PS20 - 13.8V/20A Linear Power Supply
The PS20 is a robust linear power supply designed for amateur radio operators who demand the cleanest possible power for their equipment. Based on the proven design from Ludens.cl, this kit delivers exceptional performance with minimal noise and ripple.
Key Specifications
- Output Voltage: 13.8V (adjustable over moderate range)
- Continuous Current: Up to 20A
- Current Limiting: Approximately 25A
- Short Circuit Protection: Yes, with adequate heat sink cooling
- Voltage Drop: Extremely low (0.1V for transistors + 0.5V for equalizing resistors)
Innovative Design Features
Unconventional Architecture
The PS20 uses an innovative approach where pass transistors are positioned on the negative rail in common-emitter configuration, rather than the typical emitter-follower arrangement. This design choice delivers exceptionally low voltage drop and improved efficiency.
Superior Heat Dissipation
Since collector connections attach directly to the negative output (typically grounded), no insulation is required between transistors and the cabinet. This significantly improves heat dissipation efficiency and simplifies construction.
Fail-Safe Voltage Adjustment
The voltage adjustment potentiometer is arranged so that if the wiper contact fails, the voltage will decrease rather than increase. This critical safety feature protects your valuable radio equipment from damage due to overvoltage conditions.
Cost-Effective Components
The design uses low-cost 25V filter capacitors rather than expensive 35V alternatives, reducing both cost and physical size without compromising performance.
Power Dissipation
At 20A continuous operation, the power supply dissipates approximately 200W in normal use. During short circuit conditions, pass transistors may reach 130W. A reasonably oversized heatsink is essential for safe operation at rated current levels.
Ideal Applications
- HF and VHF/UHF transceivers requiring clean power
- Sensitive receiver systems
- QRP and homebrew radio projects
- Amateur radio stations where noise-free operation is critical
What's Included
The PS20 kit includes all necessary components, PCB, and comprehensive assembly documentation. Available in both complete disassembled form or partially assembled configurations to suit your building preferences.