TM 11-5820-801-30
are connected to two poles of a single throw switch (S4
2-18.
Local Control and Monitoring Circuits
or S5). The common terminal of the switch (S4-2 or S5-
2) is connected to the panel test jack J5 or J6) and to the
source of the varactor bias voltage is the + 12 volt
varactor diode in the parametric amplifier stage (2A3,
regulator in Regulated Power Supply 1PS1. A voltage
first stage or 2A2, second stage). The varactor diode,
divider consisting of a 1-kilohm fixed resistor (E1R8 or
then, always has a bias voltage applied: either from the
E1R9) and a 1-kilohm variable resistor (R5 or R6) is
wiper arm of the variable resistor (normal operation) or
connected across the + 12 volt regulator output. The
from the midpoint (+6 V) of the voltage divider (BYPASS
bias voltage is taken off the low side of the divider (12-
operation). E1R8 and E1R9 are mounted on terminal
volt return line) and either the wiper arm of the variable
board 1E1; R5 and R6, S4 and S5 are mounted on the
resistor or the center of the voltage divider. The bias
rear panel of Unit 1 (fig. 3-2).
voltage can therefore be varied from 0 to +6 V. The
wiper arm line and the line to the voltage divider midpoint
Figure 2-15. Varactor Bias Voltage Circuit , P/O Unit 1.
b. Voltage Measurement Circuit (fig. 2-16).
the M4 circuit is open. When S2 is set to BEAM the
voltage drop across
During normal operation selection switch S2 for
VOLTAGE meter M4 is set to OFF, in which condition
2-20
