MFJ-269D SWR Analyzer Schematic Diagrams
This document presents the schematic diagrams for the MFJ-269D SWR Analyzer, a versatile instrument for measuring radio frequency (RF) parameters across HF, VHF, and UHF bands. The schematics detail various circuit sections, including voltage processing, oscillator, signal switching, prescaler, and frequency tripling.
General Information
Resistance values are in Ohms. Capacitance values are in microfarads unless otherwise specified.
Manufacturer: MFJ Enterprises Inc.
Model: MFJ-269D (Revision 8)
Document Date: August 11, 2020
Page 2: Voltages Processing
This section of the schematic illustrates the voltage processing and regulation circuits. It includes operational amplifiers (e.g., TLC2274C), diodes (e.g., MMBD770T1G), and an Analog-to-Digital Converter (ADC12138) for signal measurement and processing.
Key components include: TLC2274C (Quad Op-Amp), MMBD770T1G (Diodes), ADC12138 (ADC), various resistors (R1, R5, R10, R11, R20-R27, R34, R42-R46, R48-R50), capacitors (C7, C8, C10-C13, C24-C27, C116, C118, C119, C120), and variable resistors (VR1, VR2, VR3).
The diagram shows connections for power supply voltages like +4.7VSLP and references like VREF.
Page 3: Oscillator
This page details the oscillator circuits, crucial for generating the test signals used by the SWR analyzer. It features field-effect transistors (FETs) and bipolar junction transistors (BJTs) for oscillation and signal generation.
Key components include: MMBF J310 (FETs Q1, Q2), MMBT3904 (Q20), MMBT4403 (Q22), BFR183 (Q5), TLC2274C (Quad Op-Amp U4), various inductors (L1, L4, L6, L7, L8, L9, L17, L185, L20, L21), resistors, and capacitors.
The section also indicates reference voltages such as Vref = 1.24V and voltage readings like 4V <> VF = 2.48V. It shows switches (SW1, SW3) and relays (RLY1) for circuit configuration.
Page 4: Signal Switch, Prescaler
This section covers signal switching logic and frequency counting/prescaling circuits. It utilizes integrated circuits for digital functions and transistors for signal handling.
Key components include: MMBT4403 (Q19, Q23), BFR183 (Q7, Q8), MMBD914 (Diodes D3, D4), U11 (VAM-6+), U12 (74ALC74D), U14 (74AUC1G14), U15 (IC5219-), and various resistors and capacitors.
The schematic indicates connections for frequency counters (FREQ. CNTR.) and references signals like INT_S. It shows voltage levels such as 3.3V and +4.7VSLP.
Page 5: Tripler
This page illustrates the frequency tripler circuit, likely used for generating higher test frequencies. It also shows the power supply section, including battery input and voltage regulation.
Key components include: MMBD770T1G (Diodes D23, D24, D25, D26), BFR106 (Q21), GALI-74 (MMIC Amplifier U10), LM78L08 (Voltage Regulator U10), 4001SMB (Diodes D27, D28), and various resistors, capacitors, and inductors.
The power supply section details a "10 x AA CELL" battery input and a "M317D" charger circuit. It shows switches (SW8, SW9) for power control and mode selection.