POWER DISTRIBUTION.

TO 31R2-2GRC171-2

TM 11-5820-815-14

NAVELEX 0967-LP-544-5010

relay is deenergized if the squelch is turned off, or if the

incoming rf signal decreases below squelch threshold, or

module A6. In addition, the +26-V de voltage is applied

if the transmitter is keyed (key 1 key line).

to the C-7999/GRC-171 to power panel lights and to the

power lamp (AlOAlDS1) on the front panel to provide

indication that the radio set is turned on.

4-29.

POWER DISTRIBUTION.

4-33. Internal to dc-dc converter module A5, +26 V dc

4-30. Refer to the power distribution diagram of figure

is applied to a second dc-dc converter that develops 100,

FO-14. The power supply for the receiver- transmitter

10, and -17 V dc (-12 and +5 V dc). The 100-V dc output

consists of de-de converter module A5, voltage regulator

is applied through a low-pass filter (L10- C12) to rf filter

module A6, and power supply components mounted on

module A7. The other two voltages from the dc-dc

chassis A10. Unless otherwise specified, reference

converter are applied through low-pass filters (L1-C1, L2-

designators apply to chassis A10.

C2, L7-C8, and L8-C9)tothe+5.1- and -12-volt series

regulators of voltage regulator module A6. Positive 26 V

4-31. Input ac voltage (J7-B and A) or battery voltage

dc from the regulating dc-de converter is applied through

(J7-E and D) is applied to the front panel POWER

a low-pass filter (L4-C4) to the +12-volt series regulator.

ON/OFF switch (A10AlSl) through the emi filter and the

In addition to +5.1, 12, and +22 V dc, the voltage

filter formed from chassis-mounted inductors and

regulator module provides zener regulated +14 V dc and

capacitors. When the POWER switch is on, ac voltage

a diode developed -0.7 V de. The output voltages from

is applied through fuses A10A1F2 and A10A1F3 to

the voltage regulator module are applied to circuits of the

transformer T1. In figure FO-14, transformer T1 is

receiver- transmitter. The -0.7-V dc voltage is applied to

shown connected for 120-volt operation. Through a

the REMOTE/LOCAL switch.

The purpose of this

strapping option on chassis A10 (refer to figure FO-34),

voltage is to compensate for the diode drop of isolation

the input to transformer T1 can also be connected for

diodes used in the frequency select circuit and in the

105-, 210-, or 240-volt operation. The output of T1 is

power on-off circuit.

rectified and filtered into an unregulated dc voltage by

rectifier diodes CR1 and CR2 and filter capacitors C15

and C16. The battery voltage from the power switch is

4-34. The remote on/off input to the regulating de-dc

applied to the filter capacitors through fuse AlOAlF1 and

converter is used to turn the radio set on and off. When

diode CR3. Diodes CR1, CR2, and CR3 provide

the remote on/off input is open, the regulating dc-dc

isolation between the ac and dc power sources. Either

converter is on and power supply voltages are applied to

power source can power the radio set. Floating the

turn the radio set on. When the remote on/off input is

battery across the power supply provides automatic

ground (0 volt applied), the regulating dc-dc converter is

backup power in the event of an ac power failure.

off. This causes all power supply voltages to go to zero

Through a battery charger connected to the battery

to turn the radio set off. When the REMOTE/LOCAL

charger output (J22-c), the battery can be maintained in

switch is in the REMOTE position, the radio set is turned

a fully charged condition while operating off the ac power

on by setting the C-7999,/ GRC-171 PWR ON,/OFF

line.

switch to ON which opens the remote on/off line. When

the PWR ON/OFF switch is set to the OFF position, -0.7

V de is applied through diode CR16 of the C-7999/GRC-

4-32. The unregulated de voltage is applied to the

171. This applies 0 volt to the remote on/off line to turn

regulating dc-dc converter of de-de converter module A5.

the radio set off. To turn the radio set on locally when it

Through a remote sensed output, the dc-dc con- verter

has been turned off remotely, the REMOTE/LOCAL

maintains regulated +26 V de across filter capacitor C14

switch is set to the LOCAL position. This opens the

The regulated +26 V de is applied through filters FL1 and

remote on/off line to turn the radio set on. To turn the

FL2 to power amplifier module A8 and through a low-

radio set off locally when it has been turned on remotely,

pass filter (L5-C6) to the 22-volt series regulator of

the front panel POWER switch is set to OFF. This

voltage regulator

removes input voltage from the regulating dc-de

converter.

4-5/(4-6 blank)