Re: HP 10544 OCXO

From: Arnd Gronenberg (arnd_at_gronenberg.com)
Date: 01/11/05 

Date: Tue, 11 Jan 2005 21:30:35 +0100

DaveM wrote:
> Arnd,
> There is some really good info on the HP oscillator at
> http://www.realhamradio.com/GPS_Frequency_Standard.htm, which describes uses
> for the HP Z3801A GPS Receiver/Time Standard. The page at
> http://www.realhamradio.com/z3801a-turning-point.htm gives you some really
> great info on setting the crystal turning point temperature for the best
> stability. This will help you to understand your questions about the
> thermistor also. The oven isn't set to a standard temp, but to the best
> temp that puts the crystal in the middle of its curve. The thermistor is
> spec'ed at 100K @ 25C and 9.93K @ 80C. You'll have to shop around for a
> suitable replacement, keeping in mind the physical size of the thermistor.
> [...]

Hi Dave,

thanks a lot for your reply! And also to Fred for his remarks.

The information regarding the temperature calibration is very helpful. I
found a replacement thermistor, which seems to be suitable: 83K @ 25C,
10.24K @ 80C, reaction time 0.7s, size 1.5mm diameter.

As the HP 10544A uses an AT cut crystal I assume that I have to
calibrate for a frequency minimum (according to the above mentioned
website). As the HP 10544A contains a 10 turn variable resistor instead
of a hand-picked resistor, calibration should be quite straight forward.

Thanks again, best regards, 73,
   Arnd 

-- 
                                Arnd Gronenberg
                          EMail: arnd@gronenberg.com
                              HAM: DJ9PZ / AB2QP