Tektronix 1A5 Instruction Manual page 88

Calibration — Type 1A5
h. Swi t c h the oscilloscope Time/cm to 1 μ s and adjust the
Horizontal Position controls to place the beginning of the
leading edge of the positive square wave at the 2 cm line as
in Fig. 6-26(A).
i. Switch the Type 1A5 VOLTS/CM control to 10 mV.
j. Adjust the Type 1A5 POSITION control to set the right
side of the visible portion of the trace to vertical center of the
graticule as in Fig. 6-26 (B).
k. CHECK — A Input overdrive recovery time. Trace should
return to within 1 cm (10 mV) of graticule center by the time
the trace reaches the 3 cm line as in Fig. 6-26 (B). ( 10 mV
or less within 1 μ s .)
l. Switch the A Input AC-GND-DC control to GND.
m. Wait one minute; using POSITION control, set the trace
to the vertical center of the graticule.
n. CHECK — A Input DC shift due to overdrive. The top
of the waveform should be within 1 cm (10 mV) of the vertical
center of the graticule 1 second after the A Input AC-GND-
DC control is switched to DC. Return the AC-GND-DC switch
to the GND position.
o. Move the 50 Ω termination and cable from the A INPUT
to the B INPUT connector.
p. Us i ng the POSITION control, set trace to vertical center
of graticule.
q. CHECK — B Input shift due to overdrive. Top of wave ­
form should be within 1 cm (10 mV) of vertical center 1
second after the B Input AC-GND-DC control is switched to
DC.
r. Adjust the POSITION control to set the right side of the
visible portion of the trace to graticule vertical center.
s. CHECK — B Input overdrive time. Trace returns to within
1 cm (10 mV) of graticule vertical center by the time the
trace reaches the 3 cm line.
t. Disconnect the equipment from the oscilloscope and the
Type 1A5. Use of the Square Wave Generator has been com ­
pleted. Reset the oscilloscope Triggering Source to Norm and
Horizontal Position controls to midrange.
6-28
Fig. 6-26. ( A ) Preliminary waveform for check of overdrive re ­
covery time, step 22-h. (B)
waveform, steps 22-| and k.
( C) B INPUT overdrive recovery time
waveform, steps 22-r and s.
A INPUT overdrive recovery time