HP 400E

The 400E AC Voltmeter is primarily intended as a voltmeter, however it can indicate both voltage and dB. The meter has a linear AC scale with a logarithmic dB scale underneath. The voltage range is 1 mV to 300 V full scale. The dB range is -72 dBm to +52 dBm. Meter calibration responds to the absolute average value of the applied signal, calibrated in RMS volts from 10Hz to 10MHz. The accuracy as a % of reading is: ?4% (10 to 20Hz), ?2% (20 to 40Hz), ?1% (40Hz to 2MHz), ?2% (2 to 4MHz), ?4% (4 to 10MHz). Input impedance is 10 Mohms. The AC amplifier output is 150 mV rms open circuit for full scale meter indication.