Yaesu FT-227R Memorizer Block Diagram

Detailed circuit overview of the FT-227R amateur radio transceiver's main, PLL, and control units.

Overall System Architecture

The Yaesu FT-227R Memorizer transceiver's block diagram illustrates the interconnected functional units: the PB-1659 Main Unit, PB-1757 PLL Unit, PB-1555 Tone Squelch (optional), PB-1758/1759 Display/Drive, and PB-1773 PLL Control Unit. This diagram details the signal paths for receive (RX), transmit (TX), audio frequency (AF), intermediate frequency (IF), and phase-locked loop (PLL) control, along with various control and monitoring points.

PB-1659 Main Unit

This unit handles the primary RF, IF, and AF signal processing for both transmit and receive operations.

Receive (RX) Path:

RF Amplifier (Q101: 3SK51): Amplifies incoming RF signals.
Band Pass Filter (BPF): Filters the RF signal.
1st Mixer (Q102: 3SK51): Mixes the RF signal with a 10.7MHz local oscillator signal to produce a 10.7MHz IF.
BPF (XF101): Further filters the 10.7MHz IF.
2nd Mixer (Q103: 3SK40M): Mixes the 10.7MHz IF with a 2nd oscillator (Q104: 2SC372Y) signal to produce a 455kHz IF.
BPF (CF101, CF102): Filters the 455kHz IF.
IF Amplifiers (Q106, Q107, Q108: 2SC372Y; Q109: µPC577H): Amplify the 455kHz IF signal.
Discriminator (D106, D107: IS188FMx2): Demodulates the FM signal.
AF Amplifier (Q113: 2SC372Y): Amplifies the audio frequency signal.
Low Pass Filter (Q114: 2SC372Y L.P.F): Filters the audio signal.
PA Amplifier (Q116: µPC575C2): Power amplifies the audio signal for the speaker.
Speaker (SP): Outputs the received audio.

Transmit (TX) Path:

Microphone (MIC): Input for audio signals.
AF Amplifiers (Q201, Q202, Q203: 2SC372Y): Amplify the microphone audio.
DC Inverter (D201, D202: IS1555x2 IDC): Processes DC signals.
Power Amplifiers (Q204: 2SC535 AMP; Q206: 2SC2053 AMP; Q207: 2SC730 AMP; Q208: MRF212 PA AMP): Amplify the RF signal for transmission.
Low Pass Filter (L.P.F): Filters the transmitted RF signal before the antenna.
Antenna (ANT): Transmits the RF signal.

Control and Auxiliary Functions:

TX 8V Switch (Q214: 2SC372Y SW): Controls 8V for transmit.
Tone Oscillator (Q215: MC14011B TONE OSC): Generates tone signals.
Buffer (Q216: 2SC372Y BUFF): Buffers signals.
Noise Amplifiers (Q110, Q111: 2SC372Y NOISE AMP): Process noise signals for squelch.
Detector (D108, D109: IS188FMx2 DET): Detects signals for squelch.
Switch (Q112: 2SC372Y SW): General purpose switch.
Busy Indicator (Q115: 2SC372Y BUSY): Indicates when the channel is busy.
Meter (METER): Provides signal strength or other readings.
Un-lock B (un lock b): Status indicator.
Relay (RL101 RL): Switches between RX and TX paths.
Regulator (Q117: µPC14308 REG): Provides +13.8V regulated power.
DC Amplifiers (Q209, Q210, Q211, Q212: 2SC372Y DC AMP; Q213: 2SA496(O) DC AMP): Various DC amplification stages.
Switch (Q205: 2SC372Y SW): General purpose switch.
Switch (D206, D207: M1301x2 SW): General purpose switch.
PA Control (Q1: 2SD235(O) PA CONT): Controls the power amplifier.

PB-1757 PLL Unit

This unit is responsible for generating stable frequencies using a Phase-Locked Loop system.

Oscillator (Q401: 2SC372Y OSC): Generates a 10.700MHz signal.
Buffer (Q402: 2SC372Y BUFF): Buffers the oscillator output.
Divider Switch (D302, D303: IS1555x2 D.SW): Divides frequencies.
Buffer (Q304: 3SK40M BUFF): Buffers signals.
Mixer (Q403, Q404: 2SK19GRx2 MIX): Mixes signals.
Amplifier (Q303: 2SC535A AMP): Amplifies signals.
Buffer (Q405: 3SK40M BUFF; Q302: 3SK40M BUFF): Buffers signals.
Voltage Controlled Oscillator (Q301: 2SK19GR VCO): Generates frequencies controlled by voltage.
PLL Mixer (Q305: 2SC535 PLL MIX): Mixes signals within the PLL.
Multiplier (Q311: 2SC710 MULT x 3): Multiplies frequencies by 3.
IF Amplifiers (Q306, Q307: 2SC372Y IF AMP): Amplify intermediate frequencies.
Oscillator (Q310, Q312: 2SC373 OSC): Generates 10.240MHz and 40MHz signals.
Phase Detector (Q309: TC508IP P.DET): Detects phase difference.
Phase Divider (Q308: PD857 P.DIV): Divides phase signals.
Switches (D315~320: IS1555x6 SW): Multiple switches.
Regulator (Q313: 2SC372Y REG): Provides -6V regulated power.
Switches (Q314, Q315: 2SC372Y SW): General purpose switches.
Amplifier (Q316: MPSA13 AMP): Amplifies signals.
Program (IS1555 PROGRAM): Program input.

PB-1555 Tone Squelch (Option)

This optional unit provides tone squelch functionality.

Low Pass Filter (Q501: MC3403d L.P.F): Filters low frequencies.
Buffer (Q503: 2SK19GR BUFF): Buffers signals.
High Pass Filter (Q501: MC3403a HPF): Filters high frequencies.
Notch Filter (Q501: MC3403b NOTCH): Filters specific frequencies.
AF Amplifier (Q505: 2SC372Y AF AMP): Amplifies audio frequencies.
Low Pass Filter (Q501: MC3403c L.P.F): Filters low frequencies.
Decoder (Q502: NE567V DECORD): Decodes tone signals.
Switch (Q504: 2SC372Y SW): General purpose switch.

PB-1758, 1759 Display and Drive Unit

This unit manages the display and associated drive circuitry.

Display (D601~D604: TLR312 x 4 DISPLAY): Four-digit display.
Regulator (Q605: µPC4305 REG): Provides 5V regulated power.
Switch (Q606: 2SC372Y SW): General purpose switch.
Drive (Q601~Q603: MSM561 x 3 DRIVE): Drives the display.
Adder (Q604: MC14008B ADDER): Performs addition operations for display data.

PB-1773 PLL Control Unit

This unit provides control logic for the PLL system and channel selection.

Controller (Q711: MC14081B CONT): Main controller for the PLL.
Switches (Q701~703: MC14519B SW): Multiple switches for control.
Latch (Q704~706: MC14042B LATCH): Latches data.
Up/Down Counter (Q707~709: MC14510B U/D COUNT): Counts up or down.
Up/Down Controller (Q710: MC14049B U/D CONT): Controls up/down counting.
Clock Generator (Q2, Q3: PS4001x2 CK GEN): Generates clock signals.
Channel Switch (CH SW): Selects operating channels.
Manual (MANU): Manual control input.
Memory (MEMO): Memory function input.

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