Ranger TR-127GK, TR-127DX User Manual

Communications, Inc.

REV. A

Dec. 2004

TR-127GK/DX

40 CHANNEL

AM CB MOBILE RADIO

Service Manual

TABLE OF

TR-127GK/DX

CONTENTS

PAGE

CHAPTER 1

SPECIFICATIONS

1.0 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1.1 Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1.2 Receiver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

CHAPTER 2

OPERATION

2.0 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2.1 Control & Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

2.2 Microphone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . … 7

2.3 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . … 7

2.4 Alternate Microphones And Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

CHAPTER 3

CIRCUIT DESCRIPTION

3.0 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

3.1 PLL Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 9

3.2 Receiver Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

3.3 Transmitter Modulation Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . … 9

3.4 Transmitter Amplifier Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

CHAPTER 4

ALIGNMENT

4.0 Required Test Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . … 11

4.1 Alignment Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

CHAPTER 5

MAINTENANCE

5.0 Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

5.1 Periodic Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 15

5.2 Fuse Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

CHAPTER 6

DIAGRAMS AND PARTS LIST

6.0 PCB Layout & Parts List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

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TR-127GK/DX

1.0 GENERAL

Model TR-127GK, TR-127DX
Channels 40
Frequency Range 26.965 – 27.405 MHz
Emission Modes AM
Frequency Control Phase Lock Loop (PLL) synthesizer
Frequency Stability 0.001 %
Operating Temperature Range
Antenna Impedance 50 Ohms
Input Voltage 13.8V DC
Antenna Connector Standard SO-239 type
Dimensions 7 1/4”(W) x 9”(D) x 2 1/4”(H)
Weight 3.4 lbs.

1.1 TRANSMITTER

RF Power Output AM : 4 watts
RF Transmit Modes AM
Spurious Emissions - 60dB
Audio Frequency Response 300 to 2500 Hz
Microphone Dynamic
Output Indicators Meter shows incoming signal strength, RF output

1.2 RECEIVER

Sensitivity For 10dB S/N
IF Frequency AM: 10.695 MHz 1st IF, 455 KHz 2nd IF
Image Rejection - 50dB
Adjacent Channel Selectivity - 60dB
RF Gain Control 45dB adjustable for optimum signal reception
Automatic Gain Control (AGC) Figure Of Merit 100mV for 10dB Change in Audio Output
Squelch
Noise Blanker RF type
Audio Output Power 2.5W @ 10% THD
Audio Frequency Response 300 to 2500 Hz
Built-in Speaker 8 Ohms, 4 Watts
External Speaker (Not Supplied) 8 Ohms, 4 Watts

(SPECIFICATIONS SUBJECT TO CHANGE WITHOUT NOTICE)

CHAPTER 1

SPECIFICATIONS

-30°C to +50°C

power, and SWR level. Transmit LED glows red
when transmitter is in operation.

< 1.0µV

Adjustable; threshold less than 0.5µV

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CHAPTER 2

TR-127GK/DX

9 14131210 11 181715 16

TR - 127

MIC GAIN

ANLS/RF

SWR

CAL OFF LOW

VOL SQ

OFF

OFF PA

TONECBNB CH19

SWR CALRF GAIN

OPERATION

TX/RX

NORMAL ANT

CLARIFY

1 6432578

Figure 2-1 Front Panel

2.0 INTRODUCTION

This section explains the basic operating procedures for the TR-127GK or TR-127DX mobile CB radio.

2.1 CONTROLS AND CONNECTIONS

2.1.1 FRONT PANEL

Refer to the above Figure 2-1 for the location of the following controls.

1. MICROPHONE JACK: Used to connect microphone for voice source.

2. MIC GAIN CONTROL: Adjust the microphone gain in the transmit and PA modes. This controls

the gain to the extent that full talk power is available several inches away from the microphone. In
the Public Address (PA) mode, the control function as the volume control.

3. ON/OFF VOLUME CONTROL: This knob controls the volume and power to the radio. To turn

radio on, rotate the knob clockwise. Turning the knob further will increase the volume of the
receiver.

4. SQUELCH CONTROL: This knob is used to eliminate background noise being heard through the

receiver, which can be disturbing when no transmissions are being heard through the receiver. To
use this feature, turn the knob fully counterclockwise and then turn clockwise slowly until the

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background noise is just eliminated. Further clockwise rotation will increase the threshold level
which a signal must overcome in order to be heard. Only strong signals will be heard at a maximum
clockwise setting.

5. RF GAIN CONTROL: This control is used to reduce the gain of the RF (receive) amplifier under

strong signal conditions.

6. SWR CAL CONTROL: This SWR CAL control allows the user to calibrate the SWR meter.

7. CLARIFY CONTROL: Allows tuning of the receive frequency above or below the channel

frequency.

8. CHANNEL SELECTOR: This control is used to select the desired transmit and receive channel.

9. FRONT PANEL METER: The front panel meter allows the user to monitor incoming signal

strength, RF output power and SWR level.

10. S-RF/CAL/SWR SWITCH: In the S-RF position, the meter will indicate the strength of the signal

being received, as well as the relative RF output of transmission. When calibrating the SWR meter,
you need to put this switch in the CAL position. To use the meter to measure the standing wave
ratio, turn the switch to the SWR position.

