A bias current of 20 mA may destroy sensitive detectors.
Please pay attention to the correct polarity and careful adjustment of the bias voltage to protect your detector.Put the bias switch to GND (ground) if you do not want to use the internal bias voltage. The positive and the negative supply voltage of the amplifier must be switched “on” and “off” simultaneously in order to avoid overvoltage at the bias output.
The signal at the bias voltage monitor output (pin 7 of the Sub-D control socket) is identical to the detector bias voltage present on the shield of the input BNC socket. By monitoring the signal on pin 7 the desired bias voltage can be adjusted through the bias potentiometer. Even if the bias switch is set to “GND”, the bias voltage can be monitored and set to the desired value.