Uniden 2020 - User Manual

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Instruction Manual33 pages

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Summary

ACCESSORY CIRCUITS ALIGNMENT

NOISE BLANKER Adjustment

Procedure for adjusting the noise blanker circuit.

MARKER OSCILLATOR ADJUSTMENT

Procedure for adjusting the marker oscillator.

ALC METER ADJUSTMENT

Adjustment Procedures

Step-by-step guide for ALC meter adjustment.

RX RF UNIT ALIGNMENT

IF UNIT ALIGNMENT

Coil Adjustment.

Procedure for adjusting coils in the IF unit.

Carrier Balance Adjustment.

Procedure for adjusting carrier balance in the IF unit.

Modulator Output Coil Adjustment

TRANSMITTER RF CIRCUITS ALIGNMENT

RF output meter adjustment

Adjustment Procedure.

Procedure for adjusting the RF output meter.

LOCAL OSCILLATOR CIRCUITS ALIGNMENT

Oscillator Frequency Adjustment.

LOCAL OSCILLATOR UNIT ALIGNMENT.

Xtal Oscillator Output Adjustment.

Xtal Oscillator Frequency Adjustment.

VCO Buffer Amplifier Adjustment.

Summary

ACCESSORY CIRCUITS ALIGNMENT

NOISE BLANKER Adjustment

Procedure for adjusting the noise blanker circuit.

MARKER OSCILLATOR ADJUSTMENT

Procedure for adjusting the marker oscillator.

ALC METER ADJUSTMENT

Adjustment Procedures

Step-by-step guide for ALC meter adjustment.

RX RF UNIT ALIGNMENT

IF UNIT ALIGNMENT

Coil Adjustment.

Procedure for adjusting coils in the IF unit.

Carrier Balance Adjustment.

Procedure for adjusting carrier balance in the IF unit.

Modulator Output Coil Adjustment

TRANSMITTER RF CIRCUITS ALIGNMENT

RF output meter adjustment

Adjustment Procedure.

Procedure for adjusting the RF output meter.

LOCAL OSCILLATOR CIRCUITS ALIGNMENT

Oscillator Frequency Adjustment.

LOCAL OSCILLATOR UNIT ALIGNMENT.

Xtal Oscillator Output Adjustment.

Xtal Oscillator Frequency Adjustment.

VCO Buffer Amplifier Adjustment.

This document outlines the alignment procedures and technical specifications for the Uniden 2020, a device that appears to be a transceiver or a similar radio communication unit, given the references to RF, IF, transmitter, receiver, and various frequency bands. The manual provides detailed instructions for adjusting different circuits and measuring voltages, indicating a focus on precise calibration and maintenance.

Function Description:

The Uniden 2020 is a radio communication device that includes both receiver and transmitter functionalities, along with various auxiliary circuits for signal processing and control. Key functional blocks include:

Noise Blanker: A circuit designed to reduce impulse noise, which is common in radio communication. Its adjustment ensures optimal noise suppression.
Marker Oscillator: This generates a precise frequency signal, likely for calibration or frequency reference purposes. Its alignment ensures accuracy.
R.I.T. (Receiver Incremental Tuning) Circuit: Allows for fine-tuning of the receiver frequency independently of the transmitter, useful for adjusting to slightly off-frequency signals without affecting the transmit frequency.
S-Meter: An indicator that displays the strength of the received signal. Its calibration ensures accurate signal strength readings.
ALC (Automatic Level Control) Meter: Monitors and controls the output power of the transmitter, preventing overmodulation and ensuring a clean signal.
Receiver RF Unit: Handles the initial stages of signal reception, including tuning and filtering.
IF (Intermediate Frequency) Unit: Processes the received signal at a fixed intermediate frequency, where most of the signal amplification and filtering occur.
Transmitter RF Circuits: Generate and amplify the radio frequency signal for transmission.
PA (Power Amplifier) Idling Current Adjustment: Sets the quiescent current for the power amplifier, crucial for efficient operation and minimizing distortion.
Generator Unit: Likely responsible for generating various internal signals or frequencies required for the transceiver's operation.
Modulator Output Coil: Adjusts the output of the modulator, which impresses the audio signal onto the RF carrier.
Balanced Modulator: A key component in SSB (Single Sideband) transmission, responsible for suppressing the carrier frequency.
AM Modulation: Handles Amplitude Modulation for voice or data transmission.
Power Supply (AVR Unit): Provides stable DC voltages to various parts of the transceiver.
Local Oscillator Circuits (VFO Unit, PLL Unit, Local Oscillator Unit): Generate the necessary frequencies for mixing with incoming or outgoing signals, enabling tuning across different bands. These units include a Variable Frequency Oscillator (VFO) and Phase-Locked Loop (PLL) circuits for frequency stability and synthesis.

