[Elecraft] KTCXO3-1 TCXO

[Edward R Cole]

Date: Sun, 3 Feb 2013 08:45:36 -0600
From: Chad Wasinger <chadwasinger at outlook.com>
To: "elecraft at mailman.qth.net" <elecraft at mailman.qth.net>
Subject: [Elecraft] KTCXO3-1 TCXO
Message-ID: <BAY002-W97BD9BBEC8DB9494E84BF3C0020 at phx.gbl>
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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