Fluke 5820A, Руководство по обслуживанию

Страница: 37 / 158

Theory of Operation
Introduction
2
2-9
2-11. Current Module
For the A81 Current Board, A55 supplies the reference signal. This signal is inverted
with respect to polarity of the output current (a negative voltage results in a positive
current output). A81 has three ranges: 100 µA to 1.0999 mA, 1.1 mA to 10.999 mA and
11 mA to 100 mA. The board limits the compliance to 2 V.
2-12. Overload Mode
The source voltage for the overload mode is generated on the A51 Voltage/Video Board.
The voltage is applied to the external 50
Ω
load, and the circuit current is monitored by
A6.
2-13. Trigger
The A55 marker clock signal is used to generate the trigger signals. There are two trigger
output SMB connectors on A55. The right angle SMB should be used to route the trigger
signal to the front panel. The vertical connector should be used to route the trigger signal
to the optional GHz module, if installed.
2-14. High Frequency Switching
For the standard single channel calibrator, output signals, except for current and trigger,
are routed to a high frequency switch. From the switch, the signals are cabled to the
5820A-4096 output block. For the single channel unit, the trigger signal and current
signal are cabled directly to the output block and current loop, respectively. A high
frequency relay is used to select between the auxiliary input signal, Auxin, and the
output signal. The selected signal is cabled to connectors on the front panel. In five
channel units, additional high frequency switches are used to route the trigger signal out
channel 1 or channel 5.
2-15. 5 Channel Option
This option multiplexes the output to one of the 5 channels. All signals, except for
current, are routed through this switch system.
2-16. GHz Option Module
The GHz option extends leveled sine from 600 MHz to 2.1 GHz and adds a 150 ps, 250
mV fast edge signal. For more information on the GHz Option Module, see the Options
Chapter.