Comparison Between Switching DC Power Supplies and Linear DC Power Supplies
There are two mainstream circuit architectures for DC voltage regulation. The first is the traditional linear power supply, which relies on a transformer as the core step-down component paired with voltage stabilizing circuits. The second is the widely adopted switching power supply composed of electronic circuits operating in switching mode. Both types have their respective advantages and disadvantages.
Linear Power Supplies
Advantages: Output ripple is easy to suppress; the circuit structure is simple and convenient for maintenance.
Disadvantages: Bulky in size; transformers and large-capacity capacitors are mandatory; low energy conversion efficiency.
Switching Power Supplies
Advantages: Compact size, light weight, relatively high conversion efficiency, and no need for costly large transformers or bulky capacitors.
Disadvantages: Relatively complex circuit structure leading to difficult maintenance; inherent switching frequency electromagnetic interference; output ripple is harder to control.
With the maturity of switching power supply technology and continuous price hikes of copper metal (transformer manufacturing consumes massive copper wire), the cost advantage of traditional linear power supplies has gradually faded, while switching power supplies for high-current output show increasingly prominent price merits. Nowadays, compact external power adapters for digital and electronic products are progressively replaced by lightweight switching power supplies.
For amateur radio operators, apart from stable low-voltage DC output, power supplies must maintain extremely low ripple and high-frequency interference to avoid substantial disruption to shortwave radio signal reception. Traditional transformer-based linear power supplies perfectly meet such requirements, which is why many veteran HAMs recommend linear power supplies.
Nevertheless, modern communication-grade switching power supplies can effectively suppress interference via filtering, shielding and other technical means to comply with communication power supply standards. Many original and built-in power supplies of broadcast stations adopt switching power supplies, meaning communication-specific switching power supplies are fully applicable to shortwave communication. Practical experience proves that VHF/UHF walkie-talkies have loose power supply requirements; modified second-hand computer switching power supplies can stably power vehicle-mounted radios.
In addition, switching power supplies are equipped with sophisticated protection circuits, including overvoltage protection, overcurrent protection and internal fault detection. The unit will cut off output once an internal failure occurs to prevent damage to connected electrical equipment. Without dedicated auxiliary circuits, the regulating tube of an ordinary linear regulated power supply may break down and short-circuit, resulting in dangerous high-voltage output. Many HAMs have suffered equipment damage caused by abnormal voltage surges from failed power tubes inside linear power supplies.
It is easy to distinguish switching power supplies from linear power supplies. Aside from product specifications, users can check whether a large transformer is installed inside the unit. Linear power supplies feature a large, heavy main transformer that occupies most of the internal space, whereas transformers used in switching power supplies are far smaller. At the same power output rating, switching power supplies weigh much less than linear power supplies.