View and Download Icom IC-T81E service manual online. JB 1C 103K-T-A C3850 S.CERAMIC ECUE1E102KBQ C7820 S.CERAMIC. INSTRUCTION MANUAL WARNING. LULAR RADIO TELEPHONE SERVICE SIGNALS IS PROHIBITED UNDER FCC RULES AND FEDERAL LAW. I Thank you for purchasing this Icom product. The IC-E90 MULTI BAND TRANSCEIVER is designed and built with Icom’s superior technology and craftsmanship.

• SERVICE MANUAL MULTIBAND FM TRANSCEIVER. • SYMBOL U.S.A. USA-1 IC-T81A Australia S.E.Asia Europe IC-T81E U.K. Italy To upgrade quality, all electrical or mechanical parts and internal circuits are subject to change without notice or obligation. DANGER NEVER connect the transceiver to an AC outlet or to a DC power supply that uses more than 16 V. • TABLE OF CONTENTS SECTION SPECIFICATIONS SECTION INSIDE VIEWS SECTION DISASSEMBLY INSTRUCTIONS SECTION CIRCUIT DESCRIPTION RECEIVER CIRCUITS..4-1 TRANSMITTER CIRCUITS. • SECTION 1 SPECIFICATIONS GENERAL • Frequency range Version 145 MHz 440 MHz 1200 MHz 91.5 MHz (RX only) 50 MHz TX: 144 – 148 TX: 430 – 450 U.S.A.

1240 – 1300 76 – 107.995 50 – 53.995 RX: 118 – 173.995 RX: 400 –. • RECEIVER • Receiver system: Double-conversion superheterodyne • Intermediate frequency: 1st 69.45 MHz (13.35 MHz: WFM) 2nd 450 kHz • Sensitivity* (except spurious points; typical values) Band 50 MHz 0.56 µV – 0.18 µV 144 MHz 0.18 µV – –. • SECTION 2 INSIDE VIEWS • LOGIC UNIT BOTTOM VIEW Crystal filter (X1: CR-639 5.039MH) (IC1: M38267M8LGP) AF mute switch (Q361: 2SJ364) AF volume (IC202: M5222FP) AF power amplifier IF IC (IC201: TA7368F) (IC701: TA31136FN) • RF UNIT BOTTOM VIEW TOP VIEW Power amplifier (Q922: 2SK3075) Drive amplifier. • SECTION 3 DISASSEMBLY INSTRUCTIONS • REMOVING THE CHASSIS PANEL • REMOVING THE SHIELD PLATE 1 Remove 1 knob A, and unscrew 1 nut B. 1 Unsolder 10 points, F, to separate the shield plate and 2 Unscrew 2 screws C. • SECTION 4 CIRCUIT DESCRIPTION 4-1 RECEIVER CIRCUITS Thus, transmit signals are blocked from entering the receiv- er circuits. The antenna switching circuit employs a 1/4 4-1-1 DUPLEXER CIRCUIT (RF UNIT) type diode switching system.

Drivers license generator california map. The passed signals are then The transceiver has a duplexer (low-pass and high-pass fil- applied to each RF amplifier circuit. • • RF signals WFM band • 50, 144, 440 and 1200 MHz band The WFM band signals are applied to the RF amplifier The applied RF signals are mixed with 1st LO signals at the (Q201) via the tunable band-pass filter (D202).

The ampli- 1st mixer (IC601) to produce a 69.45 MHz 1st IF signal. • 4-1-8 2ND IF AND DEMODULATOR CIRCUITS Even when the squelch is closed, the AF mute switch (Q361) opens at the moment of emitting beep tones. (RF AND LOGIC UNITS) The 2nd mixer circuit converts the 1st IF signal to the 2nd IF •. • The amplified signal is passed through the antenna switch- (3) 440 MHz band ing circuit (D101 and D102), low-pass filters and high-pass The signals from the limiter amplifier (RF unit; IC301) filters. The signal is applied to the antenna connector.

Changes the reactance of a diode (VCO unit. • The APC sensor (R911) detects driving current from the The applied signal is divided by serial data from the CPU (N- drive voltage at the YGR (Q138), drive (Q921) and power data) and phase-detected with the divided reference fre- (Q922) amplifiers.

The detected current is converted into DC quency (5 kHz) at the phase detector section in the PLL IC. • 4-5 PORT ALLOCATIONS 4-5-2 I/O EXPANDER IC (RF UNIT; IC3) 4-5-1 I/O EXPANDER IC (RF UNIT; IC2) Port Port Description Description number name number name Outputs VHVCO3 regulator control Outputs 300 MHz band RX regulator signal. Control signal. Outputs VLVCO3 regulator control Outputs AM mode regulator control signal. • 4-5-3 CPU (LOGIC UNIT; IC1) Port Port Description Description number name number name Input port for the over-voltage detec- CLONEIN Input port for the cloning signal. Tion from connected battery pack or Outputs T4 regulator control signal.

External power supply. High: While transmitting. • SECTION 5 ADJUSTMENT PROCEDURES 5-1 PREPARATION ‘ ‘ REQUIRED TEST EQUIPMENT EQUIPMENT GRADE AND RANGE EQUIPMENT GRADE AND RANGE Output voltage: 13.5 V DC DC voltmeter Input impedance: 50 kΩ/V DC or better DC power supply Current capacity: 3 A or more Frequency range: 300–3000 Hz.