TM 11-6625-2950-13
PRINCIPLES OF OPERATION
(1) The air cooler blower turns onto provide the
needed cooling air to the uhf receiver-transmitter.
Principles of operation will be divided to cover each of
(2) Relay K1 energizes providing a ground return
the individual components of the test set group. These
p a t h from the uhf receiver-transmitter, through the
components are: interconnecting box, air cooler, headset
closed RT ON switch S1 and through the closed contacts
adapter, and indicator. Schematic diagrams of intercon-
necting box, air cooler, and cable assemblies are provided
c. Lamps L1 (DC PWR) and L2 (AC PWR) indicate
to supplement maintenance procedures.
that external power is applied and that circuit breakers
CB1 DC and CB2 AC are closed. Lamp L3 (RT ON)
indicates that RT ON switch S1 is closed and the uhf
a. The interconnecting box provides interface test
receiver-transmitter is activated by the uhf receiver-
points to fault-isolate the uhf receiver-transmitter and
transmitter power supply. Lamp L4 (SWITCHED +27.5
uhf radio control. Figure 2-5 illustrates the interconnect-
VDC) indicates that the uhf receiver-transmitter is operat-
ing box in a functional test setup with the components of
ing and providing a +27.5 vdc output. Lamp L8 (C-10547
the uhf radio set. Headset Adapter MX-9530/ARC is not
ON) indicates that a ground has been supplied to the
u s e d in this configuration. Air cooler connector J1
POWER ON/ OFF circuit of the uhf radio control. This
connects directly to uhf receiver-transmitter connector
lamp lights whenever external power is applied to the
J4. When used in this test setup, the air cooler provides
interconnecting box, CB1 DC, CB2 AC, and RT ON
the required cool airflow to the uhf receiver-transmitter.
switches S1 are on; and when all uhf radio set circuits are
An interlock circuit in the interconnecting box prevents
functioning properly. Lamps L5 (ADF ENABLE) and
t h e uhf receiver-transmitter from operating without
L7 (KY/GD INTLK) indicate that a ground has been
airflow from the air cooler.
applied to the uhf radio set ADF enable and KY/GD
interlock circuits. Lamp L6 (MAIN SQUELCH) indi-
b. The 27.5 vdc power is applied to interconnecting
b o x connector J5. When circuit breaker CB1 DC is
cates that the strength of a received signal is sufficient to
closed, power is applied through connector J1 and to air
open the main squelch gate in the uhf receiver-transmitter.
cooler connector J2. Dc power is then applied from air
L a m p L9 (XMT) indicates that a ground has been
c o o l e r connector J1 to uhf receiver-transmitter J4 to
p r o v i d e d to the transmit keyline. This lamp lights
energize the circuits in the uhf receiver-transmitter. The
whenever the uhf receiver-t ransmitter is keyed.
i n t e r n a l uhf receiver-transmitter power supply is not
d. T e s t p o i n t s T P 1 t h r o u g h T P 5 , w h e n u s e d i n
conjunction with TP6 (ground) provide direct voltage
energized at this time until a ground path is completed in
readings from the uhf receiver-transmitter and indicator,
t h e POWER ON/OFF circuit. This ground return is
I n p u t jacks J6 through J11 provide connections for
accomplished when ac power is applied to the intercon-
necting box. The 115-volt, 60-Hz ac power is applied to
applying external signals into the uhf receiver-transmit-
ter, Output jacks J12 through J16 provide connections
interconnecting box J5. When circuit breaker CB2 AC is
f o r sampling output signals from the uhf receiver-
closed, and RT ON switch S1 is on, two circuits are
transmitter and uhf radio control.
energized as follows: