The HE641B from Sainty-Tech Communications Limited is a RF Amplifier with Frequency 1000 to 3500 MHz, Gain 24 to 25 dB, Gain Flatness ±1.5 dB, Noise Figure 5.5 dB, Output Power 23 to 23.5 dBm. Tags: Power Amplifier. More details for HE641B can be seen below.