Yaesu FP-757HD Heavy Duty Power Supply
For the FT-757GX HF Transceiver (also compatible with FT-180, FT-180A, FT-77, FT-707)
Product Description
The Yaesu FP-757HD is a robust external AC power supply and speaker unit designed to provide a stable 13.5 VDC output at up to 20 amperes for extended periods. It is specifically intended for use with the FT-757GX HF transceiver and other similar radio equipment. The unit features excellent voltage regulation and a conservative design, ensuring reliable and long-lasting operation even under heavy duty cycles, such as continuous AM, FM, or RTTY transmissions. A built-in, thermally-controlled cooling fan automatically activates during high-current demand periods to maintain optimal operating temperature and prevent overheating.
Specifications
| Parameter | Value |
|---|---|
| Output Voltage | 13.5 VDC |
| Output Current | 20 Amperes (Extended Duty Cycle: 30 minutes ON / 30 minutes OFF) |
| Ambient Temperature Range | 0°C to +40°C |
| Input Voltage Options | 100/110/117/200/220/234 VAC, 50/60 Hz |
| Case Dimensions (H x W x D) | 93 mm x 240 mm x 235 mm |
| Weight | Approx. 6.9 kg |
| Speaker Output Power | 3 Watts at 4 Ohms |
Installation and Operation
Important Safety Warning: Please note that the manufacturer's warranty does not cover damage resulting from improper supply voltage selection or the use of an incorrect fuse. Always verify that the voltage setting on the rear panel of the FP-757HD matches your local AC mains supply voltage before connecting the unit to power.
Voltage Selection and Fusing:
The FP-757HD is designed for global use with multiple input voltage settings. Ensure the correct setting is selected on the rear panel. The primary winding of the power transformer must be connected according to the voltage requirements of your region to prevent damage.
- For 100/110/117 VAC input: Use a 6-ampere fuse [fuse symbol].
- For 200/220/234 VAC input: Use a 3-ampere fuse [fuse symbol].
Connection Steps:
- Before connecting, confirm all voltage and fuse settings are correct.
- Connect the DC output cable from the FP-757HD to the 'DC 13.5V' jack on the rear panel of your transceiver.
- Optionally, connect an external speaker to the 'EXT SP' jack on the transceiver. This connection will automatically mute the transceiver's internal speaker.
- On the rear of the FP-757HD, ensure the cooling fan's lead is connected to the 'FAN' jack. This enables thermal control of the fan.
- Turn the FP-757HD power switch ON. It is crucial to power ON the FP-757HD before powering ON the transceiver.
Operating Guidelines:
- To prevent overheating and ensure longevity, avoid transmitting at full power continuously for more than 30 minutes. For longer transmissions, reduce the output power by 50%.
- If the cooling fan is running, do not switch the FP-757HD OFF immediately. Wait until the fan stops spinning, which indicates that the internal temperature has returned to a safe, normal level.
Diagram Descriptions
Front and Rear Panel Layouts
FP-757HD Front Panel: The front panel features a speaker grille, a power ON/OFF switch, and connection terminals labeled 'DC 13.5 V' [plus symbol]/[minus symbol] and 'EXT SP' [speaker symbol].
FP-757HD Rear Panel: The rear panel includes a selector for AC input voltage (100/110/117/200/220/234 VAC), the DC 13.5V output connector, the external speaker jack, and the cooling fan connection.
Transceiver Front Panel (Example: FT-757GX/SX): A visual reference shows the typical front panel layout of a compatible transceiver, including its controls and display.
Connection Diagram (Page 1): An illustration depicts the physical connections. It shows the FP-757HD with its 'DC 13.5 V' output and 'EXT SP' terminals. The AC power input is shown as 'AC 100 V'. The FT-757GX/SX front panel is shown with corresponding 'DC 13.5 V' and 'EXT SP' jacks.
Internal Circuit Diagram (Page 2)
The detailed circuit diagram outlines the internal electronic architecture of the FP-757HD. It comprises several key functional blocks:
- AC Input and Power Transformer: The diagram shows the primary side connections for selectable AC input voltages (100V, 110V, 117V, 200V, 220V, 234V) feeding into the main power transformer (T1). An input fuse (F1, rated 6A) is present for protection.
- Rectification and Filtering: A bridge rectifier configuration using diodes (D101-D105) converts the AC voltage from the transformer to pulsating DC. Smoothing capacitors (C3, C4, C5) filter this DC voltage.
- Voltage Regulation Circuit (AVR UNIT PB-2156): This section utilizes transistors (Q1-Q3, Q101-Q103), resistors (R101-R104), and capacitors (C101-C104) to create a stable, regulated 13.5 VDC output. A thermal switch (TSI) is integrated to monitor temperature.
- DC Output Stage: The stabilized 13.5 VDC is made available through the output connector (P1).
- External Speaker Amplifier: A dedicated amplifier (SPI) drives the external speaker connected via the 'EXT SP' jack (P2).
- Cooling Fan Control: The circuit includes provisions for the cooling fan (JOI, P3), which is activated based on signals from the thermal switch (TSI).
Component Identification: Standard electronic component designators are used throughout the diagram, such as 'R' for resistors, 'C' for capacitors, 'D' for diodes, 'Q' for transistors, 'RL' for relays, 'F' for fuses, 'P' for connectors, 'J' for jacks, 'VR' for variable resistors, and 'T' for transformers.