Important Technical Specifications:

While specific numerical specifications like power output or sensitivity are not explicitly listed in the provided excerpts, the document details various frequencies and voltage levels that are critical for the device's operation and alignment.

Frequencies:
- Noise Blanker/Marker Oscillator: 14.200 MHz, 25.000 KHz.
- R.I.T. Circuit: 1,000 Hz beat frequency.
- S-Meter: 14.200 MHz signal for calibration.
- ALC Meter: 14.2 MHz for transmitter tuning, audio frequencies of 1,900 Hz and 2,300 Hz for two-tone signal generation.
- Receiver IF Trap Coil: 6.187 MHz.
- Receiver Tuning Coils: Covers bands like 3.5 MHz, 7.0 MHz, 14.0 MHz, 21.0 MHz, 28.5 MHz, and 15.0 MHz.
- IF Tuning Coils: 14.200 MHz.
- Generator Unit: 6,187.000 kHz (USB), 6,187.750 kHz (TUNE).
- Modulator Output Coil: 14.2 MHz.
- Balanced Modulator/AM Modulation: 14.2 MHz output, 1,500 Hz audio input.
- Transmitter RF Circuits: Covers bands like 3.600 MHz, 7.100 MHz, 14.200 MHz, 21.200 MHz, 28.500 MHz.
- Feedback Neutralizing: 21.2 MHz.
- VFO Unit: 9,038 kHz and 9,138 kHz.
- PLL Unit: 16.000 MHz (VCO unlocked-oscillation).
- Local Oscillator Unit (PC-092): Xtal Oscillator Output Adjustment frequencies range from 25.525 MHz to 51.525 MHz, covering bands from 3.5 MHz to 29.5 MHz.
Voltages:
- Noise Blanker: Minimum meter readings at Q119 collector.
- Modulator Output Coil: 0.2V r.m.s. (max VFVM indication), 0.3V r.m.s. (max meter indication).
- Power Supply (AVR Unit): 8.2V DC, 6V DC (5.5-6.5V), 5V DC (5.0+0.2/-0.1V), R.I.T. Power Source (1.3V ±0.1V).
- Local Oscillator Unit (PC-092): 1.5V r.m.s. (Xtal Oscillator Output), 0.7 – 1.3V r.m.s. (Bandpass Filter Output), 0.4 – 0.5V r.m.s. (VFO Output).
- PLL Unit: 0.5V r.m.s. (Bandpass Amplifier).
- Voltage Measurements (Tubes): Various DC and AC voltages are specified for different pins of tubes like V251 (12BY7A), V1001/V1002 (6146B), including values like -3.2V, -16.5V, 0.29V, -50V, 280V, 325V, 750V, 900V, 430V, 460V.
- Voltage Measurements (Transistors & FETs): Detailed DC voltages (E/S, C/D, B/G1, G2) are provided for numerous transistors (e.g., 2SC735Y, 2SC784R, 2SC372Y, 2SK35BL, 2SK19GR, 2SC380Y, 2SA495Y, 2SC11730, 2SC1682) and FETs across different units (L.O., RX-RF, TX-RF, IF, AF, GE, AVR, VFO, OPR, RF-PA, PLL). These values range from 0V to 12.0V.
- Voltage Measurements (ICs): DC voltages are specified for various pins of ICs like MC1496 and TA7063P, ranging from 0V to 12.0V.
- RF Voltage Measurements (PLL Unit): Peak-to-peak voltages are specified for different points, e.g., 2.2V P-P, 0.8V P-P, 240mV P-P, 1.6V P-P, 7.5V P-P, 1.4V P-P, 5.0V P-P.
Current: PA Idling Current: 200 mA (IK reading).

