Schwarzbeck LFPA 9733 Power Amplifier 5Hz - 1MHz

The Schwarzbeck LFPA 9733 is a multi-purpose power amplifier and can be used within the frequency range from 5 Hz to 1 MHz. Typical applications are magnetic immunity testing according to automotive standards and MIL-461E or F.

Hazard warning:
The power cord must be disconnected every time if wires are being connected or disconnected

Attention: During operation dangerous to life high voltages occur at the terminals of the LFPA 9733. If used in an inappropriate way this could lead to a life-threatening situation for the user.

Danger to life!

After the LFPA 9733 is connected to mains it is in standby mode. This is indicated by the orange LED. The CPU supervises the input voltage and the temperature of the amplifier even when in standby mode. To switch the unit on you have to push the “On” button. Along this way the internal modules are activated and checked. After this power on sequence the amplifier is ready for operation.

The display informs about the firmware version, the output voltage, the output current and also the temperature of the transformers/output stage. The signal input is muted when the amplifier has been switched on. This is indicated at the undermost line of the display.

The display informs about the actual peak values of the positive half-wave and the negative half-wave.

Voltage (Up):
Up: positive half-wave / negative half-wave

Current (Ip):
Ip: positive half-wave / negative half-wave

Temperature:
tA+: pos. output stage tA-: neg. output stage
tT1: transformer 1 tT2: transformer 2

By pushing the rotary-encoder (Level / Mute) the signal input can be enabled. You can adjust the output level (256 steps) by rotating the rotaryencoder. The output level is displayed at the undermost line as percentage quotation and stylized as bar chart.

The output voltage of the power amplifier LFPA 9733 is at the maximum when a level of approx. 2.5 Vrms (3.5 Vpeak) is applied to the input and the LEVEL control is set to “100%”. The use of an oscilloscope is recommended to monitor the output voltage.

The load impedance for frequencies lower than 15 Hz must be at least 1.0 Ω. The maximum current must not exceed 20 Arms.

The amplifier is fused with a slow blow 12.5 A fuse at the primary side.

The signal can be tapped from the red wing terminal. The blue wing terminal “COMMON” is connected to the housing electrically.

Even when the amplifier is in standby mode the fans operate at high temperatures.

Please note that the air intake for cooling purposes is located at the side and at the bottom of the amplifier and the warm air is exhausted at the back. The amplifier must not be installed closer than 10 cm to a wall. It has to be installed in a way that the exhausted warm air cannot get into the housing again (thermal short). Pay attention to cooling especially when installing the amp into a 19” rack!

A 19’’-rack mount kit is available optionally.

Interfaces
The amplifier has three external interfaces to communicate with a PC. USB, RS232 and GPIB.

Configuration
You can enter the configuration menu of the interfaces by pushing the rotary-encoder while in standby mode. From here you can chose from three options:

GPIB interface
USB interface
Serial interface

By rotating the rotary encoder the interface can be chosen and will be shown inverse.

Pushing the rotary encoder shows further options of the serial/GPIB interface.

The baud rate of the serial interface can be chosen. The following parameters cannot be changed: 8 data bits, no parity, one stop bit.

The address of the GPIB interface can be set from 1 to 31.

The chosen parameter gets selected by pushing the rotary encoder. The changes will be saved and the amplifier returns into standby mode.