Check Ac-Coupled Common-Mode Rejection At; Check Ac-Coupled Low-Frequency Response - Tektronix 1A5 Instruction Manual

e. Switch the B Input AC-GND-DC control to DC.
f. Switch the VOLTS/CM control to 10-mV - Retained
Range.
g. CHECK — 1 cm or less vertical display amplitude (2000:1
or greater CMRR).
h. ADJUST — C205D (Fig. 6-21) for minimum vertical dis ­
play amplitude. (1 cm or less for 2000:1 CMRR. Ratios of
50001:1 or more are not uncommon.)
i. Switch the VOLTS/CM control to the 20 V position.
j. Switch the B Input AC-GND-DC control to GND.
k. Set the Oscillator amplitude to its maximum value.
Measure its peak-to-peak value and divide it by 2000. Record
the results.
l. Switch the B input AC-GND-DC control to DC, and the
VOLTS/CM control to .1V - Ret ained Range.
m. CHECK — Vertical display amplitude equal to or less
than that recorded in step k. (C MRR 2000:1 or greater.)
n. ADJUST — C206B (Fig. 6-21) for vertical display amplitude
equal to or less than that recorded in step k. (CMRR 2000:1
or greater. Ratios of 5000:1 or more are not uncommon.)
18. Check AC-Coupled Common-Mode Rejec­
tion at 60 Hz
a. Equipment setup is shown in Fig. 6-20.
b. Set the oscilloscope Time/cm control to 5 ms.
c. Switch the Type 1A5 VOLTS/CM control to 2 V and the
B Input AC-GND-DC control to GND.
d. S e t the Osc i llator for a 60 Hz - 10 V peak-to-peak out ­
put. (5 cm trace deflection . )
e. S w itch the B Input AC-GND-DC control to DC and the
VOLT S/ CM control to 2 mV.
f. CHECK — 2.5 mm or less vertical display amplitude.
g. S i mul t aneously switch the A and B AC-GND-DC controls
to AC.
h. CHECK — Display amplitude 5 cm or less. (1000:1 CMRR).
19. Check AC-Coupled Low Frequency Response
a. E q u i pment s et up is shown in F
b. Switch the Type 1A5 VOLT
A Input AC-GND-DC switch to D
GND-DC s w itch to GND.
c. S e t the osc i l loscope T i m
d. Change the Osc i llator output to 2 Hz, 100 mV peak-to-
peak, providing exactly 5 cm vertical ampli
attenuator in the signal path to reduce the amplitude, if
neces sa ry.
e. Switch the A Input AC-GND-DC s
f. CHECK — 3.5 cm or more display amplitude.
g. Switch the A Input AC-GND-DC switch to GND and the
B Input AC-GND-DC switch to AC.
h. CHECK — 3.5 cm or more display amplitude.
i. Switch the B Input AC-GND-DC switch to GND and
disconnect the flexible T connec
tors. Use of the os ci ilator has been completed.
Calibration — Type 1A5
i g. 6-20.
S/ CM control to 20 mV, the
, and the B Input AC-
c
e/ CM control to .5 s.
t ude. Insert an
w itch to AC.
t or from the INPUT connec ­
6-23