5
1017 Technical Manual
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Dimensions & Weight
Dimensions – 290mm x 250mm x 110mm
Weight – 2.4Kg
1.3. Circuit Description
Operating Temperature
0°C to +50°C max. For optimum performance and stability the 1017 should be stored and
used in temperatures between 15°C and 25°C.
The calibrator employs a temperature compensated zener diode as the basic reference
source. This provides the input to an FET chopper amplifier system which operates in a feed
– back stabilised mode, and has a gain value determined by a set of precision wire-wound
resistors which are selected by a 6 decade thumbwheel switch. The output voltage is
variable from 0V to 99.9999V in 6 ranges.
An output resistance of typically 150m
Ω
is maintained on all ranges excluding the 100V
range where the output resistance is 1
Ω
. The maximum output current that can be drawn on
the 10V and 1V ranges is automatically limited to approximately 150mA, or 15mA on the
100mV range. It must be noted that the current on the 10mV range is limited by a 1
Ω
resistance. The output current on the 100V range is 10mA.
The 100V output is generated by driving a step-up transformer with the ’chopped’ D.C.
output from the output of the module. Feedback around the complete amplifier regulates the
output to the set output value.
When the 100mA range is selected, the output current is sensed by a precision resistor.
The voltage generated across this resistor is used to control the output drive voltage, so
regulating the output current.
The resistance range operates by directly switching the thumbwheel switch to the output
terminals.
The deviation control operates by injecting a current into the reference circuitry which either
increases or decreases the reference voltage.
To ensure complete reliability of the thumbwheel switch, double pole gold plated contacts
are used for each position – even if a contact fails, the 1017 will continue to work correctly.
1.4. Power Supply Description
The power supply for this unit is via a Time Electronics PU2 power supply. This unit
provides a battery power supply for portable use, which is automatically charged when
mains operation is used. This is mounted on the rear panel of the 1017. The power supply
is set for 220V – 240V AC mains unless otherwise specified.
When the mains is connected, the charging circuitry provides the correct charge current (40
– 45mA) for the battery and automatically reduces this to at trickle charge (3 – 4mA) when
the battery is fully charged. This means that it is impossible to over-charge the battery.
Approximately 30 – 40 hours use may be obtained between charges, depending on the
output setting.