Rf Chart (cont)

o f rf amplifier V1, a p p l y the test signal

the frequency output of the tuning unit

t o main unit front-panel SIGNAL INPUT

1 signal generator, as indicated in the

jack J705. Set up the tuning unit 1 signal

chart below. After connecting the test

generator and the test set as shown

signal to the signal injection grid of

mixer V2 and to the plate and grid

in figure 78.

Signal

Possible trouble

Connection

frequency

V2 mixer, signal injection

Defective mixer V2 or oscillator V3; defective oscil-

255 kc (center of band 1

grid, pin 7 (fig. 47).

frequency range)

lator tuned network consisting of C1, C2, C3, R1, and

T1 on band 1 tuner segment 21 (fig. 58); open C54,

R12, R14, R15, R16, or R18; or shorted C52A, C62,

C63, C64, or C65.

V1 rf amplifier plate, pin

Defective tuned network consisting of C4, C5, C6, R2,

255 kc

1 (fig. 47).

and T2 on band 1 tuner segment Z1; open R8 or R11;

or shorted C52B, C56, C57, or C61.

V1 rf amplifier grid, pin 7

Open R10 or wavetrap coil L1, preventing current re-

255 kc

(fig. 47).

turn to V1 cathode; or shorted C52C, C58, or C59.

Poor or no connection at main unit right-angle adapt-

Front-panel SIGNAL IN-

255 kc

PUT jack J705 (fig. 78).

ers CP701 or CP705; defective main unit coaxial

cable W701; defective signal attenuator AT702; open

connection at coaxial Plug P712 which mates right-

angle adapter CP705; open solder connection at ter-

minal A2 on main unit connector J701 or on tuning

unit connector P1; defective input tuned network con-

sisting of C8, C9, and T4 on band 1 tuner segment

Z1; or defective connections between tuner segment

protruding contacts and wiper contact bar (fig. 56).

Note: In following tests, rotate MEGACYCLES switch S1 to remaining five bands, one at a time, and set TUNING dial to same frequency

as for signal generator. If tests at 255 kc (listed ahove) checked out satisfactorily, trouble is isolated to tuned networks mounted on appli-

cable turret tuner segment (fig. 58).

Defective oscillator tuned network consisting of C11,

V2 mixer, signal injection

615 kc (center of band 2

C12, C13, R3 and T5 on band 2 tuner segment Z2

grid, pin 7 (fig. 47).

frequency range)

(fig. 58).

Defective amplifier plate coupling network consisting of

V1 rf amplifier plate, pin

615 kc

C14, C15, C16, R8, and T6 on band 2 tuner segment

22.

Defective input tuned network cousisting of C17, C18,

Front-panel SIGNAL, IN-

615 kc

and T7 on band 2 tuner segment 22.

PUT jack J705 (fig. 78).

Defective oscillator tuned network consisting of C19,

V2 mixer, signal injection

1.485 mc (center of band

C20, C21, R4, and T8 on band 3 tuner segment 23

grid, pin 7 (fig. 47).

3 frequency range)

(fig. 58).

Defective amplifier plate coupling network consisting

V1 amplifier plate, pin 1.

1.485 mc

of C22, C23, C24, and T9 on hand 3 tuner segment

Z3.

Defective input tuned network consisting of C25, C26,

Frout-panel SIGNAL. IN-

1.485 mc

PUT jack J705 (fig. 78).

and T11 on band 3 tuner segment 23; or trouble

between contact number 8 on turret tuner segment and

corresponding wiper 8 on rf tuner chassis (fig. 56).

Lack of proper contact between these terminals may

prevent test signal of approximately 1.6 mc (same

frequency as for 1,600-kc if. amplifier) from

heterodyning with oscillator V3.

Defective oscillator tuned network consisting of C27,

V2 mixer, signal injection

3.65 mc (center of band

C28, C29, R5, and T12 on bad 4 tuner segment 24

grid, pin 7 (fig. 47).

4 frequency range)

(fig. 58).

Defective amplifier plate coupling network consisting

V1 rf amplifier plate, pin 1.

3.65 mc

of C31, C32, and T13 on band 4 tuner segmeut 24.

Defective input tuned network consisting of C33, C34,

Frout-panel SIGNAL IN-

3.65 mc

PUT jack J705 (fig. 78).

and T14 on band 4 tuner segment 24.

Defective oscillator tuned network consisting of C35,

V2 mixer, signal injection

8.95 mc (center of had

C36, C37, R6, and T15 on band 5 tuner segment Z5

grid, pin 7 (fig. 47).

5 frequency range)

(fig. 58).

Defective amplifier plate coupling network consisting

V 1 rf amplifier plate, pin 1.

8.95 mc

of C38, C39, C40, and T16 on hand 5 tuner segment

25.

157