[Elecraft] KTCXO3-1 TCXO

[Chad Wasinger]

Side question: Does anyone know the exact location of the temperature sensor for the FP reading on the K3? 

> From: chadwasinger at outlook.com
> To: kl7uw at acsalaska.net; elecraft at mailman.qth.net
> Date: Mon, 4 Feb 2013 09:24:44 -0600
> Subject: Re: [Elecraft] KTCXO3-1 TCXO
> 
> 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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