HP 465A- HP 465A Amplifier Impedance Converter 10 Megohms to 50 Ohms 5 Hz to 1 MHz industrialThe HP 465A Amplifier is a general purpose amplifier and impedance converter 10 Megohms to 50 Ohms. The 465A has selectable gain of 20 dB or 40 dB stable over a continuous frequency range of 5 Hz to 1 MHz.