[Elecraft] KTCXO3-1 TCXO

[Chad Wasinger]

Thanks you all for responding to this. I also note that it takes around an hour for the larger corrections to settle down and several hours for complete stability to set in.
I've been monitoring my front panel temperature sensor which normally runs 36 C with the radio on for several hours and a shack temperature of 75 F degrees. From a cold start up at 24 C, it normally takes about an hour to reach a constant temperature of 36 C on the FP. I know the FP temp reading and TCXO are separate pieces but at the point of 36 C, I have really notice the TCXO to settle out. 
> Date: Sun, 3 Feb 2013 09:22:57 -0900
> To: Elecraft at mailman.qth.net
> From: kl7uw at acsalaska.net
> Subject: [Elecraft]  KTCXO3-1 TCXO
> 
> 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>
> 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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