RM KL 503 is an all-mode 20-30MHz 300W amplifier, The 250-watt solid-state mobile amplifier operates between 20-30MHz, offering a 6-way output power control and a low-noise pre-amplifier. Safety features include an electronic switch and inversion polarity protection. It requires 12-14 Vcc supply voltage and 12-30A input energy/power, with input power ranging from 1-6W and 2-12W for SSB. The maximum output power is 250W, reaching 450W PEP for SSB.

This versatile amplifier supports AM, FM, SSB, and CW modes, safeguarded by a 3 x 10A fuse. It has compact dimensions of 170 x 295 x 62mm, weighs 1.5 Kg, and features an antenna preamplifier with a 26 dB gain.

In conclusion, this amplifier is a reliable and efficient choice for various modes of operation, offering a wide range of features in a compact and lightweight design. The safety measures, along with the 6-way output power control and antenna preamplifier, make it a valuable addition to any mobile communication setup.