Realistic htx 202 service manual

Page 1

ervice Mama

HTX-202
2-Meter Amateur VHF ~FM Transceiver
Catalog Number: 1 9-1 1 20

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Contents
Specifications .................... . .................................. 2
Disassembly Instructions ............................................... 4
Block Diagram .......................... , ............................. 7
Theory ot Operation ........................................... 1 ..... 11
Alignment Instructions .................. .............................. 17
Troubleshooting Hints ................................................ 22
Error Display ....................................................... 23
Wiring Diagram . . ............................................ ...... 24
Printed Circuit Board Views (Top and Bottom! .............................. 25
Exploded View ..................................................... 36
Exploded View Parts List .............................................. 37
Electrical Parts List .................................................. 40
Semiconductor Voltage Chart ...................... , .................... 55
Semiconductor Lead Identification ....... . ............ .................... 5 9
IC Internal Connection ................................................ 63

Schematic Diagrams ................................................. 69

° I992 Tandy Corporation.
All Night. Round.
Realistic is a registered trademark used by Tandy Corporation.

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SPECIFICATIONS

General '

Transmitter .......................................... PLL synthesizer, Frequency Modulation
Receiver .................. . PLL synthesizer. superheterodyne system
Communication Frequency Range ................................................ I44~I4BMH1 (SKHz step)
Operating Voltage ................................................................. 6~ 14V DC (negative groundl
Temperature and Humidity range ............... 14°F~ 140°F (-10°C~ +60°Cl and 10%~90%
Transmitter/Receiver switching ............................................................................ Electrical

Standard Test Conditions

Battery supply voltage . . 7.2V DC
Modulation ...................................... SIG-ll
Receiver output Impedance ...................................... 8 ohms, nonainductive .
ANT. load impedance of transmitter ........... 50 ohms, non-inductive

Ambient conditions:

Temperature . 63°F ~ 91°F (17": ~33°Cl

Humidity ...........................
Receiver
Description Nominal Limit
Intermediate Frequency

lst IF .. 21.4MHz

2nd IF .......................................................... 455 KHz
Sensitivity:

12 d8 SINAD ............ _. ........................................ 0.2,.v 0.25,.v

20 do No. ......................................................... 0.35pv 0.4,.v
Squelch Sensitivity:

Threshold .......................................................... 0.1pV 0.2uV

Tight ................... t ...................... 4- luv
Spurious Response Attenuation .......... 6MB
Intermodulation Attenuation .............. 60GB
Adjacent Channel Rejection (25KHzl 6MB
Modulation Acceptance Bandwidth ..... .. 7.5KHz
Hum and Noise ..................................................... 50dB 40dB
Audio Output Power (10% THDI:

7.2V DC ..................................... 0.25W

9V DC ..................... . ............ CLAW

0.7W

Audio Distortion 2% ' 10%
Audio Response . ............. -6dB/oct + II ads, Gdaloct
Current Drain:

Standhby without Power Save .............................. 35mA 45mA

Stand-by Powar Save 25mA 30mA
CTCSS Sensitivity .. 0.15uV 0.2uV
DTMF Squelch Sensitivity ................................. . ..... 0.2pV 0.25av