Elecraft recently posted a modification to the K3REF to correct a problem
caused by the K3EXREF. Though specific to frequency changes noticeable on
on 2M and 6M, I suspect it may directly relate to this discussion.
http://www.elecraft.com/K3/mods/K3EXREF%20freq%20shift%20fix.pdf
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Chuck, AE4CW
Almost.
The TCXO has no control input and is not tuned; it is only measured.
The measurement information is passed to the radio's MCU which then uses
the data to determine the correct value to command the synthesizer(s),
drive the REF CAL display, and so forth.
73,
Lyle KK7P
The K3EXREF
Thanks guys for the detailed and thorough replies - I understand it now!!
Andy G4HUE
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Post:
The K3EXREF circuit is essentially a AFC (sort of) where a highly
accurate 10-MHz reference is used to measure the frequency of the
TCXO and send a frequency correction "word" to control the TCXO so
that the error from 49.380 MHz is removed.
As I understand it this comparison is done about
I believe that is the way it is.
53/1000 of a hertz over an hour?
I'd give that up all day everyday for the spectacular lack of phase
noise in the K3s or K3 with the new synth.
It's not a cesium clock.
On 3/7/2016 8:02 AM, David Anderson wrote:
I -think- the way it works is that when the
I -think- the way it works is that when the K3EXREF is locked with the external
frequency standard on 10 MHz, this is used to measure the frequency of the
TCXO. The value of that frequency measurement is then put into the K3 REFCAL
setting. If the TCXO drifts slightly as they all will, then the
Andy - Without the K3EXREF connected, the REF CAL frequency will be
fixed and the K3 will drift, albeit very slightly, particularly when it
is first switched on. With K3EXREF locked with your 10MHz standard the
REF CAL frequency will vary to correct any drift in the K3. If you
measure the output
Hi Andy,
I have the same (hardware) constellation and get similar results.
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Sometime ago I installed the K3EXREF which I feed from an external 10MHz double
oven Xtal oscillator. I am confident the K3EXREF is installed and configured
correctly as when in use and the external oscillator is connected the front
panel says REF*CAL with the * blinking. Attempting to change
Sometime ago I installed the K3EXREF which I feed from an external 10MHz double
oven Xtal oscillator. I am confident the K3EXREF is installed and configured
correctly as when in use and the external oscillator is connected the front
panel says REF*CAL with the * blinking. Attempting to change
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