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3.1. GENERAL
The 428 contains an internal power supply that must
be used in conjunction with a Nuclear-Standard Bin
and Power Supply such as the ORTEC 4001/4002.
The 428 is intended for rack mounting; therefore if
vacuum tube equipment is operated in the same
rack, there must be sufficient cooling air circulating
to prevent any localized heating of the all-transistor
circuitry used
throughout
temperature of equipment mounted in racks can
easily exceed the recommended maximum unless
this precaution is taken. The 428 should not be
subjected to temperatures in excess of 120 F
(50 C).
3.2. CONNECTION TO POWER
Turn off power when inserting or removing modules.
The ORTEC 4000 Series is designed so that it is not
possible to overload the Bin Power Supply with a full
complement of modules in the Bin; since, however,
this may not be true when the Bin contains modules
other than those of ORTEC design, the Power
Supply voltages should be checked after the
modules are inserted. The ORTEC 4001/4002 has
test points on the Power Supply control panel to
monitor the dc voltages.
4.1. INITIAL TESTING
Refer to Section 5.1 of this manual for information
concerning testing performance.
4.2. POLARITY SELECTION
The Polarity Switch is located on the front panel and
also serves as an On-Off switch for power to the
428. When changing the polarity of the output bias
voltage, stop the switch in the Off position for a few
seconds before switching to the other polarity. This
pause in the Off position is necessary to allow the ac
starting circuit for the dc to dc converter to recharge.
3. INSTALLATION
the
module.
The
4. OPERATING INSTRUCTIONS
2
3.3. CONNECTIONS TO THE 428
The ORTEC 428 is compatible with ORTEC
detectors and with preamplifiers that have provisions
to accept bias voltage for the detector. All operating
controls and bias voltage output connectors are
located on the front panel. The output connectors
are the type SHV and are not compatible with
ordinary BNC connectors. A perforated shield
encloses the unit so that high voltages are not
exposed.
Do not operate this unit without the
protective covers, since lethal voltages are
exposed inside the instrument.
Tip jacks are provided for monitoring the current in
each detector. See Section 4.5 for information on
appropriate dc meters. Always have power for the
428 turned off before connecting or removing meter
leads. Any meter used as a current monitor is
connected in shunt with 1 MÙ on the output circuit
and reduces the output impedance.
4.3. BIAS VOLTAGE INDICATOR LIGHT
The Bias Voltage indicator light is a neon light
located between the two front panel SHV output
connectors and indicates that the power is turned
on. If the 428 is turned on and the Bias Voltage
indicator light does not illuminate, turn the Polarity
Selection switch to the Off position for approximately
2 sec and then return it to the desired polarity. This
pause in the Off position is necessary to allow the ac
starting circuit for the dc to dc converter to recharge.
WARNING
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