Teledyne LeCroy DA1855A - Manual (Page 23)

Operator’s Manual
922258-00 Rev A 17
50 Ω load. Without the load, the filter's frequency response and transient
response are altered.
1 MHz The 1MHz filter is of the same design as the 20 MHz filter, and the same
remarks apply.
100 kHz The 100kHz filter is an active filter with a 50 Ω output impedance. Transient
and frequency response are independent of the load impedance.
Overload
When a signal, which could damage the DA1855A, has been applied to either input connector, the
DA1855A protects itself by disconnecting the signal. The input coupling mode changes to OFF, and
the OVERLOAD light is turned on.
To reset the amplifier to normal operation, remove the offending input, press any of the input
coupling modes (AC, OFF, or DC). The Overload light will turn off indicating the amplifier is reset.
When the ATTENUATOR is set to ÷1, an input signal of approximately ±19 Volt will activate the
overload protection circuit. Fast transients will draw up to about 70 mA of input current for a brief
period before the input coupling relay acts to disconnect the input.
CAUTION. Inputs in excess of 250 Volt may cause permanent damage to the DA1855A.
The input is not disconnected when the ATTENUATOR is set to ÷10. The input attenuator can
withstand up to 200 Volt continuous input.
Rear Panel
Power
Normal instrument operation is obtained with the power switch in the 1 (ON) position. The
instrument can be used immediately, however it requires a 30 minute warm up period to reach
specified performance. Prior to reaching operating temperature, the amplifier offset will drift and
the output from the Precision Voltage Generator may not be within specification. In high humidity
environments the time to stabilize may be much longer. In high humidity environments or when
warm-up time inhibits power switch left in the 1 (ON) position.
Power Up Indicator
Upon turn-on, the model number and firmware version are briefly displayed in the PVG readout. For
example, 1855.12 indicates that the instrument is a model DA1855A and the firmware version is 1.2.