Posted by
Edward R Cole on
May 20, 2011; 6:03pm
URL: http://elecraft.85.s1.nabble.com/Installed-K3EXREF-tp6188288p6387117.html
Dan,
The K3EXREF controls the TCXO-3 to maintain a near zero offset
compared with an external frequency reference. The K3 synthesizers
are still referenced to the TCXO-3 all the time. So during the
interval between frequency corrections, roughly every four seconds,
the radio frequency is controlled by the TCXO-3. So frequency drift
rate is not affected by the K3EXREF during this interval and only
periodically corrected.
But this does keep the TCXO within 0.05 ppm vs 0.5 ppm.
I was a beta tester and you can see my test results here:
http://www.kl7uw.com/K3EXREF.htmThe largest error observed was +2.5 Hz on 6m.
------------------------------
Message: 29
Date: Fri, 20 May 2011 08:58:55 -0700 (PDT)
From: Dan AE9K <
[hidden email]>
Subject: Re: [Elecraft] Installed K3EXREF
To:
[hidden email]
Message-ID: <
[hidden email]>
Content-Type: text/plain; charset=us-ascii
This may be a naive question but...
If the K3EXREF keeps the K3's reference oscillator within 2 Hz, then what
value is there in using the K3EXREF in conjunction with the KTCXO3 instead
of just the native K3 oscillator?
K3EXREF: 2 Hz error @ 14 MHz : 0.1 ppm
K3TCXO3: 7 Hz error @ 14 MHz : 0.5 ppm
Is the stability in ppm an instantaneous measurement of random error and not
a measurement potential drift over some time delta?
If this is true then using the K3EXREF alone presumably would exhibit the 5
ppm error of the native oscillator in the 4 to 8 second gaps between K3EXREF
syncs. This would make the case for replacing the native oscillator with the
K3TCXO3.
If the stability is measured over time, however, then the K3EXREF and native
oscillator would appear to be sufficient since oscillator drift is
insignificant in the 4 to 8 second time span.
Just curious.
Dan
AE9K
73, Ed - KL7UW, WD2XSH/45
======================================
BP40IQ 500 KHz - 10-GHz www.kl7uw.com
EME: 50-1.1kw?, 144-1.4kw, 432-100w, 1296-testing*, 3400-?
DUBUS Magazine USA Rep
[hidden email]
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