Realistic RadioShack TRC-410 Service Manual

Service

CB 40-CHANNEL TRANSCEIVER

TRC-410

Catalog Number • 21-1504

CUSTOM MANUFACTURED FOR RADIO SHACK MA DIVISION OF TANDY CORPORATION

CONTENTS

SPECIFICATIONS

1.
BLOCK DIAGRAM

2.
ALIGNMENT INSTRUCTIONS

3.
FREQUENCIES GENERATED AND MIXED TO OBTAIN EACH CHANNEL

4.
TRANSISTOR LEAD IDENTIFICATION AND IC INTERNAL CONNECTION .. 10 - 11

5.

6.

TROUBLESHOOTING

7.

TRANSISTOR AND IC VOLTAGE CHART
PRINTED CIRCUIT BOARD (TOP VIEW)

8.
PRINTED CIRCUIT BOARD (BOTTOM VIEW)

9.
ELECTRICAL PARTS LIST

10.
EXPLODED VIEW PARTS LIST

11.
SCHEMATIC DIAGRAM

12.
EXPLODED VIEW/DISASSEMBLY INSTRUCTIONS

13.

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3 - 4

5

6 - 9

9

12

13
14 - 15
16 - 17
18 - 21

21
22 - 23
24 - 25

1. SPECIFICATIONS

GENERAL SPECIFICATIONS

Description

Transmitter

Receiver
Communicating frequencies
Voltage operation

Temperature and Humidity range
Transmitter/Receiver switching

STANDARD TEST CONDITIONS

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Crystal controlled double conversion, superheterodyne system

Crystal controlled PLL synthesizer, amplitude modulation

All 40 CB channels (26.965 to 27.405 MHz)

(positive or negative ground vehicles)

C to + 60

°

—30

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12 — 16 V DC

C and 10% to 90%

°

Electronic

Battery supply voltage
Modulation
Receiver "outputpower

Receiver output impedance
Ant. load impedance of transmitter
Ambient conditions

temperature
humidity

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TRANSMITTER SPECIFICATIONS

Description

RF power output

Emission

Modulation capabilities
AMC Range at 1 kHz

Frequency accuracy
Spurious radiation & Harmonic

signal radiation ratio from fundamental

Current consumption

unmodulated

80% modulated
Envelope distortion
Hum and Noise level

Stability against variation of

antenna impedance

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13.8 V DC

1000 Hz, 30%

500 mW at external SP.

8 ohms, non-inductive

50 ohms, non-inductive

17 to 23°C

40 to 70%

Nominal

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. 4.0 watts (max.) . . . .... 3.6-4.4 watts

8A3
+90%, —95%

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40 dB

0 002% . .... . . . . . ...

—65 dB

1050 mA
1600 mA
10% max. 1000 Hz, 50% mod.
40 dB min. below max. mod.

Satisfactory when dummy antenna
is varied from 40 ohms to 200 ohms.

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Limit

> 30dB

0.005%

—60 dB

1400 mA
1950 mA

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RECEIVER SPECIFICATIONS

Description
Intermediate frequency

1st IF

2nd IF
Sensitivity for 500 mW output
Sensitivity at 10 dB S + N/N

Adjacent channel rejection
Image rejection (1st IF/2nd IF)
IF rejection ratio (1st IF/2nd IF)
Signal-to-Noise ratio

at 1 mV input

Distortion at 1 mV input,

50% mod. (500 mW out)
AGC Figure of merit at 50 mV input
Power output at 500 ,uV Input

Undistorted (10% THD)

Maximum
Electrical fidelity compared to 1000 Hz

450 Hz

2500 Hz
Cross modulation
Squelch
Current consumption (no signal)
"S" meter sensitivity to light 4th LED

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Nominal

10.695 MHz
455 kHz

0.25 ,uV

0.6 ,uV
60 dB
45 dB
70 dB

40 dB

90 dB

3.5 W

6.0 W

—5 dB
—5 dB

50 dB

190 mA

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10 ,uV

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3%

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Adjustable from 0.6 AN to 1 mV

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Limit

0.5 ,uV

1.2 AN
56 dB
35 dB
60 dB

34 dB

6%

70 dB

3.0 W

4.0 W

—6+3 dB
—6+3 dB

45 dB

280 mA

5 — 20 pV

OTHER ITEMS

Fuse

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General power requirement
Dimensions

Weight

NOTE: Nominal Specs represent the design specs; all units should be able to approximate these

— some will exceed and some may drop slightly below these specs. Limit specs represent the
absolute worst condition which still might be considered acceptable; in no case should a unit
perform to less than within any Limit spec.

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(H) 1-18/32"(40mm) x (W) 4-30/32"(125mm) x (D) 8-5/32"(207mm)

4

12 — 16 V DC

2 lb 2 oz. (1 kg)

2 Amp.

2. BLOCK DIAGRAM

3. ALIGNMENT INSTRUCTIONS

Base of

Q15

Bose of 017

A. PLL SECTION

1. Test Equipment Required
Frequency Counter

a.
b.

DC Power Supply (13.8 Volt, 2.5 Amp.)
DC Volt Meter (above 100 KQ/V)

c.

NOTE: Figure 1 provides test point and

alignment location information.

2. Alignment Procedure

STEP

1

2

3

4

5

6

MIC: Receive, POWER: "on", VOLUME: Optional, SQUELCH: Optional, Channel Selector: Optional.
Connect Frequency Counter to output

of CF-3 (Figure 2).
MIC: Transmit, Channel Selector: Channel 40.
Connect DC Volt Meter to R71/R72

(Figure 3).

MIC: Receive, Channel Selector: Channel 1.
Same as step 5.

OUTPUT INDICATOR

CONNECTION

017

CHANNEL

SQUELCH

VR 2

VOLUME

VR I

Figure 1

ADJUST

C75

015 L5

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TI I

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=,3 fiR72

C75

Output of CF3

J

3R71

CF3

T8

©I

1-10

T5

ADJUST FOR

If the frequency is not 10.240 MHz ± 400 Hz,

5

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L4

O

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R2I

T4

T3

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04

VR4

D VR5

oo

Base of 04 1

change value of C75 (18-39 pF).

T8

Alignment of VCO

Adjust for 6.0 Volt indication on DC
Volt Meter.

Check for indication on DC Volt Meter; must be 2.5-3.5 Volt.

If DC Volt Meter does not indicate 2.5-3.5 Volt, readjust T8
(return to step 4).

TI

T

al

ANT. JACK

EXT .SP. JACK

Frequency Counter

output of CF-3

Figure 2

B. TRANSMITTER SECTION

1. Test Equipment Required
RF Output Power Meter

a.

50 Ohm Load (non-inductive)

b.
c.

RF Attenuator

d.

Oscilloscope

e.

Audio Generator

NOTE: Figure 1 provides test point and alignment location information.

2. Alignment Procedure

STEP

1
2

3

4

SIGNAL SOURCE

CONNECTION

Set Channel Selector to Channel 18.
Disconnect R95 (or short base of Q17 to ground with 0.01 ,u F).

f.

DC Power Supply (13.8 Volt, 2.5 Amp.)

g.

Field Strength Meter (or Spectrum Analyzer)

h.

Frequency Counter

i.

Coupler

OUTPUT INDICATOR

CONNECTION

Connect RF V.T.V.M. to base
of Q15 (Figure 4).

Figure 3

ADJUST

T10

T11

R7I / R 72

DC VOLT METER

I

Base of QI5

Figure 4

ADJUST FOR

Alignment of
Pre-driver Stage

Adjust for maximum
indication on RF V.T.V.M.

RF V.T.V.M.