220 MHz Frequency Multiplier-OSC 2A13 Circuit Functioning

TM 11-5820-695-35

amplifies the doubled frequency (220 MHz) to a level of

R31, provides a regulated plus 10 volts while zener

70 milliwatts (across 60 ohms). The 110 MHz oscillator

diode CR6 (fig. 2-14(3)) in conjunction with resistor R33

signal is applied through cable A1W1 to the base of

provides a regulated minus 8.2 volts.

input amplifier stage Q1 through attenuator pad R1, R2

and RS and base biasing network C8, R4 and R5. The

amplified 110 MHz signal is capacitance coupled by C4

2-76.

220 MHz Frequency Multiplier-OSC 2A13

to the primary winding (pins 1 and 2) of transformer T1.

Circuit Functioning (fig. 5-58 and 2-27)

Frequency doubler stage Q2 and Q3 is connected to the

secondary windings and conduct on alternate half cycles

The 220 MHz frequency multiplier-osc (fig. 5-58)

of the incoming 110 MHz signal thus, the common

generates a 220 MHz (70 milliwatts, nominal) output

collector signal will be twice the frequency as the input

signal which is applied to receiver frequency mixer

signal.

Inductor LB, in parallel with the output

stage 2A8. The 220 MHz frequency multiplier-osc

capacitance of the frequency doubler stage, resonates

consists of 110 MHz rf oscillator 2A13Y1 and amplifier-

at 220 MHz and variable capacitor C9 tunes LS to 220

frequency multiplier 2A13A1.

MHz and also controls the drive to the base of output

amplifier stage Q4. Zener diode CR1 in conjunction

a. 110 MHz RF Oscillator 2A13Y1 (fig. 2-27).

with resistor R11 provides a regulated 16 volts for

The 110 MHz rf oscillator is a crystal oscillator which

application to the collectors of Q2 and QS of the

produces a 110 MHz (Z 1600 Hz) output signal at a

frequency doubler stage and to the base biasing

nominal power level of 16 milliwatts (across 50 ohms).

network, CR2, R12, R18, and R14 of output amplifier

The 110 MHz output is applied to amplifier-frequency

stage Q4. This stage amplifies the incoming 220 MHz

multiplier 2A13A1 through connector 2A13Y1J1 and

signal and the output is taken from the tuned resonant

coaxial cable A1W1. The oscillator consists of transistor

circuit consisting of autotransformer L4 and capacitor

Q1, 110 MHz crystal Y1, coupling capacitors C5 and C6,

C14. The output signal is coupled to the receiver

bias resistors R4, R5, and R6, and a tank circuit

frequency mixer stage 2A8 through a pad consisting of

comprised of transformer T1 and capacitors C8 and C9.

R16, R17, R18, R19 and R21. The output is adjusted by

Variable capacitor C8 provides a means of tuning the

variable capacitor C14 to provide 70 milliwatts drive

crystal oscillator to the correct stable output power level.

across a 50 ohm load at connector P2. A sample of the

When the +28 vdc supply voltage is applied, the initial

output is detected by diode CRS and is applied to the

surge will cause oscillations to start. The crystal signal

meter selector switch on 2A15A2 through resistor R21

is amplified by Q1 and fed back to the crystal to sustain

and rf filter FL1. Test points designated TP1 + 28V and

oscillations. The 110 MHz output is taken at terminal 3

TP2 CR1 are used for monitoring the +28 vdc and

of T1 and coupled through capacitors C6 and C10 to

regulated 15 volts.

amplifier stage C2. Resistors R7, R8, and R9 provide

attenuation and impedance matching between the 110

MHz oscillator stage and amplifier stage Q2. CR1 and

2-77. Electrical Frequency Synthesizer 2A14 Circuit

CR2 are temperature compensating diodes in the base

Functioning

circuits of Q1 and Q2 The amplified 110 MHz signal

Electrical frequency synthesizer 2A14 is identical to

appears at the collector of Q2 and is coupled to output

electrical frequency synthesizer 1A14 used in

connector J1.

Transmitter, Radio T-1054/GRC-144 (para 2-56 through

2-64).

b. Amplifier-Frequency Multiplier 2A13A1 (fig. 5-

58). Amplifier-frequency multiplier 2A13A1 doubles the

frequency of the incoming 110 MHz oscillator signal and

2-118