Icom IC-F3023T, IC-F3023S, IC-F3022T, IC-F3022S, IC-F3021S, IC-F3021T PLL Circuits, PLL IC Main Unit

Page 11

5-3 PLL CIRCUITS

5-3-1 VOLTAGE CONTROLLED OSCILLATORS (VCOs; MAIN UNIT)

VCO is an oscillator whose oscillating frequency is controlled by adding voltage (lock voltage).

This transceiver has 2 VCOs RX VCO (Q17, D9, D11, D33) and TX VCO (Q16, D10, D13, D34). The RX VCO oscillates the 1st LO signals, and the TX VCO oscillates the transmit signal.

• RX VCO

The output signals are amplifi ed by the buffer amplifi ers (Q15, Q29), and applied to the 1st mixer (Q6) via TX/RX switches (D16 is OFF, D17 is ON) and LPF (L46, C396, C397), to be mixed with the received signals to produce the 46.35 MHz 1st IF signal.

• TX VCO

The output signal is applied to the transmit amplifi ers via the buffer amplifi ers (Q15, Q29) and TX/RX switches (D16 is ON, D17 is OFF).

A portion of each VCO output is applied to the PLL IC (IC2, pin 8) via the buffer amplifi er (Q15), doubler (Q14), BPF (D31, D32, L32, C196, C197, C199, C200, C205) and LPF (L34, L36, C202–C204).

• PLL CIRCUITS

5-3-2 PLL IC (MAIN UNIT)

The PLL circuit provides stable oscillation of the transmit frequency and receive 1st LO frequency. The PLL output frequency is controlled by the divided ratio (N-data) from the CPU.

The VCO output signal from the LPF (L34, L36, C202–C204) is applied to the PLL IC (IC2, pin 8). The applied signal is divided at the prescaler and programmable counter according to the “SSO” signal from the CPU (IC22, pin 99). The divided signal is phase-compared with the reference frequency signal from the reference frequency oscillator (X2), at the phase detector.

The phase difference is output from pin 5 as a pulse type signal after being passed through the internal charge pump. The output signal is converted into the DC voltage (lock voltage) by passing through the loop filter (R94–R96, C16, C17, C146). The lock voltage is applied to the varactors (D9 and D33 of RX VCO, D10 and D34 of TX VCO) and locked to keep the VCO frequency constant.

If the oscillated signal drifts, its phase changes from that of the reference frequency, causing a lock voltage change to compensate for the drift in the VCO oscillating frequency.

TX VCO

 

 

D16

 

 

 

 

 

Buffer

to the transmit amplifiers

Q16, D10, D13,

D34

Q29

 



D17

D12

 

 

Buffer

 

to the1st IF circuits

 

 

RX VCO

Q15

 

 

×2

 

 

Q14

Q17, D9, D11, D33

 

 

PLL IC (IC2)

Loop

5

Charge

Programmable

Prescaler

8

BPF

filter

 

pump

divider

LPF

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

9

SCK

 

Modulation signals

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Phase

 

 

 

 

Shift register

10

SSO PLL control signals from the CPU (IC22)

from the D/A converter

 

 

 

 

 

 

 

 

 

detector

 

 

 

 

11

 

 

 

 

 

 

(IC12, pin10)

 

 

 

 

 

 

 

 

 

 

 

 

 

PLST

TCXO

 

 

 

 

 

 

 

 

 

 

 

 

 

 

7

 

 

 

 

 

 

 

 

 

 

 

 

 

 

15.3 MHz

 

 

 

 

 

 

 

Reference

 

 

1

 

 

 

 

 

 

 

 

 

X2

PLL unlock signal

 

 

 

 

 

 

 

 

counter

 

 

 

reference frequency signal

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

to the CPU (IC22, pin 34)

5 - 4

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Page 10 Page 12
Contents VHF FM Transceivers Repair Notes IntroductionOrdering Parts Table of Contents EUR Section SpecificationsPA Unit Section Inside ViewsMain Unit Removing the PA Unit Disassembly InstructionsRemoving the Chassis Unit Removing the Main UnitUT-108R UT-109R UT-110R Optional Unit InstallationRF Circuits Main Unit Antenna Switching Circuit PA UnitCircuit Description Receiver CircuitsModulation Circuits Main Unit Transmitter CircuitsMicrophone Amplifier Circuits Main Unit Squelch Circuits Main UnitOver Current Detection Circuit PA Unit Transmit Amplifiers PA UnitAPC Circuit PA Unit PLL IC Main Unit PLL CircuitsPower Supply Circuits CPU IC22 Port AllocationsStarting Software Adjustment Adjustment ProceduresBefore Starting Software Adjustment JIG Cables ConnectionPC Screen Exsample Frequency Adjustment Transmit Adjustment Convenient Receive AdjustmentMain Unit Parts ListOrder Description Location Order Description 16.3/10.3 PA UnitANT Unit PA Unit Connect UnitBC-160 Optional product ANT Unit Mechanical Parts and DisassemblyAccessories Chassis PartsMP2 C, MP12 C The shape is depending on the version Diodes Semiconductor InformationPA Unit TOP View Board LayoutsMain Unit TOP View ANT Unit TOP ViewANT Unit Bottom View Main Unit Bottom ViewConnect Unit Bottom View PA Unit Bottom ViewMain Unit Block Diagram28 6# Voltage DiagramsPA Unit BC-160 SectionPage 32, Kamiminami, Hirano-ku, Osaka 547-0003, Japan

IC-F3022T, IC-F3023T, IC-F3021S, IC-F3021T, IC-F3022S specifications

The Icom IC-F3023S, IC-F3022S, IC-F3021T, IC-F3021S, and IC-F3023T are part of Icom's robust lineup of mobile radios designed for reliable communication in diverse environments. These radios are renowned for their durability, advanced features, and user-friendly operation, making them ideal for organizations in public safety, security, and industrial sectors.

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One of the key characteristics across these models is their versatility in communication. They support multiple frequency bands and have programmable channels, allowing users to customize their communication preferences according to their operational needs. The IC-F3021T and IC-F3021S variants also support Trunked Operation which facilitates seamless communication across larger teams.

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In summary, the Icom IC-F3023S, IC-F3022S, IC-F3021T, IC-F3021S, and IC-F3023T radios are designed to meet the demands of professional users who require high-performance communication devices. With their rugged build, exceptional audio quality, and advanced features, these radios are invaluable tools in maintaining effective communication in any operational setting. Whether for construction sites, emergency services, or security details, these models offer the reliability and function that professionals need every day.
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