Usage Features:

The manual primarily focuses on alignment and maintenance, but it implicitly reveals several usage features:

Mode Selection: Supports USB (Upper Sideband), LSB (Lower Sideband), AM (Amplitude Modulation), and TUNE modes.
Frequency Tuning: Features a main dial, BAND SWITCH, and SEGMENT SWITCH for selecting and fine-tuning frequencies across various bands (e.g., 3.5 MHz to 28.5 MHz, 15.0 MHz).
RF Gain Control: Allows adjustment of the receiver's sensitivity.
RF ATT (Attenuator) Knob: Likely reduces the strength of strong incoming signals to prevent receiver overload, and also activates the marker oscillator when pulled out.
PRESELECT Knob: Used for pre-selection filtering, enhancing receiver performance by reducing out-of-band interference.
MIC GAIN CONTROL: Adjusts the microphone input level for the transmitter.
CARRIER CONTROL: Adjusts the carrier level, especially important for AM and SSB modes.
PLATE and LOAD Controls: Used for tuning the final amplifier stage of the transmitter to match the antenna impedance for maximum power transfer.
STANDBY SWITCH: Controls the operational state of the transceiver (e.g., MANU, PTT).
METER SWITCH: Selects what the meter displays (e.g., ALC, PWR, IK).
FUNCTION SWITCH: Controls overall operational modes (e.g., INT, R. EXT).
R.I.T. SWITCH: Activates or deactivates the Receiver Incremental Tuning.
N.B. SWITCH: Activates or deactivates the Noise Blanker.
AGC SWITCH: Controls Automatic Gain Control for the receiver (e.g., FAST).
External Speaker Jack: Allows connection of an external speaker or dummy load.
RF POWER AMP SWITCH: Controls the RF power amplifier.

Maintenance Features:

The document is essentially a maintenance guide, detailing precise steps for alignment and troubleshooting. Key maintenance aspects include:

Test Equipment Requirements: Specifies the need for a DC Voltage Meter, Frequency Counter, Standard Signal Generator (SSG), RF Power Meter, AF Milli-volt Meter (mV), Audio Generator (AG), Oscilloscope, RF Voltage Meter (RF VTVM), and Sweep Generator. This indicates that specialized tools are necessary for proper servicing.
Circuit Alignment Procedures: Comprehensive step-by-step instructions are provided for aligning various circuits, including:
- Noise Blanker Adjustment (L139, L140).
- Marker Oscillator Adjustment (C753).
- R.I.T. Circuit Alignment (R665, R664).
- S-Meter Adjustment (R387, R389, R392).
- ALC Meter Adjustment (R388).
- Receiver IF Trap Coil Alignment (L01, L207).
- Receiver Tuning Coil Alignment (L201-L213).
- Receiver IF Tuning Coil Alignment (L214-L218).
- IF Unit Coil Adjustment (L351-L354).
- Carrier Balance Adjustment (R374, C370).
- Transmitter RF Tuning Coil Adjustment (L251-L263).
- RF Output Meter Adjustment (R08).
- Feedback Neutralizing (C1037).
- Generator Unit Alignment (L510, C541, C542).
- Modulator Output Coil Adjustment (L501, L504).
- Balanced Modulator Alignment (R530).
- AM Modulation Adjustment (R509).
- VFO Unit Oscillator Frequency Adjustment (L702, C707).
- VFO Unit Output Voltage Adjustment (L706, L707).
- PLL Unit VCO Unlocked-oscillation Frequency Adjustment (L801).
- PLL Unit Bandpass Amplifier Alignment (L804-L807).
- Local Oscillator Unit Xtal Oscillator Output Adjustment (L101-L110).
- Local Oscillator Unit Xtal Oscillator Frequency Adjustment (C116-C125).
- Local Oscillator Unit VCO Buffer Amplifier Adjustment (L121, L122).
- Local Oscillator Unit Bandpass Filter Adjustment (L123-L136).
Voltage Measurements: Detailed tables for voltage measurements on tubes, transistors, FETs, and ICs serve as a crucial diagnostic tool for identifying faulty components or incorrect operating conditions.
Waveform Diagrams: The inclusion of waveform diagrams for various points in the PLL and Marker circuits (e.g., OB15, OB13, OB12, OB11, OB10, Q752, Q753, J751) is invaluable for verifying correct signal shapes and timing during troubleshooting.
Service Extension Boards: The manual mentions using "SERVICE EXTENSION BOARD" for IF UNIT and GENERATOR UNIT, indicating a design that facilitates modular testing and repair.
Safety Precautions: Explicit warnings about high voltage and the need for quick adjustments during transmitter tuning highlight safety considerations for technicians. The caution about using insulated screwdrivers for specific adjustments further emphasizes safe practices.
Component Identification: References to specific component numbers (e.g., L139, C753, R665, Q119, J751) allow technicians to locate and adjust the correct parts on the circuit boards.

In summary, the Uniden 2020 is a sophisticated radio transceiver requiring meticulous alignment and maintenance. The provided manual serves as a comprehensive guide for technicians, ensuring the device operates within its specified parameters for optimal performance.