AMT75 Impedance Adapter
4
AMT75 Impedance Adapter Instructions
Oscilloscope Connections
As shown in Figure 2a, the output of the AMT75 adapter connects directly to the
TekProbe II interface on Tektronix TDS Series oscilloscopes. With the addition
of optional accessories, the AMT75 adapter connects to any instrument with a
50
W
BNC or 50
W
SMA input. The shell of the input on all oscilloscopes must
connect to earth ground.
When you connect the adapter to instruments with the TekProbe II interface, the
instrument automatically adjusts the scale factor and sets the oscilloscope input
impedance to 50
W
.
NOTE
. TDS 400 and TDS 400A series oscilloscopes always interpret the
attenuation of the AFTDS adapter as
B
10. The attenuation of the adapter is
actually
B
5. When you use this adapter on these oscilloscopes, divide the
measurement (or scale factor) by 2 to obtain the correct value.
When you connect the adapter to instruments that do not have the TekProbe II
interface, make the settings and calculate the amplitude as follows:
H
Set the oscilloscope input impedance to 50
W
or use an external 50
W
termination.
H
Correct your measurements for the 5X attenuation factor of the AMT75
adapter.
Displayed Amplitude
×
5 = Actual Amplitude
Input Signal Connections
The female BNC input of the AMT75 adapter accepts a male BNC connector.
The signal input cable (source) must be 75
W
. See Figure 2b.
CAUTION.
To avoid damaging the 75
W
input connector, use accessories that are
specifically designed for 75
W
connections. Using 50
W
connectors on the 75
W
input can damage the 75
W
connector and degrade the VSWR of the AMT75
adapter.
Instruments with
TekProbe II
Instruments without
TekProbe II