Posted by
Don Wilhelm-3 on
Dec 24, 2006; 3:19pm
URL: http://elecraft.85.s1.nabble.com/K2-frequencyh-stability-tp442294p442298.html
Adam,
I assume you are referring to drift of the 4 MHz master oscillator and not
to a drift in the PLL reference oscillator.
Drift in the 4 MHz reference is of little to no consequence in normal
operation of the K2. It is only important at the time CAL PLL and CAL FIL
are performed.
The K2 does not use the 4 MHz reference to count the frequency on a
real-time basis. The values obtained during the CAL PLL and CAL FIL process
are retained in EEPROM and those values are used for control and display of
the K2 frequency, so the 4 MHz oscillator may drift many kHz and all will
still be well with the K2. The 4 MHz oscillator does serve as the clock
signal for the microprocessor, but it's accuracy is not important for that
use.
If you wish to achieve good dial calibration on the K2, warm the K2 up to
operating temperature before calibrating the 4 MHz reference oscillator and
running CAL PLL and CAL FIL. Instructions for calibrating the K2 dial to an
accuracy of 10 to 20 Hz can be found on my website
http://w3fpr.qrpradio.com.
73,
Don W3FPR
> -----Original Message-----
> From:
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> Sent: Sunday, December 24, 2006 8:48 AM
> To:
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> Subject: [Elecraft] K2 frequencyh stability
>
>
> Hello all,
>
> I notice that on K2 #03547 rev B (with KPA100, KDSP2, KSB2,
> K160RX and thermistor installed at time of build) the master
> frequency drifts as a function of temperature. From an
> ambient temp of 65F to max rig temp when the KPA100 fan
> kicks in the receiver may drift by 800 Hz. The range is
> usually more narrow given the typical temp shift experienced.
>
> My solution has been to calibrate C22 against WWV such that
> as the rig warms up, the master frequency set by C22 drifts
> towards zero-beat with WWV.
>
> My question is this: how much drift is typical?
>
> Adam, N1KO
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