The HP 3437A is a High Speed 3 1/2 digit HPIB Systems Voltmeter with sample and hold. It measures DC volts with input ranges of 0.1, 1, and 10 volts full scale. The sample and hold allows for it to be used as an instantaneous voltmeter. The trigger delay can be set from 0.1 microiseconds to 1.0 second and the number of readings can be set from 0 to 9999. The 3437A is HP-IB programmable and has two data output modes: serial ASCII out put and Packed output. The maximum reading rate varies from 3600 to 5700 readings per second depending on the data mode. The input of this unit is what appears to be a 3-pronged BNC connector, this is shown in the photo.
 

• High Speed 3.5 digit system voltmeter with sample and hold
• Measures dc volts, provides trigger delay, has burst reading capability, HP interface bus (HP-1B)
• Has 3 dc floating input ranges: 0.1V, 1.0V, 10.0V full scale with a maximum display of '1998'. Sample and Hold allow the 3437A to be an instantaneous reading voltmeter. The trigger delay can be set from 0.1us to 1.0 second and the number of readings can be set from 0 to 9999 readings.
• Size: 3.5" H x 8.375" W x 20.75" D
• Weight: 12 lb 4 oz