Check Channel Isolation; Check Common-Mode Rejection Ratio - Tektronix 2205 Service Manual

b. Connect the leveled sine-wave generator out­
put via a 5 0 -0 coaxial cable and a 5 0 -0 termination
to the CH 2 V input connector.
OR
c. Set the generator to produce a 50-kHz,
6-division display.
d. Increase the signal
4.2-division display is obtained.
e. CHECK—The frequency
20 MHz.
f. Repeat parts c through e for ail VOLTS/DIV
settings from 10 mV to 5 V, up to the output-voltage
upper limit of the sine-wave generator being used.
g. Move the cable from the CH 2
nector to the CH 1
o r
Vertical MODE switch to CH 1.
h. Repeat parts c through e for all indicated CH 1
VOLTS/DIV switch settings, up to the output-voltage
upper limit of the sine-wave generator being used.

3. Check Channel Isolation

a. Set:
CH 1 VOLTS/DIV
CH 2 VOLTS/DIV
Channel 2 AC-GND-DC
SEC/DIV
b. Set the generator to produce a 20-MHz,
5-division display.
c. Set CH 1 VOLTS/DIV switch to 0.5 V for a
10-division display.
d. Set Vertical MODE switch to CH 2 and ALT.
e. CHECK— The display amplitude is less than 0.1
division.
frequency until
is greater than
Y input con­
or
X input connector. Set the
1 V
0.5 V
GND
0.05 ms
Performance Check Procedure—2205 Service
Move
f. the test-signal cable from the
X
input connector to the
g. Set:
Vertical MODE
Channel 1 AC-GND-DC
a
Channel 2 AC-GND-DC
h. CHECK— The display amplitude is less than 0.1
division.
i. Disconnect the test equipment from the
instrument.
4. Check Common M ode-R ejection Ratio
a. Set:
VOLTS/DIV (both)
Channel 1 AC-GND-DC (both)
Vertical MODE
b. Connect the leveled sine-wave generator out­
put via a 5 0 -0 coaxial cable, a 5 0 -0 termination,
and dual-input coupler to the CHI OR X and CH 2 OR
Y input connectors.
c. Set the generator to produce a 10-MHz,
6-division display.
d. Set Vertical MODE switch to CH 2 INVERT and
ADD.
e. CHECK— Display amplitude is 0.6 division or
less.
f. Disconnect the test equipment from the
instrument.
CH
1
or
CH 2 Y
OR input connector.
CH I
GND
DC
10 mV
DC
BOTH.
NORM,
and ALT
4-5