HP 83481A, User Manual, Page: 57 / 98

Calibration Overview
Factory Calibrations
The calibration factors are stored in the nonvolatile RAM of the instrument.
There is a switch on the back panel of the instrument that allows the
mainframe calibration to be protected or unprotected. Next to the switch
there is a drawing that shows each switch's function and protected position.
Refer to the optional HP 83480A, 54750A Service Guide for more details
about the mainframe calibration, and the position of the rear-panel memory
protect switches .
C A U T I O N
T o prevent access to the mainframe calibration switch, place a sticker over
the access hole to this switch.
C A U T I O N
Do not attempt a Mainframe calibration without consulting the HP 83480A,
54750A Service Guide.
A mainframe calibration should be performed on a periodic basis , annually ,
or when the ambient operating temperature has changed by and remains
5 C dierent than the operating temperature at which the last mainframe
calibration was performed. T o see how much the operating temperature
has changed since the last mainframe calibration and the date of the last
mainframe calibration, check the Calibration status by pressing the following
key sequence: 4
Utilit y
5 ,
NNNNNNNNNNNNNNNNNNNNNNNNNNNNN
Calibrate , and then
NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN
Cal status on .
The temperature change is displayed at the top of the display as shown in the
following gure .
Figure 3-1. Current Frame 1T emp condition
3-5