Operation
The PDA-750 is equipped with an electrically isolated BNC input connector. Current injected into
the center contact (with respect to the outer contact) provides a positive indication on the display.
The equivalent electrical circuit of the unit as is illustrated below.
1 . 2 3 4 5
Input
Output
Bias
Range
Equivalent Circuit
Display
Current input to the unit generates a voltage across the range feedback resistor. This voltage is then
measured and displayed in units of amperes. A variable bias voltage may be introduced in series
with the detector in use. The output presented is calibrated such that 2.0000V represents the full
scale range in use, e.g. 2.0000 V corresponds to 20.000 nA and so on.
-3-
Control Function
Power
Offset
Range Set
Amps/Watt Set
Bias Set
Bias Engage
Amps/Watt Engage
Set
Alternately applies and removes power to the unit.
Offsets the reading by up to +/- 20 000 counts.
Selects one of seven ranges in conjunction with rotary Set control. Units
LEDs and decimal points indicate the range that is currently in use.
Momentary push button used in conjunction.with rotary Set control.
Inputs an A/W cal factor that is displayed while button is pushed.
Momentary push button used in conjunction.with rotary Set control.
Selects a level of bias voltage that is displayed while the button is
pushed. Pushing in on rotary control accelerates the setting.
Alternately enables/disables the A/W setting. When engaged, all subse-
quent current readings are divided by the A/W cal factor. LEDs will then
indicate units of Watts.
Alternately adds or removes the selected bias voltage in series with the
input.
Changes the value of the variable selected by the Set button in use.
For the remainder of this discussion refer to the front panel display and controls drawing that appears on the
following page.
Содержание PDA-750
Страница 6: ...4 PDA 750 Front Panel Controls...
