Electrical Frequency Synthesizer 1A14 Circuit Functioning

TM 11-5820-695-35

orderwire circuits. Transistor circuit Q2 is used as a

sidetone amplifier and is connected between the

transmit and receive elements of Handset H156/U. The

transmitted signal from Handset H156/U is applied to

the base of Q2 by pin R and capacitor C8. The output

of Q2 (emitter follower configuration) is applied to the

receive element of Handset H-156/U through resistor

R22 and pin S. Resistors R20 and R21 provide the

proper bias for transistor Q2. Dc power is supplied to

the microphone of Handset H-156/U through dropping

b. Indicator Lamps. Two power indicator lamps

resistor R18.

on electrical equipment chassis 1A14A10 indicate the

presence of the +28 volt and +6 volt power from power

2-56. Electrical Frequency Synthesizer 1A14 Circuit

supply 1A14A8.

Operational indicator lamps are

Functioning

provided on plug-in components 1A14A1-1A14A6. A

lighted (red) lamp indicates a failure in the associated

Electrical frequency synthesizer 1A14 provides an rf

plug-in components.

output frequency in the range of 284.275 MHz to

303.125 MHz. The 1A14 output is applied to transmitter

amplifier-frequency multiplier 1A11 in the T1054/GRC-

c. Integrated Circuit Z1. Integrated circuit Z1 (type

144 and to amplifier-frequency multiplier 2A10 in the R-

933) provides a diode distribution network for the +5 volt

1467/GRC-144.

Figure 5-45, electrical frequency

lamp test signal. Pressing TEST pushbutton S2 applies

synthesizer 1A14 interconnecting diagram, shows the

5 volts dc to this network which, in turn distributes it to

chassis mounted components and plug-in component

the individual operational indicator lamp bias circuits.

connections.

The circuit theory for the plug-in

components is given in paragraphs 2-57 through 2-64.

d. Relay Circuit.

Relay K1 is controlled by

All circuit theory and associated illustrations also apply

application of power to the crystal oven in standard rf

to electrical frequency synthesizer 2A14 in Receiver,

oscillator 1A14A7 Relay K1 is shown in the deenergized

Radio R1467/GRC-144.

position which indicates that the crystal oven has

reached its operating temperature.

a. Thumbwheel Switches.

Four thumbwheel

switches: S1-I (S1-II dummy), S1-III, S1-IV, and S1-V

When the crystal oven is not at its operating

(fig. 5-45(1)) provide +6 vdc return (ground) connections

temperature, 28 volts de is applied to the relay coil from

to the switch gate inputs of variable frequency dividers

pins 4 and 6 of plug XA7. This energizes relay K1 and

and 1A14A5 in accordance with their settings; the

provides an open circuit at pins A3, B3, causing the

contact configurations for each thumbwheel .switch

SYNTH OVEN indicator on meter panel assembly

setting are indicated below. An X indicates the switch

1A15A8 to go out.

closed position which applied a +5 vdc return (ground)

line to the associated switch gated input.

2-57. Radio Frequency Oscillator 1A14A1 Circuit

Functioning (fig. 5-46)

a. Power (+28 volts dc) from power supply 1A14A8

is applied through pins 1 and 5 of connector P1 to

terminal E12 on board A3 and to the input of voltage

regulator VR1. This regulator produces 21 volts + 1

percent which is applied to radio frequency oscillator

(vco) Y1 through rf choke L13, to board A4 through rf

choke L4 and to board A2. RF feedthroughs FL1, FL2,

and FL3 filter rf currents which might adversely affect

the circuit operation.

b. The rf output frequency generated by the radio

frequency oscillator Y1 is determined by the vco bias

voltage produced in audio frequency phase error

detector 1A14A3 and applied through coaxial connector

P1-A3

and

terminal

El.

The

2-94 Change 3