Model PB-5
Why is the PB-5 flat top pulse not symmetrical for minimum settings (rise time 50 ns fall time 500 ns)? Symmetry would require a fast discharge of capacitors used to produce exponential tails. The critical issue in the PB-5 is to preserve exponential decay with a clean return to the baseline. The PB-5 meets the same fall time specification as the PB-4 with a cleaner signal as it decays to the baseline - allowing twice the rep rate (500 kHz) as the PB-4. (Back)
How do I set up the pulser for the best MCA linearity measurement? Best results are accomplished by multiple sweeps at the shortest ramp time (90 seconds). Set the number of sweeps to 999, giving a run time of just over 24 hours. For unusually demanding needs, the measurement can be repeated for several days. Since any temperature corrections are made between sweeps (not during the ramp), ramp times of 15 minutes may not give the required accuracy. Short ramps allow good random statistics for all channels as long as many sweeps are made. (Back)
Is the "clamped mode" a baseline restorer for high rate applications? No, the clamp simply preserves the amplitude of the pulse when the tail time is long compared to the desired rep rate. This feature is accomplished by clamping the pulse to the baseline before the exponential decay is completed thus allowing the next pulse to start from the baseline rather than some point on the tail. It is recommended that the delay time be set to 3 or 4 us to allow a full recovery to the base line. (Back)
Can the PB-5 be operated remotely from a PC? Yes, a RS-232 port is available for this feature. Put the PB-5 in "remote" using the main menu. If the manual or PC commands are not available, type "help" and all commands will be listed. (Back)
How do I set up HyperTerminal when using the remote operation? Use the following settings for HyperTerminal - Baud rate: 9600, Data bits: 8, Parity: None, Stop bits: 1, Flow control: None, Emulation: VT 100 (Back)
Is there a way to sweep through a known energy region or put the pulser in a particular energy channel? Yes, the main menu allows the pulser to be calibrated in keV. This feature is convenient when peaks or regions of interest are known in keV. (Back)
What is the minimum amplitude adjustment (resolution) of the PB-5? 155 uV adjustments can be made on the key pad or spinner knob. Each "click" of the spinner makes this minimum adjustment. (Turning the spinner fast will allow it to slew millivolts or volts.) (Back)
