Icom IC-2720H Service Manual

for the IC-2720H DUAL BAND FM TRANSCEIVER at the time of publication DANGER NEVER connect the transceiver to an AC outlet or to a DC power supply that uses more than 16 V. This will ruin the transceiver. DO NOT expose the transceiver to rain, snow or any liquids. DO NOT reverse the po ...

SECTION 1 SPECIFICATIONS SECTION 2 INSIDE VIEWS SECTION 3 DISASSEMBLY INSTRUCTIONS SECTION 4 CIRCUIT DESCRIPTION 4 - 1 RECEIVER CIRCUITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 - 1 4 - 2 TRANSMITTER CIRCUITS . . . . . . . . . . . . . . . . . . . . . . . . . . ...

SECTION 1 SPECIFICATIONS All stated specifications are subject to change without notice or obligation. M GENERAL • Frequency range : LEFT SIDE RIGHT SIDE * 1Guaranteed 144.000 – 146.000 MHz only, * 2Guaranteed 144.000 – 148.000 MHz only, * 3Guaranteed 430.000 – 440.000 MHz only; * 4Guaranteed 440.000 – 450.000 MHz only * 5Not guaranteed range ...

• CONTROL UNIT (TOP VIEW) Key back light (DS14, DS15: LN1371G) LCD back light DS1-3, DS7-9: SML-010MT DS4-6, DS10-12: SML-020MLT Key back light (DS16, DS17: LN1371G) Key back light (DS15, DS18: LN1371G) Key back light (DS14, DS15: LN1371G) LCD back light DS1-3, DS7-9: SML-010MT DS4-6, DS10-12: SML-020MLT Key back light (DS1 ...

Dimmer +8V regurator (Q1: 2SC4116) +5V regurator (IC3: TA78L05F) Sub CPU (IC4: HD6473847RH) Reset IC (IC2: S-80945CLMC) Data comparator (IC1: TA75S01F) Mic amplifier IC5: TA75S558F Q15: 2SC4116 Dimmer circuit (Q6-Q13: 2SC4116) +8V regurator Q1: 2SC4116 Q3: 2SA1586 D1: MA8091 +5V regurator (IC3: TA78L05F) Control unit CPU ( ...

Œ Unscrew 8 screws A, and remove the cover.  Disconnect two cables B from J1 and J2007. Ž Remove the clip c. A A B C J2007 J1 G F G F H E MAIN UNIT J I  Unsolder 3 points E.  Unscrew 4 screws F. ‘ Unsolder 4 points G, and remove the cover H. ’ Unscrew 2 screws I. “ Unscrew 12 screws J, ...

Œ Remove 6 knobs A. A A  Unscrew 4 screws B, and remove the cover. Ž Remove the plate C, and remove CONTROL unit. B C CONTROL UNIT 3 - 2 ...

SECTION 4 CIRCUIT DESCRIPTION 4-1 RECEIVER CIRCUITS 4-1-1 TRIPLEXER AND RX BAND SWITCHING CIRCUITS (MAIN UNIT) The transceiver has a triplexer (low-pass and high-pass fil- ters) on the first stage from the antenna connector to sepa- rate the signals into VHF and UHF signals. The RF signals from the antenna connector are applied to the tripler or RX ban ...

The signals from the RX band swtiching circuits are then applied to the left side displayed 1st mixer circuit (IC1005, pin 6). 4-1-3 1ST MIXER AND 1ST IF CIRCUIT FOR LEFT SIDE DISPLAY (MAIN UNIT) The 1st mixer circuit converts the received RF signals to a fixed frequency of the 1st IF signal with a PLL output fre- quency. By changing the PLL frequency, ...