Tektronix 11A32 User's Reference Manual page 18

Operating the 11A32 in 11300-series mainframes
AC coupling capacitors are connected differently in the 11A52 and 11A71 than in
the 11A32 and 11A34. Figure 2-1 shows this difference.
Figure 2-1. Location of AC coupling capacitors in plug-in amplifiers.
In the 11A52 and 11A71, the coupling capacitor isolates both the input
termination and the amplifier from external DC voltages. However, the coupling
capacitor in the 11A32 and 11A34 does not.
Always use caution when working with voltages in excess of 25 volts.
When 50 D. Impedance mode is selected and input coupling is set to
AC or DC, a 50 Q termination resistance is connected directly from
the 1IA32 input connector to ground. Take care that the circuit
connected to the 11A32 input will not be damaged by the 50 Q. load.
Switching from 1 MQ. to 50 Q Impedance mode when more than 25
VDC is present at the 11A32 input will exceed the peak input voltage
specification and may damage the 11A32 input relay. A damaged relay
could cause an error in calibration.
2-4
11A32 User Reference Supplement