Tektronix TYPE L User manual

INSTRUCTION
MANUAL
Tektronix, Inc.
S.W. Millikan Way • P. O. Box 500 • Beaverton, Oregon • Phone Ml 4-0161 • Cable : Tektronix
Tektronix International A.G.
Terra enweg 1A • Zug, Switzerland • PH. 042-49192 • Cable: Tekintag, Zug Switzerland • Telex 53.574
070-336

All Tektronix in trument a re warranted
again t defective material and workman 
hip for one year. Tektronix tran former ,
manufactured in our own plant, are war 
ranted for the life of the in trument.
Any que tion with re pect to the war 
ranty mentioned above hould be taken up
with your Tektronix Field Engineer.
Tektronix repair and replacement-part
ervice i geared directly to the field, there 
fore all reque t for repair and replace 
ment part hould be directed to the Tek 
tronix Field Office or Repre entative in your
area. Thi procedure will a ure you the
fa te t po ible ervice. Plea e include the
in trument Type and Serial number with all
reque t for part or ervice.
Specification and price change priv 
ilege re erved.
Copyright © 1962 by Tektronix, Inc.,
Beaverton, Oregon. Printed in the United
State of America. All right re erved.
Content of thi publication may not be re 
produced in any form without permi ion
of the copyright owner.
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WARRANTY

AA
Type L
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CONTENTS
Warranty
Section 1 Characteri tic
Section 2 Operating In truction
Section 3 Circuit De cription
Section 4 Maintenance
Section 5 Calibration Procedure
Section 6 Part Li t and
Schematic

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01X1 1
CHARACTERISTICS
General Information
The Type L Plug-In is a fast-rise, high
gain, calibrated preamplifier designed for use
with the Tektronix 530-, 5 0-, 550- and *580-
Series oscilloscopes. The unit contains a fast 
rise d c amplifier similar to the Type K Plug 
*Type 81 Plug-In adaptor must be used with the 580-Series Oscilloscopes.
**Nanoseconds are 10~9 seconds.
In Unit, plus a fast-rise high-gain ac amplifier
which may be used to increase the sensitivity
by a factor of 10.
This instrument was adjusted at the factory
for best transient response. The L Unit alone
has a risetime of 6 nanoseconds in AC or
TABLE 1-1. TRANSIENT RESPONSE AND BANDPASS
Type
RISETIME in nanoseconds ** BANDPASS
L AC-DC
Unit switch AC or DC
X10 GAIN AC
DC
AC
X10 GAIN AC
Oscilloscope
Type:
70
70
DC to 5MC 3 cps to 5MC 3 cps to 5MC
532
5 1/5 1A
5 3/5 3A
5 5/5 5A
555
12 1 DC to 30MC
3 cps to 30MC 3cps to 2 MC
531/531A
533/533A
535/535A 23
32 DC to 15MC
3cps to 15MC 3cps to 11MC
*581
*585
12
1 DC to 30MC 3 cps to 30 MC 3cps to 2 MC
551
1 16 DC to 25MC
3cps to 25MC
3cps to 22MC
536 32 35
DC to 11MC 3cps to 11MC 3cps to 10MC
With X10 probes (Types P6017, P6000, P510, P 10) minimum AC response is reduced to 0.3 cps.
AA Characteristics - Type L Plug-In 1-1

