Tektronix TYPE L Instruction Manual page 9

Beam Indicator neons
is approximately centered.
6. Rotate the INTENSITY
until the free-running trace appears on the
crt. Center the trace with the vertical and
horizontal positioning controls.
7. Adjust the FOCUS,
INTENSITY controls to obtain a sharp trace
with adequate intensity.
8. L et the instrument warm up fo r at least
15 minutes before
changes or accurate observations.
V ariable Attenuator Balance
Adjustment
The need for adjustment of the VARIABLE
ATTE N . B AL. control is indicated by a vertical
shift in the position of the trace as the VARIABLE
(VOLTS/CM) control is rotated.
The Type L Unit has a separate VARIABLE
ATTE N . B A L. control for
am plifiers in the unit.
section VARIABLE
adjusts the dc balance between the two outputs
of the am plifier. The X10 VARIABLE ATTEN.
B A L. control adjusts the dc level of the X10
am plifier output to match that of the F irst
Cathode F ollow er, so that the trace position
w ill not shift when changing from X10 GAIN
AC to either of the other positions of the
AC-DC switch. Check these adjustments in
the following order:
1. Set the front panel controls as previously
listed. With no signal applied to the INPUT
of the plug-in unit, freerun the trace with
the S T A B ILIT Y and TRIGGERING LE V E L con­
trols fully clockwise.
at AC. Turn the VARIABLE
and forth, watching the
position of the trace.
when the control is rotated, adjust the upper
VAR IAB LE ATTEN.
trace position is no longer affected by the
V AR IAB LE control.
2. Turn the AC-DC switch to X10 GAIN AC.
Check the dc balance of the X10 am plifier
by rotating the VARIABLE control back and
forth. If the trace
VAR IABLE ATTEN. B AL. control until rotation
AA
are unlit, the trace
control clockwise
ASTIGMATISM and
making any adjustment
each of the two
The main am plifier
ATTEN. B AL. control
Set the AC-DC switch
control back
crt for a shift in
If the trace moves
B AL. control until the
moves, adjust the X10
Operating Instructions - Type L Plug-In
o f the VARIABLE control no longer affects
the position of the trace. Return the VARIABLE
control to the CALIBRATED position, fully
clockwise.
Checking Gain Adjustment
Adjustment of the vertical gain should be
checked frequently. Aging of tubes and other
components causes a slight change in the gain
characteristics of the plug-in.
make correct voltage measurements, adjust­
ment of the gain must be correct.
The Type L Unit has two screw driver adjust­
ments on the front panel fo r setting gain--one
fo r each am plifier in the unit. Checking the
gain is done in two steps:
1. With the oscilloscope and L Unit controls
positioned as above, set the oscilloscope C A L I­
BRATOR output fo r .2 VOLTS.
VAR IABLE (VOLTS/CM) is in CALIBRATED
position. Connect a lead from the output con­
nector of the CALIBRATOR
connector of the Type
S T A B ILIT Y and TRIGGERING LEVEL controls
of the oscilloscope
the CALIBRATO R square wave. The peak-to-
peak vertical deflection should be exactly four
m ajor graticule divisions (4cm). If incorrect,
adjust the upper GAIN
a small screw driver
amplitude.
2. With all other controls positioned as in
the previous step, turn the CALIBRATOR to
20 M ILLIVO LTS and set the AC-DC switch
in the X10 GAIN AC position.
S T A B ILIT Y and TRIGGERING LE VE L controls
to obtain a stable square-wave display. Check
the waveform for exactly 4 major graticule
divisions (4cm) of vertical deflection. If the
amplitude is not correct, adjust the X10 GAIN
ADJUST control until exactly 4 cm peak-to-
peak is observed. Remove the lead from the
L Unit INPUT.
IN P U T Coupling
F or measurement of dc voltage levels or
signal -to-ground voltages, it is necessary to
have dc-coupling throughout the measuring
instrument. With the
position, the oscilloscope/Type L Unit com­
bination is dc-coupled throughout.
In order to
Be sure the
to the INPUT
L Unit. Adjust the
for a stable display of
ADJUST control with
to obtain the proper
Adjust the
AC-DC switch in DC
2-3