Fluke PM3082 Service Manual page 419

UNIT DESCRIPTIONS
Introduction toexternal trigger option
The External Trigger Input option provides an extra input at the rear of the oscilloscope. This input
can be used as the trigger source for the Main Time Base (MTB). The option is factory-installable only.
The external trigger requires a small printed circuit board, a rear panel BNC socket and a coaxial
interconnection cable.
The small printed circuit board is equipped with soldering pins that fit directly into unit A1. Refer to
figure 1 for the exact location. The lay-out of this unit is given in figure 4; the belonging circuit diagram
in figure 5.
The EXT TRIG input is suitable for use with the supplied 10:1 probe. The input characteristics are
similar to those of CH1 ...CH4.
If External is chosen as trigger source, then the following trigger functions remain available:
- trigger filters ac, dc, lf_rej and hf_rej
- level-pp function
- +/- slope selection
- noise on/off
If External trigger is chosen as trigger source, then TV trigger mode is not available.
Line (50/60 Hz mains) as trigger source is not available.
If the External trigger option is present together with 'Y- out' option, then the DTB gate output of the
Y-out is not available.
A diode V7801 (BAV99, 5322 130 34337) is added on signal unit A1. This diode is connected to the
'panel version identification' circuit D9013. By means of this, the internal software knows that the
external trigger option is present. Diode V7801 is located on unit A1 between V7802 and R7077.
Characteristics
The following has to added to chapter 2.3.1 of 'characteristics'.
CHARACTERISTICS
Source
SOURCE(S)
MTB- triggering
Input characteristics
INPUT CONNECTOR
INPUT IMPEDANCE
R parade
- value
- tolerance
C parallel
- value
- tolerance
DYNAMIC RANGE
Up to 10 MHz
SPECIFICATION
CH1 ... CH4
External
Composite
BNC
1 MQ
±1 %
25 pF
±5 pF
±2.5 V
ADDITIONAL INFORMATION
No line triggering
At rear of instrument
Measured at freq.dM Hz
Symmetrical
5.11-7