RADAR TEST SET
THEORY OF OPERATION - Continued
state. The active-state configuration settings are stored when the unit transitions to standby mode. To
restore the Test Set to the active state press any button (S1, S2, or S3). The display and all settings return to
their pre standby-mode state and the unit is fully operational.
Starting a test initiates a self-calibration cycle if the Test Set detects either of the following two conditions:
Thirty (30) minutes or more has passed since the last self-calibration.
A change in temperature of five (5) degrees C or more is detected since the previous self-calibration.
Self-calibration performs the following calibration functions:
Tracking Filters (transmit and receive)
DETAILED THEORY OF OPERATION
External Power Regulator
External 12 to 28 V (nominal) power is EMI filtered and regulated down to +10V by the switching regulator to
power the Test Set. Diodes are used to select either the 10 Volts or the battery voltage. Since the 10 volts is
always greater than the battery voltage, the Test Set load is automatically removed from the batteries when
external power is present.
Ten (10) volts from the regulator powers a constant current source for charging the battery. The current
source is controlled by an integrated circuit that checks for the presence of a battery, limits the charging
temperature range, and terminates charging when the battery is fully charged. The IC determines that a
battery is fully charged by detecting the small voltage drop that occurs when NiCad or NiMH batteries are fully
charged under constant current. For safety purposes, backup charge termination is also provided by a
temperature sensor which shuts down the charger to prevent battery overheating.
COMSEC Power Supply
The Test Set supplies power to the external KIR-1C computer for code loading. This eliminates the need for
a 28 V dc or 115 V ac source during code loading. The power supply is enabled by the Test Set during code
loading, and supplies 28 V dc at up to 5 watts. In addition, the supply provides power to the KIT-1C COMSEC
when attached during interrogator testing. The Test Set COMSEC power supply is not compatible with KIT-1A
or KIR-1A computers because of their higher power requirements.
Over Current and Over Temperature Protection
The TS-4530/UPM Test Set provides over current protection for power supplied from the internal battery and
from external power. This protection is provided by a device for each power source that will automatically
switch to a high impedance state when exposed to excessive current. These devices will automatically reset
when power is removed. Disconnect the Test Set from external power and remove the battery for a period of
1 minute at room temperature to insure resetting of the protective device. If the Test Set is at an elevated
temperature, the protective device will take longer to reset. Allow the unit to cool to room temperature to
insure proper resetting of the protective device.
The Test Set also incorporates a safety thermostat in the battery compartment to reduce the possibility of
battery venting due to excessive temperatures.
If the battery compartment temperature exceeds
approximately 80 degrees C, the battery will be disconnected. The thermostat will automatically reset when it
cools to approximately 40 degrees C. Disconnect external power and remove the battery, then allow the unit
to cool for one hour at room temperature to reset the thermostat. The thermostat responds to any excessive