BNC PB-4 / PB4 Precision Pulse Generator

Features

• Flat Top or Tail Pulse
• Repetition Rate 250 kHz
• Rise and Fall Times Independently Adjustable
• Output Impedance 50 ohms
• Temperature Coefficient +/-5 ppm/oC
• Integral Linearity +/-50 ppm
• Amplitude shift less than 0.03% at 50% duty
• factor

Description
The Model PB-4 provides either a tail or flat top pulse with an integral linearity of +/-50 ppm and an amplitude temperature coefficient of +/-5 ppm/oC. The Model PB-4 is designed to test stability, linearity, and resolution of nuclear instruments employed in high resolution spectroscopy. It also offers the high count rates that are so important in many of these tests.

Applications

• Use as a reference peak for spectrum stabilization.
• Testing count rate effects up to 250 kHz
• Measuring differential and integral linearity of pulse height analyzers
• Measuring noise from preamplifiers and amplifiers

Description
The Model PB-4 employs a solid state chopper (no mercury relays) which samples either an internal DC reference voltage or an externally supplied reference source. The output of the chopper is connected to a high gain, fast slewrate operational amplifier to provide the possibility of driving heavy loads. The internal DC reference source, the chopper and the operational internal DC reference voltage or an externally supplied reference source. The output of the chopper is connected to a high gain, fast slewrate operational amplifier to provide the possibility of driving heavy loads. The internal DC reference source, the chopper and the operational amplifier are all enclosed in a proportional control oven whose internal temperature changes only 0.01oC for a 1oC change in ambient.

Sliding Pulse Operation
A sliding pulse generator provides a pulse train of linearly increasing (or decreasing) pulses to test the differential linearity of multi-channel pulse height analyzers. To obtain a sliding pulse train from the Model PB-4 it is necessary to connect a Berkeley Nucleonics Model LG-1 Ramp Generator to its External Reference input. The solid-state chopper in the Model PB-4 samples the ramp at periodic intervals. The output of the Model PB-4 is then connected to the pulse height analyzer. If the analog-digital converter is linear and the magnetic core storage is functioning correctly, an equal number of counts will be stored in each channel and the display will be a horizontal straight line. However, if the analyzer is non-linear the display may curve up. If the magnetic core storage is defective there may be a notch in the display. The differential linearity of the sliding pulse train is better than +0.1%. The above approach is the fastest, most accurate way of testing a pulse height analyzer.