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IGNITION NOISE INTERFERENCE 

 

CHAPTER 3 OPERATION

 

With weak signals, you may experience interference of the signal by background 

noise. This radio has NB and ANL circuits which will help reduce background noise 
from sources such as your ignition system. However, background electrical noise may 
come from several sources and all noise may not be eliminated. With extremely weak 
signals, you can operate this radio with the engine turned off, which should improve 
reception. If the ignition noise level is too high to allow proper operation under most 
conditions, you should have your installation of the radio checked by a qualified 
technician. 

 

CONTROL FUNCTIONS 
FRONT PANEL 

 

 

- 4 - 

 

ANTENNA 

This radio has a jack in the rear for a standard PL-259 antenna plug. If you are 

looking for the most range for your transmission, use a vertically polarized, quarter-
wave length antenna. If antenna height is a problem, you may use a shorter, loaded-type 
whip antenna although you can expect some loss of transmission range. 
To improve performance, your antenna should be matched to your radio. Your antenna 
can be adjusted so that it matches your radio. 

    

EXTERNAL SPEAKER 

The external speaker jack (EXT SP.) on the rear panel is used for remote receiver 

monitoring. The external speaker should have 8 ohms impedance and be able to handle 
at least 4 watts. When the external speaker is plugged in, the internal speaker is 
disconnected. 
 

 

PUBLIC ADDRESS 

1. MICROPHONE 

JACK:

 Used to connect microphone for voice source. 

To use the Public Address (PA) function, first connect an external speaker to the PA. 

SP. Jack on the rear of the radio. See the above specifications for a proper external 
speaker. Keep the speaker away from the microphone to avoid acoustic feedback. 

 

2. 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. 

 

 

3. 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 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. 

+ 10KH z

VO L     SQ

B

A

O FF

O FF

TB

TB     PW R

M IC  G A IN      RF G AIN

G

H

C

D

E

F

SW R

RX  / TX

B I

G   R I

G   S E R I

E S

EC H O      TIM E

M IC

1

2 3 4 5 6 7

8

9

10

11 12 13 14

15 16 17 18 19 20 21 22

+6

0

dB

M O D

S

9

20

10

5

1

SW R

PW R

0

1.5

2

4 0

5

1

3

20

6 0

7

4 0

30

50

3

M

AX

+20

8 0

+4

0

10 0

%

N B/A N L

+ 10KH z

N B/A N L

O FF

M O D

PW R

PA

FM

SW R

A M

O FF

D IM

M ED

EC H O

BRIG H T

 

4. MIC GAIN CONTROL:

 Adjusts 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 
functions as the volume control. 

 

 

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Summary of Contents for DX 48T

Page 1: ...TENTS PAGE CHAPTER 1 Specifications 2 CHAPTER 2 Installation 3 Installing The Radio 3 Ignition Noise Interference 4 Antenna 4 External Speaker 4 Public Address 4 CHAPTER 3 Operation 5 Front Panel 5 Re...

Page 2: ...installed Make sure nothing will interfere with either the radio or the mounting bolts Mark and then drill holes for the mounting bracket 2 Most radio antennas come equipped with a PL 259 plug Connect...

Page 3: ...S 1 MICROPHONE JACK Used to connect microphone for voice source To use the Public Address PA function first connect an external speaker to the PA SP Jack on the rear of the radio See the above specifi...

Page 4: ...allows the user to monitor signal strength RF output power SWR level and AM modulation level 22 RX TX LED The red LED indicates the unit is in the transmit mode The green LED indicates the unit is in...

Page 5: ...SQ 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 the weaker signals will not be heard 1 ANTENNA This jack ac...

Page 6: ...and fourth is for receiving control The microphone should provide the functions shown in the schematic below 4 WIRE MIC CABLE Pin Number Mic Cable Lead 1 Audio Shield 2 Audio Lead 3 Transmit Control 4...

Page 7: ...ure 2 are pushed back onto the microphone cable before starting to solder If the washer is not captive to the pin receptacle body make sure that it is placed on the threaded portion of the pin recepta...

Page 8: ...Please include a note with a detailed description of the symptoms This is important because it will help the technician who works on your radio to locate your problem Intermittent problems are easily...

Page 9: ...Printed in Taiwan AT0949011D...

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