DC and 10 nanoseconds in X10 GAIN AC.
Table 1-1 summarizes risetimes and frequency
responses available when the L Unit is used
in combination with various types of Tektronix
oscilloscopes.
Vertical Deflection Factors
AC or DC position of AC-DC switch: 0.05
to 20 volts per centimeter in nine calibrated
steps; also continuously variable (uncalibrated)
between steps, and up to 50 volts per centimeter.
X10 GAIN AC position of AC-DC switch: 0.005
to 2 volts per centimeter in nine calibrated
steps; also continuously variable (uncalibrated)
between steps, and up to 5 volts per centimeter.
Step Attenuator (VOLTS/CM switch)
Accurac
Within 3% of front-panel reading for all positions
of VOLTS/CM switch.
Input Impedance Characteristics
Type L Plug-In Unit: 1 Megohm shunted by
20 picofarads.
Type P6017 Probe: 10 Megohms shunted by
1 picofarads.
Type P6000 Probe: 10 Megohms shunted by
11.5 picofarads.
Type P510 Probe: 10 Megohms shunted by
1 picofarads.
Type P 10 Probe: 10 Megohms shunted by
8 picofarads.
Maximum Allowable Combined DC
and Peak AC Input
600 volts, ac-coupled.
Mechanical
Construction: Aluminum-alloy chassis.
Finish: Photoetched, anodized front panel.
Weight: Approximately 5 pounds.
1-2
Characteristics - Type L Plug-In
AA

01X1 2
OPERATING
INSTRUCTIONS
Markings and Functions of Controls
The functions of the controls should be
understood before operating the L Unit. This
section of the Instruction Manual is intended
to aid in initially putting the instrument into
operation and to serve as a brief reference
guide. Figure 2-1 shows the front-panel con 
trols, connectors and adjustments of the Type
L Plug-In Unit and describes their functions.
In this Manual, control and adjustment mark 
ings are given as printed on the instruments,
with fully capitalized words used for front 
panel markings, and first-letters capitalized
for names of internal adjustments. Examples:
VERTICAL POSITION control; H.F. Peaking
control.
On the front panel of the L Unit , red markings
are related to the red VARIABLE knob, blue
and black markings are related to the black
knobs. The black-numbered scale around the
VOLTS/CM switch is used when the AC-DC
switch is in AC or DC position, and the blue
scale is used when the AC-DC switch is in
X10 GAIN AC position.
In the following procedures, oscilloscope
controls are called by the names usually applied
to them on the scopes with which the Type L
Unit can be used. Alternate names for the
controls are given in parentheses.
First-Time Operation
To set the oscllloscope/Type L Plug-In Unit
combination in operation for the first time
the following procedure is suggested:
1. Insert the Type L Unit into the plug-in
compartment of the oscilloscope and tighten
it with the securing rod.
2. Set the front-panel controls as follows (con 
trols not mentioned may be in any position):
Oscilloscope:
POWER off
INTENSITY
fully counter 
clockwise
HORIZONTAL DISPLAY NORMAL (" A" ,
INTERNAL
SWEEP)
MAGNIFIER (5X MAG.)
OFF
Main Sweep Controls:
TIME/CM .5 MILLISEC
VARIABLE, TIME/CM CALIBRATED,
fully clockwise
TRIGGER SLOPE -INT. (-)
TRIGGERING MODE
AC (AC SLOW)
(TRIGGERING SOURCE) (INT.)
STABILITY fully clockwise
TRIGGERING LEVEL
fully clockwise
Type L Plug-In Unit:
AC-DC DC
VOLTS/CM .05 (black
numbers)
VARIABLE, VOLTS/CM
CALIBRATED,
fully clockwise
3. Connect the power cord to the instrument
and to the source of power.
. Turn ON the POWER switch. Allow a minute
for the filaments to heat
and the time-delay
relay to operate.
5. Before increasing the intensity, center the
trace vertically with the VERTICAL POSITION
control, using the Beam
Indicator neons of
the oscilloscope as a guide.
(When both vertical
AA Operating Instructions - Type L Plug-In
2-1

