1-Mc Spectrum Generator Module A15

ing of diode CR3, capacitor C5, and re-

transformer T2 to 7 mc. Capacitor C4 is

an emitter bypass. Resistor R5 is the

sistor R8, to the center tap of the primary

emitter swamping resistor for Q2. The

of transformer T2. It is terminated in a

10-volt dc supply is decoupled from the 1-

tuned network consisting of capacitor C4,

mc spectrum generator by coil L1 and

inductor L1, and resistor R7. The network

capacitor C6.

is broadly tuned to 7 mc. The spectrum

generator output contains the 1st through

the 12th harmonic of the fundamental 1-mc

24. Interval Oscillator Module A10

pulse. Since the signal level of each suc-

(fig. 19)

ceeding harmonic is reduced in amplitude

from the signal level of the preceding

Interval oscillator module A10 supplies

harmonic, the terminating tuned network

the fss with two crystal-controlled signals.

is used to equalize the harmonic compo-

This module has two crystal-controlled

nents of the generated spectrum.

oscillators; Q1, generates frequencies of

c. The mixed signal in the secondary of

46.85 mc to 47.75 mc in 100-kc incre-

ments, and Q2 generates frequencies of

transformer T2 is approximately 53 mc.

The output of the fss first mixer is applied

5.55, 5.60, and 5.65 mc.

to 53-mc filter A13. The rf signal input

a. 46.85-47.75-Mc Oscillator Q1.

from Q1 to the fss mixer can be measured

(1) Transistor Q1 is connected in a

at test jack J2. The rf input from module

crystal-controlled oscillator that

A15 to the fss mixer can be measured at

uses 1 of 10 crystals. Crystal se-

test jack J3.

lection is determined by the kc

tuning control on the front panel.

The toned collector circuit is com-

23. 1-Mc Spectrum Generator Module A15

posed of capacitors C1 and C2 and

(fig. 18)

the primary of transformer T1.

Oscillation is sustained by feeding

The 1-mc spectrum generator module,

back part of the energy in the col-

A15, produces harmonics of the l.0-mc

lector tank through capacitor C3

crystal-controlled oscillator for injection

and resistor R2. Resistor R4 is

into fss mixer module A14 (para 22).

the tuned circuit damping resistor.

Module A15 consists of a 1-mc cyrstal

(2) Resistors R1 and R2 form a volt-

oscillator and a pulse generator.

age divider network which develops

a. The 1-mc crystal oscillator is a mod-

ified Hartley type. Transistor Q1, fixed

the base bias for Q1. Resistor R3

is the emitter swamping resistor.

capacitor C2, coil T1, and crystal Y1 form

Resistor R18, inductor L1, and

the oscillator circuit. Resistors R1 and R2

capacitor C 16 form a filter net-

form a voltage divider which provides the

fixed bias portion of emitter-base bias.

work in the +10-volt supply to Q1.

The rf output of Q1 can be meas-

Resistor R3 is the emitter swamping re-

ured at test jack J2.

sistor for Q1. Capacitor C1 bypasses the

base to ground.

b. Oscillator 5.55, 5.60, or 5.65 Mc Q2.

(1) Transistor Q2 is connected in a

b. The sinusoidal 1-mc oscillations are

applied to pulse generator Q2 through

crystal-controlled oscillator cir-

cuit that uses one of four crystals

coupling capacitor C3. The pulse generator

is normally cut off by the reverse base

(three frequencies) to generate the

frequency reference for p has e

bias applied through, R4, and conducts

comparison in module A17. The

only on the negative half cycles of the 1-

mc signal. a positive pulse, rich in har-

tuned collector circuit is made up

monics, is developed in the collector out-

of capacitors C9 and C10 and the

primary of transformer T2. Oscil-

put. This output is applied across the

lation is sustained by feeding back

transformer T2 and coupled to first mixer

module A14.

part of the energy in the collector

circuit from the junction of C9 and

c. Capacitor C5 broadly tunes output