Control Logic Board 2A1 Detailed Functional Operation

TM 11-5820-873-34

respectively to the correct position for minimum

of the Reflected Power Amp develops logic 0 at U6A-1

reflected power When reflected power has been

Gate 2A1U6A then establishes logic 1 at 2A1U6B-4 and

adjusted below the threshold, control logic board 2A1

2XA1-14, which is the 50 (+) output. Gate 2A1U6B

ends the tune cycle The COUPLER STATUS READY

generates logic 0 at 2AIU6C-9 to reset the FF If RF is

Indicator is illuminated by a ground at 2A1-N and the

not present during a tuning cycle, the FF also resets but

AN/URC-92 is ready for transmitting

is set again by 2A1Q19 and 2A1U5C. The 50 Ohm FF

2-14. Control Logic Board 2A1 Detailed

is also set, and triggers 2A1Q14 if any of the following

Functional Operation

conditions occur the Time Delay running out or variable

inductor 2L4 reaching L max will set the FF thru

(Fig FO-6 and Fig FO-33)

2A1CR15 and/or 2A1CR16 respectively. Also, some

frequency-impedance combinations may cause the FF

Board 2A1 provides control co-ordination for the

to reset and the tuner will not tune. This situation occurs

automatic tuning cycle The logic outputs of 2A1 provide

if reflected power rises above threshold during the same

initiation, cycling, completion and fault signals The

tune cycle Then an RC network, 2A1R29 and 2A1C36,

control logic board Is divided into eight functional blocks

charges to trigger 2AlQ13 Then 2A1Q13 established a

which will he discussed Individually The eight functions

logic 0 at 2A1U6D-13 to set the FF, 2A1U6D1 1, at logic

are Tune flip-flop, 50 ohm flip-flop, Fault flip-flop, Time

1 and trigger 2A1Q14 on. With that the 3 dB attenuator

Delay, C3-C6 control, Reflected Power Amp, RF

Is again switched in to prevent transmitting into a

Detector, and Lamp Driver

possible open or short circuit.

a. Tune Flip-Flop The Tune flip-flop is comprised of

2A1Q10, 2AlQ15, 2A1U3B-C-D, 2A1U4C-D and all

c. Fault Flip-Flop. The Fault FF consists of 2A1U4A-B,

related components When the unit is first turned on,

2A1U5A-B-D,

2AICR12,

2A1CR13

and

their

2A1U3B-6 is at a logic 0 due to circuit loading.

corresponding circuits When power is first applied

Depressing the TUNE START pushbutton on the

(transceiver turned on), circuit loading causes 2A1U4B-6

antenna coupler control (1A2) applied + 28 VDC to

to be logic 0 and set the FF The logic 1 at 2alU4A-3 Is

2XA1-A The +28 VDC turns on 2A1Q15, causing a logic

then fed to the Lamp Driver to light the COUPLER

0 at the collector, which initiates a tune cycle The logic 0

STATUS FAULT indicator. When the mode switch is

initiate signal resets 2AIU3C-8 causing a logic 1 at

set to CPLR TUNE KW, +10V is switched to 2XA1-2

2A1U3B-6 Because of this, 2AlQ10 turned on and

thru 2K1. The + 10V is applied to an RC network and

ground the Interlock (2XA1-7) which keys the transmitter

voltage regulator, in the Fault FF to generate a single

on in am The 2AlU: 3B-6 output is also fed to the Lamp

logic 1 pulse This pulse is inverted by 2A1U5D and the

Driver to light the COUPLER STATUS TUNING

logic 0 makes 2A1U4B-6 a logic 0 The logic 0 is also fed

Indicator The same logic 0 initiate signal is used in all

to Tune FF 2A1U3D-13 to extinguish the CPLR TUNE

the other functions except the [,amp l)river It also

READY indicator The output of 2A1U4A-3 is then at

provides the 2C1 home (2XA1-13) and 2I,L4 home

logic 1 and fed to the Lamp Driver to light the

(2XA1-R) outputs The Tune FF is reset, when the tune

COUPLER STATUS FAULT indicator The Fault FF is

cycle ends, by a logic 1 at 2AlU4C-9 from the Reflected

also set by a logic 0 from 2A1U5A-11. A logic 0 from

Power Amp which produces logic 0 at 2AlU4C-8 That

2A1U5A is caused when two conditions are met First,

logic 0 resets the Fault FF and the Tune FF which

the reflected power is above threshold and Reflected

extinguishes the COUPILER STATUS TUNNG Indicator

Power Amp 2A1Q3 causes a logic 1 at 2A1U5A-13.

At the same time 2A1U41)-11 is at a logic 1 which is fed

Second, Tune FF 2A1U3C-8 produces a logic 1 at

to the Lamp Driver to light the COUPLER STATUS

2A1U5A-12, indicating tuning is not in process This

REAI)Y indicator

ensures. the COUPLER STATUS FAULT indicator will

light any time timing is required due to antenna or

frequency change If the Time Delay runs out, the Fault

b. 50 Ohm Flip-Flop The 50 Ohm FF includes

FF will he set with a logic 0 from 2A1CR20 to 2A1U4B-

2AlQ13, 2A1Q19 1A1U6A-B C-D, 2A1U4C and

associated components When a tune cycle is Initiated, a

Reflected Power

Amp

Components

logic 0 is placed at 2AlU6C-8 and sets the FF with a

2A101.2A1Q1, 2A1Q2, 2A1Q3.

2A1Q4, 2A1Q5,

logic 1 at 2AlU6D-11 The logic 1 triggers 2A1Q14 to

2A1CR1, 2A1CR2 and associated resistors and

provide a ground, for energizing 2K4, at 2XA1-15

capacitors make up the Reflected Power Amp From

Energizing 2K4 switches the 3 dB attenuator in series

2X1A-3 a DC voltage, proportionate to reflected power

with the rf transmission line When reflected power drops

on the transmission line, is fed to 2A1U1-4. This signal

below threshold or RF power is not sensed by the RF

Is referenced to + 10 VDC and 2AlU1 develops its

Detector, the 50 Ohm FF is reset This causes 2A1Q14

output from that reference. The output at 2A1U1-10,

to cease conduction and 2K4 deenergizes, taking the 3

along with a gain input (2XA1-8) from the antenna

dB attenuator out of the transmission line If the reflected

power is below threshold, 2A1Q3

2-17