Understanding Power Supplies for Ham Radio

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.