Fluke PM3370B Hunting Equipment User Manual


 
HOW TO USE THE INSTRUMENT 4 - 21
VERTICAL MENU 50
The 200 MHz models offer the selection of an input impedance of 50 on all input
channels. The EXTTRIG input has no 50 possibility. The impedance selection
is a subfunction in VERT MENU.
The 50 input impedance is used to obtain a correct impedance to match signal
sources of the same impedance. For interconnection, a coaxial 50 cable must
be used. The 50 position is indicated on the display with the Lz sign (Low Z =
Low Impedance).
- Disconnect all signals from the inputs.
- Using a 50
coaxial cable, connect a 4 Vpp, 2 kHz signal from a
generator with 50
output impedance to channel 1.
- Press the AUTOSET key.
- Press VERT MENU.
- Press the 50
CH1 softkey.
Observe that the displayed signal amplitude changes to half of the original
amplitude. This is caused by the change of the input impedance to 50, which
results in a voltage division between the 50 output of the generator and the 50
input of the oscilloscope.
- Remove the input signal from CH1.
VERTICAL PROBE RANGE INDICATOR
- Connect the probe again.
Since the 10:1 probe delivered with the instrument is a high
impedance probe, the 50 termination is automatically turned off.
At the same time, the sensitivity readout is adjusted automatically
when a 10:1 or 100:1 probe is used. This way you don’t have to
multiply the displayed amplitude by 10 or 100 when you use a Fluke probe with
range indication.
ST5968
9312
CH1
1V
VERT MENU
CH1
1V
L
Z
50CH.
ON
OFF
CHx
detector
ST6021