11. ANL/OFF SWITCH: In the ANL position, the Automatic Noise Limiter (ANL) in the audio

circuits is activated.

12. NB/OFF SWITCH: In the NB position, the Noise Blanker (NB) is activated. The NB is very

effective in eliminating repetitive impulse noise such as ignition interference.

13. PA/CB SWITCH: Select the mode of operation. In the PA position, the radio acts as public address

amplifier. Your voice will come out of the speaker that is plugged into the PA. SP. jack on the rear
panel. The radio does not operate when you are in the PA mode. In the CB position, the PA function
is disabled and the radio will transmit and receive on the speaker that is connected.

14. TONE SWITCH HI/LO: This switch changes tone quality in receive only. In LO position, bass is

increased and in HI position, treble is increased.

15. CH19/NORMAL SWITCH: Channel 19 switch is used for instant to information channel 19.

16. TX/RX LED: The red LED indicates the unit is in the transmit mode. The green LED indicates the

unit is in the receive mode.

17. ANT LED: This LED lights red when your SWR is higher than about 3:1. This is not an exact

indicator of 3:1 SWR, but it is an indication that you should check your SWR reading.

18. CHANNEL DISPLAY: The channel display indicates the current selected channel.

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REAR PANEL
Figure 2-2 represents the location of the following connections:

134

This device complies with part 15 of the FCC Rules.
Operation is subject to the condi tion that this device
does not cause harmful interference.

FCC ID : MEE−VX−129CN
MODEL NO. : TR−127
AM 40 CH

SERIAL NO. :

CB TRANSCEIVER

MADE IN CHINA

ANT.

EXT.SP. PA.SP.

+POWER−

2

Figure 2-2 Rear Panel

1. ANTENNA: This jack accepts a 50-ohm coaxial cable with a PL-259 type plug.

2. DC POWER: This jack accepts the 13.8V DC power cable with built-in fuse. The power cord

provided with the radio has a black and red wire. The black goes to negative and red goes to
positive.

3. EXT SP.: This jack accepts a 4 to 8 ohm, 5-watt external speaker. When the external speaker is

connected to this jack, the built-in speaker will be disabled.

4. PA SP.: This jack is for PA operation. Before operating, you must first connect a PA speaker (8

ohms, 4W) to this jack.

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2.1.3 FREQUENCY CHART

CHANNEL

CHANNEL FREQUENCY

(MHz)

CHANNEL

CHANNEL FREQUENCY

(MHz)

1 26.965 21 27.215
2 26.975 22 27.225
3 26.985 23 27.255
4 27.005 24 27.235
5 27.015 25 27.245

6 27.025 26 27.265
7 27.035 27 27.275
8 27.055 28 27.285
9 27.065 29 27.295

10 27.075 30 27.305
11 27.085 31 27.315

12 27.105 32 27.325
13 27.115 33 27.335
14 27.125 34 27.345
15 27.135 35 27.355

16 27.155 36 27.365
17 27.165 37 27.375
18 27.175 38 27.385
19 27.185 39 27.395
20 27.205 40 27.405

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2.2 MICROPHONE

The push-to-talk switch on the microphone controls the receiver and transmitter. Press the switch and
the transmitter is activated, release switch to receive. When transmitting, hold the microphone two
inches from your mouth and speak clearly in a normal voice. This transceiver comes complete with a
low impedance dynamic microphone.

2.3 OPERATION

2.3.1 PROCEDURE TO RECEIVE

1. Be sure that the power source, microphone and antenna are connected to the proper connectors
before going to the next step.

2. Turn VOL knob clockwise to apply power to the radio.

3. Set the VOL to a comfortable listening level.

4. Set the MODE switch to the desired mode.

5. Listen to the background noise from the speaker. Turn the SQUELCH knob slowly clockwise until
the noise just disappears. The SQUELCH is now properly adjusted. The receiver will remain quiet
until a signal is actually received. Do not advance the control too far or some of weaker signals will
not be heard.

6. Set the CHANNEL selector switch to the desired channel.

7. Set the RF GAIN control fully clockwise for maximum RF gain.

8. Adjust the CLARIFY control to optimize AM signals.

2.3.2 PROCEDURE TO TRANSMIT

1. Select the desired channel of transmission

2. Set the MIC GAIN control fully clockwise.

3. If the channel is clear, depress the push-to-talk switch on the microphone and speak in a normal
voice.

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2.4 ALTERNATE MICROPHONES AND INSTALLATION

For best results, the user should select a low impedance dynamic type microphone or a transistorized
microphone. Transistorized type microphones have a low output impedance characteristic. The
microphones must be provided with a four-lead cable. The audio conductor and its shielded lead
comprise two of the leads. The third lead is for transmit control and the fourth is for receiving control.

The microphone should provide the functions shown in the schematic below (Figure 2-3).

4 WIRE MIC CABLE

Pin Number Mic Cable Lead

1 Audio Shield
2 Audio Lead
3 Transmit Control
4 Receive Control

Figure 2-3 Your Transceiver Microphone Schematic

Figure 2-4 Microphone plug and pin numbers viewed from rear of pin receptacle.

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