic re-calibration away. But your
10-MHz reference needs to be very accurate/stable. I use a surplus
OCXO that needs re-calib about every 4-6 months (usually only 1-Hz
drift). My OCXO runs 24/7 to avoid warm up drift.
Hope that helps.
73, Ed - KL7UW
From: "Gary Peterson" <[email protected]>
To: <[email protected]>
Subject: [Elecraft] TCXO drift and calibration
Message-ID: <C8C8661341DC47FCB5BF558A94B08417@WIN7LowProfile>
Content-Type: text/plain; charset="iso-8859-1"
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
73, Ed - KL7UW
http://www.kl7uw.com
Dubus-NA Business mail:
[email protected]
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