AC signal superimposed with DC bias_Safety instructions for using signal generator

A signal generator is a device that can provide electrical signals of various frequencies, waveforms, and output levels. It is used as a test signal source or excitation source when measuring the amplitude characteristics, frequency characteristics, transmission characteristics, and other electrical parameters of various telecommunication systems or telecommunication equipment, as well as when measuring the characteristics and parameters of components. Signal generators, also known as signal sources or oscillators, are widely used in production practice and the field of science and technology.

The use of signal generators is already very common, so various faults are inevitable during use.

Common faults of signal generator are as follows:

1. Power failure: Cannot boot normally

2. Output fault: abnormal impedance; no signal; abnormal signal amplitude

3. Display failure: flower screen; black screen

4. Button failure: the button does not respond; the adjustment knob does not respond

5. Interface failure: storage medium is not recognized; cannot connect to the control system

6. Other usage issues, etc.

So how to avoid the above faults of signal generator? Below, Xi'an Antai Instrument Repair Center Network shares the precautions for using signal source:

1. Electrostatic protection

Static electricity can generate a voltage of tens of thousands of volts in an instant, which can cause fatal damage to electronic components. Attenuators and mixers in signal sources are extremely sensitive to it and are particularly easy to be damaged. Therefore, when using signals, attention should be paid to static electricity protection. It is worth mentioning that some static electricity cannot be sensed by the human body, but it is enough to cause damage to the instrument.

1. Please use the standard 3-core AC power cord that comes with the signal source;

2. Static electricity can damage the instrument and harm the user. Proper grounding can avoid the accumulation of static electricity;

3. In the absence of protective grounding, please do not damage the grounding of wires, power cords or transformers;

4. Check the quality and polarity of the AC power supply. Generally, the voltage used by the instrument is 100V, 120V, 220V, with an error of +/-10%, or 240V, with an error of +5%/-10%. The grounding resistance should be less than 1 ohm. The voltage difference between the neutral wire and the ground wire is less than 1 volt. Please install an uninterruptible power supply if necessary.

5. Instrument operators should wear anti-static clothing, anti-static shoes, and anti-static wristbands. And test whether the anti-static preparation is good before using the instrument each time.

2. The output power of the signal generator should not be too large

1. Avoid front-end damage caused by the output level setting of the signal source. Reflection of the output signal or external bias may cause front-end overload and damage the front-end components. The typical reverse power protection level is 33dBm (2watt);

2. Turn on the connected instrument or turn on or off the device under test after reducing the signal amplitude to a minimum safe level to avoid accidental impact of the signal on the input and output ports of the signal source;

3. Avoid testing to allow DC or RF signals to be input to the RF output – avoid front-end damage caused by the signal source output level setting. Reflection of the output signal or external bias may cause front-end overload and damage the front-end components. The typical reverse power protection level is 33dBm (2watt);

4. Turn on the connected instrument or turn on or off the device under test after reducing the signal amplitude to a smaller safe level to avoid unexpected impact of the signal on the input and output ports of the signal source;

5. Avoid testing systems that allow DC or RF signals to be input into the RF output and IQ output ports; use DC blocks, limiters, and external attenuators appropriately when necessary.

Frequent overload output signals have adverse effects on the signal source and will reduce the service life of the signal source. Agilent signal sources have different output powers in different models and with different options. Therefore, when using a signal source, you should read the Data Sheet of this model of signal source carefully. Use the instrument within the power output range given in the Data Sheet.

3. When testing active devices such as amplifiers, the output end of the signal source must be protected against reverse power, and do not press the output key when the RF cable is not tightened.

1. Pay attention to impedance matching. If the impedance matching is not good, the reflected signal caused by it will directly enter the reverse protection circuit inside the signal source, causing an impact on the reverse protection circuit. The more frequent the impact, the faster the aging of the reverse protection circuit. Correctly setting the output power value and good impedance matching can delay the aging of the device and reduce the failure rate.

2. When testing a high-power repeater, there will be high reverse power, and a power attenuator must be added at the output end of the signal source.

4. If the initial measurement of the device will produce DC bias, a DC block must be added to the output end of the measurement signal source.

When the DC bias enters the output end of the signal source, it will affect the reverse power protection circuit of the signal source and reduce its service life.

5. Mechanical stress

Do not place heavy objects (such as high-power attenuators, etc.) at the output end of the signal source. 6. Maintain a good operating environment

Good grounding, ventilation and heat dissipation are necessary to extend the service life of the signal source.

1. The electrical environment for Agilent instruments must meet Agilent's power supply quality requirements, which are similar to the Class A standard for national computer rooms.

2. Clean the air outlet of the signal source regularly to ensure that there is no dust blocking the heat dissipation of the instrument. Poor ventilation will cause overheating and damage to the instrument. The recommended operating temperature is 20-30°C, and the ambient temperature must be <35°C;

3. When the signal source is not in use, please turn off the RF output.

4. When the instrument is installed in a cabinet, ensure that the convection inside and outside the instrument is normal. The ambient temperature must be lower than the product operating temperature, which is 4°C for every 100 watts consumed. If the cabinet consumes more than 800 watts, forced convection cooling must be used.

7. Correctly carry the instrument

1. Use the handle to lift the instrument during transportation;

2. Avoid lifting the instrument by placing your hands on the front panel. If they slip, the keyboard, knobs and connectors may be damaged;

3. For heavier instruments, please use a cart or have two people carry them.

4. Use appropriate packaging during transportation.

Using unprofessional packaging materials may cause damage to the instrument. Do not use styrene balls as packaging materials. They will not adequately protect the instrument and will generate static electricity that may damage the instrument. If possible, please keep the original packaging for reuse.