Operation
Operation Instructions
2
2-13
2.4.8.3 Underranging and Overranging Conditions
The 35360A TRACKER Display displays an underrange indicator when a preset threshold has not yet
been reached, and an overrange indicator when the electrometer’s maximum limit has been exceeded
(see Figures 2-22 and 2-23).
An underrange occurs in the percent-of-center measurement mode when the central exposure is too
small to precisely calculate percentages.
Figure 2-22.
Underranging the Electrometer
Figure 2-23.
Overranging the Top and Night Channels of the Electrometer
Table 2-1 summarizes the underrange and overrange conditions and results.
Table 2-1. Underrange and Overrange Conditions
Measurement Mode
Condition
Chamber Reading
Absolute
Overrange a chamber
OVER for chamber
Percent-of-Center
Exposure at center chamber too small to
calculate percentages
UNDER for all peripheral chambers
Percent-of-Center
A peripheral chamber overranges
while center chamber is within range limit
OVER for peripheral chamber
Percent-of-Center
Center chamber overranges OVER
for
all
chambers
2.4.9 Battery and Bias Annunciators
As already discussed, the 35360A TRACKER Display continuously monitors the ion chamber bias and
battery voltages. If either one of these values is outside the specified range, the 35360A TRACKER
displays an annunciator to indicate the error. Table 2-2 specifies these annunciators.
Table 2-2. Bias and Battery Annunciators
Condition Annunciator
Low Bias voltage
LoBias
High Bias voltage
HiBias
Low Battery voltage
LoBat