VOLTS/CM — Nine -
po ition witch elect
calibrated vertical
en itivitie indicated on
panel. Black number
u ed for AC and DC; blue
number for x10 GAIN
AC.
VARIABLE -- Control
provide continuou ly
variable attenuation be 
tween tep of VOLTS/
CM witch. Extend
attenuation to provide
en itivity to 50 V /cm i n
AC and DC; to 5 . 0v/cm
in x 10 G AIN AC.
AG-DC--Thr e e - po ition
witch provide d c 
coupling in DC po ition.
ac- co upling in x10 GAIN
AC and AG po ition . x10
GAIN AC po ition al o
witche x10 amplifier
into circuit.
Ground--Connector for
grounding other equip 
ment t o cha i of plug
in unit.
INPUT UHF - type
ignal input connector.
TYPE L
PLUG-IN UNIT
SERIAL
VARIABLE
VOLTS/CM
ATTEN.
GAIN ADJUST Screw 
driver- adju table con 
trol eta gain of main-
amplifier ection of the
unit.
GAIN ADJUSL--
Screwdriver adju t 
able control et gain
of X10 amplifier ec 
tion.
VERTICAL POSITION -
- Control
o cillo cope
vertically.
po ition
di play
2-2
VERTICAL
foiinoiv
VARIABLE
BAL, Screwdriver
ad ju table control bal 
ance main-amplifier
ection o that u e of
VARIABLE control doe
not hill o cillo cope
di play.
VARIABLE ATTEN.
BAL, - Screwdriver
adju table control bal 
ance X 10 amplifier out
put o that u e of
VARIABLE control doe
not hift o cillo cope d i -
play.
Fig. 2'1. Functtorts of front-panel controls and connectors of the Type L Plug Jn Unit.
Operating Instructions Ivpc L Plug-In
A.A
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Beam Indicator neons are unlit, the trace
is approximately centered.
6. Rotate the INTENSITY control clockwise
until the free-running trace appears on the
crt. Center the trace with the vertical and
horizontal positioning controls.
7. Adjust the FOCUS, ASTIGMATISM and
INTENSITY controls to obtain a sharp trace
with adequate intensity.
8. Let the instrument warm up for at least
15 minutes before making any adjustment
changes or accurate observations.
Variable Attenuator Balance
Adjustment
The need for adjustment of the VARIABLE
ATTEN. BAL. 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
ATTEN. BAL. control for each of the two
amplifiers in the unit. The main amplifier
section VARIABLE ATTEN. BAL. control
adjusts the de balance between the two outputs
of the amplifier. The X10 VARIABLE ATTEN.
BAL. control adjusts the d c level of the X10
amplifier output to match that of the First
Cathode Follower, so that the trace position
will 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 STABILITY and TRIGGERING LEVEL con 
trols fully clockwise. Set the AC-DC switch
at AC. Turn the VARIABLE control back
and forth, watching the CRT for a shift in
position of the trace. If the trace moves
when the control is rotated, adjust the upper
VARIABLE ATTEN. BAL. control until the
trace position is no longer affected by the
VARIABLE control.
2. Turn the AC-DC switch to X10 GAIN AC.
Check the d c balance of the X10 amplifier
by rotating the VARIABLE control back and
forth. If the trace moves, adjust the X10
VARIABLE ATTEN. BAL. control until rotation
of 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. In order to
make correct voltage measurements, adjust 
ment of the gain must be correct.
The Type L Unit has two screwdriver adjust 
ments on the front panel for setting gain--one
for each amplifier 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 CALI 
BRATOR output for .2 VOLTS. Be sure the
VARIABLE (VOLTS/CM) is in CALIBRATED
position. Connect a lead from the output con 
nector of the CALIBRATOR to the INPUT
connector of the Type L Unit. Adjust the
STABILITY and TRIGGERING LEVEL controls
of the oscilloscope for a stable display of
the CALIBRATOR square wave. The peak-to-
peak vertical deflection should be exactly four
major graticule divisions ( cm). If incorrect,
adjust the upper GAIN ADJUST control with
a small screwdriver to obtain the proper
amplitude.
2. With all other controls positioned as in
the previous step, turn the CALIBRATOR to
20 MILLIVOLTS and set the AC-DC switch
in the X10 GAIN AC position. Adjust the
STABILITY and TRIGGERING LEVEL controls
to obtain a stable square-wave display. Check
the waveform for exactly major graticule
divisions ( cm) of vertical deflection. If the
amplitude is not correct, adjust the X10 GAIN
ADJUST control until exactly cm peak-to-
peak is observed. Remove the lead from the
L Unit INPUT.
INPUT Coupling
For measurement of de voltage levels or
signal -to-ground voltages, it is necessary to
have dc-coupling throughout the measuring
instrument. With the AC-DC switch in DC
position, the oscilloscope/Type L Unit com 
bination is dc-coupled throughout.
AA
Operating Instructions - Type L Plug-In
2-3

