Specifications

Operating Manual SEFRAM 4451
M4451 A00
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output, parameter or mode displayed selected.
3.3 Front Panel Controls
The front-panel controls select, display, and change parameter, function, and mode settings.
Use the rotary input knob and the cursor movement keys to enter data into the pulse generator.
To change a setting:
1. Press the key that leads to a required item.
2. Move cursor using cursor keys to the appropriate position in the numeric field.
3. Use the rotary input or the numerical keyboard to change the value of the displayed item. Changes take
effect immediately.
The following subsections describe the function of each front panel key and connector.
3.4 Connectors
The function generator has two BNC connectors on the front panel and one on the rear panel where you can
connect coaxial cables. These coaxial cables serve as carrier lines for input and output signals delivered to
and from the function generator. Additionally, for ATE 19" rack systems, on the rear panel are two
connectors for optional wiring of the front connectors to the rear panel.
Output Connector
Use this connector to transfer the main output signal from the function generator.
Trig In Connector
Use this connector to apply an external trigger or gate signal, depending on the pulse generator setting, to the
generator.
Sync Out Connector
Use this connector to output a positive TTL sync pulse generated at each pulse cycle.
3.5 Output Connections
The pulse generator output circuits operate as a 50 ohms voltage source working into a 50 ohms load. At
higher frequencies, un-terminated or improperly terminated output cause aberrations on the output waveform.
In addition, loads less than 50 ohms reduce the waveform amplitude, while loads more than 50 ohms increase
waveform amplitude.
Excessive distortion or aberrations caused by improper termination are less noticeable at lower frequencies.
To ensure pulse integrity, follow these precautions:
1. Use good quality 50 ohms coaxial cable and connectors.
2. Make all connections tight and as short as possible.
3. Use good quality attenuators if it is necessary to reduce pulse amplitudes applied to sensitive circuits.
4. Use termination or impedance-matching devices to avoid reflections.
5. Ensure that attenuators and terminations have adequate power handling capabilities.
If there is a DC voltage across the output load, use a coupling capacitor in series with the load. The time
constant of the coupling capacitor and load must be long enough to maintain pulse flatness.
Impedance Matching
If the pulse generator is driving a high impedance, such as the 1 Mohm input impedance (paralleled by a
stated capacitance) of an oscilloscope vertical input, connect the transmission line to a 50 ohms attenuator,
a 50 ohms termination and to the oscilloscope input. The attenuator isolates the input capacitance of the
device and terminates the pulse generator properly.