A microwave power amplifier arrangement for an electron paramagnetic resonance (EPR) system provides amplified microwave pulses having a microwave frequency in the X-band. The arrangement has a microwave input and a microwave output, and comprises at least one transistor amplifier device, and at least one switchable reflection device. A respective transistor amplifier device comprises a transistor amplifier device input directly or indirectly connected to the microwave input (2), at least one transistor, and a transistor amplifier device output directly or indirectly connected to the microwave output. A respective switchable reflection device comprises a PIN diode and a lambda/4 line connected directly or indirectly to the transistor amplifier device output of at least one transistor amplifier device and to a first port of the PIN diode, with lambda being the wavelength of the microwave radiation within the lambda/4 line. A second port of the PIN diode is connected to ground.