Figure 2-4. Antenna Coupler Control Unit Schematic Diagram.

TM 11-5820-873-34

Figure 2-4. Antenna Coupler Control Unit Schematic Diagram.

board 2A4.

Board 2A4 develops phase (2A4-2),

2-13. Detailed Theory of Operation

amplitude (2A4-5) and reflected power (2A4-3) error

(Fig. FO-5 and Fig. FO-32)

signals. Each of these error signals is referenced to the

To begin a tune cycle, the RT-1277/URC-92 mode

10 volt line. The reflected power signal goes to control

switch must be set to CPLR TUNE KW. The CPLR

logic board 2A1 pin 15. It is used as a control signal for

TUNE KW position provides the ground necessary to

many AN/URC-92 operations. Phase error between

energize relay 2K1. When 2K1 is energized, +28 VDC

2A2-2 and 2A2-3 is processed and a corrective drive

(CPLR tune +) is present at one side of the antenna

signal is produced. The home drive is removed and the

coupler control TUNE START switch. Depressing TUNE

corrective drive takes over as soon as the phase

start returns the +28 VDC (CPLR tune + R) to the

becomes positive. The corrective drive signal for phase

antenna coupler control logic board 2A1 pin A. The +28

occurs at either 2A2-4 or 2A2-5 depending upon the 2C1

VDC at 2A1-A generates a keying signal at 2A1-7, a

adjustment necessary. Amplitude error between 2A2-16

2C1 home pulse at 2A1-13 and a 2L4 home pulse at

and 2A2-U is processed and a corrective drive signal

2A1-R. A ground is supplied, by 2A1-6, to 1A2-3 which

produced for 2L4 adjustment. Again the home drive

lights the COUPLER STATUS TUNING indicator. Also,

signal is removed and the corrective drives takes over,

a ground is present at 2A1-15 which energizes 2K4.

at either 2A2-17 or 2A2-V, when the phase goes

Normally 2K4-9, 1 with 2K4-10, 2 shunt the RF around

positive. The phase and amplitude corrective drive

the 3 dB attenuator.

In a tune cycle, with 2K4

signals oscillate until 2C1 and 2L4 are tuned to

energized, the 3 dB attenuator is placed in series in the

minimum reflected power. At that point, 2A2 causes a

RF line. The 2A1 home pulses enter the phase and

motor braking action at 2A2-T and 2A212. The servo

amplitude control board 2A2 on pin 6 for 2C1 and pin R

motor control (2A6) receives the drive signals from 2A2

for 2L4. The home pulses set 2A2 flip-flops to provide a

and amplifies them to drive 2M1 and 2M2 as necessary.

homing signal at 2A2-5 for 2C1 and at 2A2-V for 2L4.

Motors 2M1 and 2M2 then adjust 2C1 and 21L4

Simultaneously, the transceiver produces an RF output

that is sensed in the phase and amplitude detector

2-16