Power Supply Basics
Most HF and VHF/UHF base/mobile radios require 13.8V DC power. If your radio doesn't have a built-in power supply, you'll need an external one.
Voltage Requirements
Standard voltage for ham radio equipment is 13.8V DC, which matches a car's electrical system. This allows the same radio to be used mobile and at home.
Most radios tolerate a range (typically 11-16V) but perform best at 13.8V.
Current Requirements
Current (measured in amps) depends on your radio's power output:
| Radio Power | Typical Current Draw | |-------------|---------------------| | 5W (QRP) | 2-3A | | 25W | 5-7A | | 50W | 10-12A | | 100W | 20-23A |
Your power supply should provide at least 20-30% more current than your radio draws at full power.
Example
For a 100W radio that draws 22A at full power:- Minimum power supply: 22A
- Recommended: 25-30A (provides headroom)
Types of Power Supplies
Linear Power Supplies
Traditional design using a transformer.- Pros: Clean power, low RF noise, simple
- Cons: Heavy, large, less efficient, expensive
Switching Power Supplies
Modern design using high-frequency conversion.- Pros: Lightweight, efficient, cheaper, compact
- Cons: Can generate RF noise if poorly designed
Most modern ham radio power supplies are switching supplies with good RF filtering. The noise issue is mostly solved in quality units.
What to Look For
Continuous vs Peak Rating
Make sure the rated current is continuous, not peak. You need sustained current during transmit.Overvoltage/Overcurrent Protection
Good supplies protect your radio from voltage spikes and will shut down if overloaded.RF Filtering
Look for supplies designed for radio use, not generic power supplies.Anderson Powerpole Connectors
Many hams standardize on these. Some supplies include them; otherwise, you can add your own.Adjustable Voltage
Some supplies let you adjust voltage. Useful but not essential.Popular Power Supply Options
Budget ($50-80)
- Generic 30A switching supplies from Amazon
- Work fine but may have some RF noise
Mid-Range ($100-150)
- MFJ-4225MV
- Powerwerx SS-30DV
- TekPower TP30SW
Premium ($150-300)
- Astron SS-30M (switching)
- Astron RS-35M (linear)
- Samlex SEC-1235M
Tips for Power Supply Use
Dedicated Circuit
If possible, use a dedicated electrical circuit for your radio station to avoid interference from other devices.Good Connections
Use appropriate wire gauge and solid connections. Loose connections cause voltage drop and heat.Fusing
Always fuse your power leads close to the power supply. This protects against short circuits.Grounding
Ground your power supply case to your station ground for safety and noise reduction.Ventilation
Power supplies generate heat. Keep them ventilated and don't stack things on top of them.Battery Backup
Consider a battery backup for:
- Emergency communications
- Eliminating power supply noise entirely
- Operating during power outages
A deep-cycle 12V battery with a smart charger works well. You can charge while operating or switch to battery when needed.