Fluke 5500A, Service Manual

Page: 198 / 296

5500A
Service Manual
6-72
6-91. Trigger Signal Specifications for the Time Marker Function
Time Marker
Period
Division Ratio [1]
Amplitude into
50
Ω
(p-p)
Typical Rise Time
5 to 50 ms off/1
≥
1 V
≤
2 ns
20 ms to 100 ns off/1/10/100
≥
1 V
≤
2 ns
50 to 10 ns off/10/100
≥
1 V
≤
2 ns
5 to 2 ns off/100
≥
1 V
≤
2 ns
6-92. Trigger Signal Specifications for the Edge Function
Edge Signal
Frequency
Division Ratio
Amplitude into
50
Ω
(p-p)
Typical Rise Time
1 kHz to 1 MHz off/1
≥
1 V
≤
2 ns
6-93. Theory of Operation
The following discussion provides a brief overview of the following SC300 operating
modes: voltage, edge, leveled sine wave, time marker and wave generator. This
discussion will allow you to identify which of the main plug-in boards of the Calibrator
Mainframe are defective. Figure 6-18 shows a block diagram of the SC300 Option, also
referred to as the A50 board. Functions that are not depicted in the figure are generated
from the DDS Assembly (A6 board). For a diagram of all Calibrator Mainframe board
assemblies, refer to Figure 2-1.
6-94. Voltage Mode
All signals for the voltage function are generated from the A6 board and are passed to
the A50 board via the SCOPE_HV signal line. The generated signal (ac or dc) is then
passed from the A50 board to the A90, attenuator assembly, where range attenuation
occurs. The signal is then passed to the SCOPE output BNC on the front panel.
6-95. Edge Mode
The edge clock originates on the A50 board. The signal is then shaped and split to
generate the fast edge and external trigger signals. The edge signal is passed from the
A50 board first to the attenuator assembly (where range attenuation occurs) and then to
the SCOPE connector BNC on the front panel. If turned on, the trigger is connected to
the Trig Out BNC on the front panel.
6-96. Leveled Sine Wave Mode
All of the leveled sine wave signals (from 50 kHz to 350 MHz) are produced on the A50
board. The leveled sine wave signal is passed from the A50 board to the on-board
attenuator assembly. The attenuator assembly provides range attenuation and also
contains a power detector which maintains amplitude flatness across the frequency
range. The signal is then passed to the SCOPE connector BNC on the front panel.
6-97. Time Marker Mode
There are several “ranges” of time marker operation: 5 s to 50 ms, 20 ms to 100 ns, 50 ns
to 20 ns, 10 ns and 5 to 2 ns.