COMPONENT MAINTENANCE MANUAL
IN 1502H RADAR INDICATOR
TM109102
1-38
May/01
Diodes CR5008 and CR5010 isolate the outputs of U5002B and U5002C from one
another, ensuring that the operational amplifier with the lowest output controls VCO
frequency. In typical operation the output of current limiter U5002B is around 11 volts,
while voltage regulator U5002C controls frequency with an output of about 2.5 volts.
Dual diode CR5011 provides a voltage drop to offset the voltage drop of the
conducting isolation diode. It provides a large enough voltage drop to ensure that zero
volts will be applied to the VCO frequency control when U5002B or U5002C demands
minimum frequency, even if the operational amplifier cannot drive its output quite to
zero.
(6) Voltage Output Circuit
Various voltage outputs (+5 volts, +12 volts and +52 volts) are tapped from the
secondary of power transformer T5004, full wave rectified, filtered and supplied to the
circuits of the indicator via J5011. The +9 volt outputs are derived from the +12 volt
outputs. The +9 volt outputs are Zener regulated and use very little current.
The fi28 volts and +12 volts are also routed to the high voltage power supply
via J50-12. An additional DC voltage, +6.3 volts for the CRT filaments, is full wave
rectified and routed to the CRT via J5012 and the high voltage power supply.
The +5 volts is fed back to the voltage regulator circuit to permit regulation, as already
explained. Surge suppression diode CR5014 protects against voltage transients on
the +5 volt line.
The document reference is online, please check the correspondence between the online documentation and the printed version.
