Date: Sun, 3 Feb 2013 08:45:36 -0600
From: Chad Wasinger <[email protected]>
To: "[email protected]" <[email protected]>
Subject: [Elecraft] KTCXO3-1 TCXO
Message-ID: <[email protected]>
Content-Type: text/plain; charset="iso-8859-1"
Does anyone know the approximate warm-up/stabilize time of the KTCXO3-1?
Thanks,ChadN0YK
----------------
Chad,
I observed the action of my TCXO3-1 closely after initial
installation of the EXREF. I noted from cold start up that the TCXO
was receiving a continued updated offset for about 20 to 30 minutes,
whereby it stabilized out at about an offset of about 78-80. From
that time on the offset would only wander a couple points over several minutes.
A check of my 28-MHz transmit frequency accuracy was within 2-Hz
(indicating 0.1 ppm) and would only occasionally change by 1-Hz
reflecting the slow drift of the TCXO between reference checks with
the external 10-MHz source. Running the TCXO-3 without the EXREF
accuracy is aprox. 0.5ppm or on 28-MHz this translates to a maximum
error of +/- 14-Hz.
Freq. measurements are made with an EIP-538 microwave counter that is
referenced to a Rubidium 10-MHz reference. The K3EXREF is referenced
to a separate OCXO which is run on a battery full-time. Short-term
stability of the OCXO is +/-5 E-12, Long-term stability is +/-5 E-5
which requires adjustment about every four months to correct about
1-Hz long-term drift. I have a 200K ten-turn helipot for adjusting
the OCXO frequency. I use my Rubidium as frequency reference which
is +/- 5 E-11 after 30-min warmup. GPS is more accurate but I find
the Rubidium sufficient for my needs. eg: 10-MHz is 1.0 E+7,
multiplied by 5 E-11 = 5.0 E-4 Hz = 0.0005 Hz
See details of the EXREF (and TCXO3-1):
http://www.kl7uw.com/K3EXREF.htm
73, Ed - KL7UW
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