660 Dual 5-kV Detector Bias Supply
- Two independent bias supplies in a single module for germanium and
silicon detectors
- 0–5 kV or 0–500 V at 0–100 µA
- Remote shutdown feature compatible with ORTEC and TTL outputs from warmup
sensors on germanium detectors
- Reset safety feature on remote shutdown minimizes risk of preamplifier
FET damage
- Selected output polarity indicated before bias voltage is turned on
- Automatic overload protection and overload indicator
The ORTEC Model 660 Dual 5-kV Detector Bias
Supply contains two independently adjustable power supplies for furnishing the bias
voltage to germanium detectors, silicon detectors, or ionization chambers. It can be used
with any detector that draws less than 100 µA of current, and whose gain is insensitive
to the applied voltage. The output voltages are continuously adjustable from zero to full
scale with calibrated and locking 5-turn dials. Each supply provides two outputs
controlled by the same dial: a 0 to 5 kV output, and a 0 to 500 V output. Two 10-segment
bar-graph indicators verify that the selected voltages are being supplied at the outputs.
Security against accidentally changing the
output polarity to the wrong state is ensured by two features. The selected output
polarity for each supply is indicated by front-panel LEDs whenever the NIM bin power is
turned on. Thus, the correct polarity can be verified before the HV ON/OFF switch is used
to turn on the bias voltage to the detector. In addition, the side panel must be removed
in order to alter the output polarity. This discourages unintentional changes.
The Model 660 includes a remote shutdown
feature to protect the preamplifier FET against damage when a cooled germanium or Si(Li)
detector warms up. Each supply includes a BIAS SHUTDOWN input that is compatible with the
standard warmup sensor output on ORTEC preamplifiers. When the preamplifier signals a
warmup condition, the Model 660 shuts off the bias voltage to that detector, and turns on
a SHUTDOWN indicator light. The bias voltage remains off, independent of the signal from
the preamplifier warmup sensor, until the shutdown mode is manually cancelled by pressing
the RESET push button. This protects the preamplifier FET if the detector is cooling down
with the HV ON/OFF switch accidentally left on. For further protection against operator
error in the ORTEC shutdown mode, the bias shut-down input interprets a disconnected cable
or a shorted cable as a warm detector, and responds by turning off the bias voltage. Some
detector manufacturers provide a TTL logic level output from their detector warmup sensor.
A board-mounted jumper in the Model 660 can be moved to the TTL position to make the bias
shutdown input compatible with detectors supplying a TTL output. It is also possible to
disable the bias shutdown feature by moving the board jumper to the BYPASS position. The
Model 660 is shipped from the factory with both supplies set to the ORTEC mode.
The high voltage outputs are protected against
overload. When the bias supply senses an excessive output current demand, it turns on the
overload light and reduces the output voltage until the output current is within tolerable
limits. Recovery from overload is automatic when the excessive current demand is
eliminated.
ORDERING INFORMATION
| Model |
|
Description |
| 660 |
|
5-kV Detector Bias Supply |
| C-24-12 |
|
RG-62A/U 93-Ω Cable with two BNC male plugs; 12-ft length |
| C-36-12 |
|
RG-59A/U 75-Ω Cable with two SHV female plugs; 12-ft length |
|
