Posted by
wayne burdick on
Jul 16, 2012; 11:53pm
URL: http://elecraft.85.s1.nabble.com/KX3-frequency-stability-tp7559264p7559271.html
Tony,
The KX3's temperature stability is specified at +/- 1 ppm typical over
0-50 C. That's +/- 14 Hz on 20 meters. Normally the short-term
stability would be far greater than this. However, during long key-
down periods there is some heating of the RF board, which includes
both the PA and oscillator circuitry.
We included closed-loop temperature compensation for this effect in
hardware and firmware. Normally this compensation is entirely
sufficient, but apparently it doesn't meet WSPR/JT65 requirements.
I should be able to provide a user-settable fine compensation value in
the menu, although it would be a bit of trial and error for the user
to determine the optimal value.
Wayne
N6KR
Tony Estep wrote:
> ....KX3 frequency stability on receive seems fine, as evidenced by
> nice level
> lines on the graph...
> The frequency stability requirements both of WSPR and JT65 are
> considerable. WSPR transmits 4-frequency FSK, with the tones
> separated by
> only 1.5 hz. The whole bandwidth is 6 hz.
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