RM KL503HD – (300W 12V) AM-FM-SSB Linear Amplifier


Introducing the RM KL503HD, a powerful 12V linear amplifier designed for AM, FM, and SSB modes.


Operating effectively in the 25-30 MHz frequency range, this amplifier is versatile and robust, ideal for various communication needs. With a drive power ranging from 1 to 35W, the KL503HD ensures optimal performance across all modes.

The RM KL503HD is equipped with a six-position power selector, allowing users to fine-tune their output power easily. This feature is controlled via a user-friendly knob located on the front panel, making adjustments both quick and convenient. Additionally, the amplifier boasts an RX preamplifier with electronic switching. This preamp can be activated with a simple flip of a switch on the front panel, enhancing receiver performance significantly.

Designed with efficiency and reliability in mind, the KL503HD provides up to 300 watts of output power, ensuring clear and strong signal amplification. This model is an excellent choice for enthusiasts and professionals alike, offering high-quality amplification in a compact and durable package.

Whether for professional communication, amateur radio activities, or other applications within its specified frequency range, the RM KL503HD delivers exceptional performance and versatility, making it a valuable addition to any setup.


Operation Frequency25 – 30 MHz (10 m Amateur HF Band)
Modulation TypesSSB, CW, AM, FM, data etc (All narrowband modes)
Transistor8 x RM3 Mosfet + 1x RM4 Mosfet Driver
Max I/P Current30A
Power Supply13V DC ± 1V 40A
Input Fuse (Internal)3 x 10A (5 x 20 mm Fast)
Input RF Power1 – 35 Watt max (All modes)
Output RF Power300 Watt max
Maximum Bypass Power (Amplifier off)50 Watt max
Input VSWR1.1 – 1.5:1
Output VSWR Maximum2.5:1
Harmonic Output> -50 dBc, 25 – 30 MHz
Dimensions170 x 295 x 62 mm
Weight2 kg

Additional information

Weight2.3 kg