However, it is often neither necessary nor
desirable to display the de component of the
input waveform. A capacitor which is in series
with the INPUT connector blocks the de com 
ponent when the AC-DC switch is in either
the AC or the X10 GAIN AC position. This
permits viewing of the ac part of a large
input signal, as well as detailed viewing of
the ac part of any signal having adc component.
Connecting to the Signal Source
Stray electric and magnetic fields picked
up by unshielded connecting cables often change
the appearance of displayed waveforms. This
type of distortion occurs even in the audio 
frequency range, except possibly when making
measurements of low-impedance circuits. In
general, unshielded leads of appreciable length
are not suitable for connecting the input signal
to the plug-in INPUT. Shields of leads used
should be grounded to the chassis of the instru 
ment in use. Coaxial cables are recommended
for most purposes.
In broadband applications, it is usually neces 
sary to terminate a coaxial cable with a resistor
which presents a resistance equal to the charac 
teristic impedance of the cable. This prevents
the production of high-frequency damped oscil 
lation. As the length of the cable is increased
it becomes more important to properly ter 
minate the cable. The termination is placed
at the oscilloscope end of the cable, although
many sources require an additional termination
at the source end as well.
For large amplitude signals an attenuator
may be included in the connective system to
provide an oscilloscope display having a more
desirable amplitude than would be possible with
no attenuation. Cables, attenuators and ter 
minating resistors are listed in the Accessories
section of any Tektron i x oscilloscope Instruction
Manual.
When checking the instruments, actual operat 
ing conditions should be simulated as nearly
as possible. For example, the oscilloscope
should work into a load impedance similar to
that which it encounters in actual use.
The input circuit of the plug-in may some 
times produce loading of the signal source.
At the INPUT connector of the Type L, the
impedance of the input circuit is equivalent to
a resistance of 1 Megohm shunted with a
capacitance of 20 picofarads. With a few
feet of shielded cable, the capacitance may
well be increased to 100 picofarads. Where
the effects of these resistive and capacitive
loads is significant, a probe may be used
to introduce the input signal.
Use of Probes
An attenuator probe reduces both capacitive
and resistive loading of the signal source
and decreases apparent sensitivity of the oscil 
loscope. Attenuation by the probe permits
observation and measurement of signal voltages
in excess of those that can be accepted by
the preamplifier alone.
The 10X probes (P6017, P6000, P510A, P 10)
supplied with the oscilloscopes accepting letter 
series plug-ins may all be used with theL Unit.
Input characteristics of these probes are listed
in the Characteristics section of this Manual.
Maximum voltage which may be applied to
the probes is 600 volts dc-plus-peak-ac.
Exceeding this limit may result in damage
to the components inside the probe. The P510A
Probe can be used only from DC to 50MC,
due to the tendency for the probe to ring
at 50MC and above.
If the displayed waveform contains high-
frequency portions, it is generally necessary
to clip the probe ground lead to the chassis
of the equipment being checked.
Before using a probe, check its adjustment.
An adjustable capacitor in the body of the probe
is used to compensate for differences between
input capacitances of various instruments. To
insure the accuracy of pulse and waveform
measurements, the probe adjustment should
be checked when changing oscilloscopes, and
occasionally when used with any scope.
Probe Compensation
To adjust the compensation of the probe
to the instrument combination with which it
is to be used, the following procedure is
suggested:
1. Set the oscilloscope and plug-in controls as
listed above in First-Time Operation. Turn the
oscilloscope CALIBRATOR voltage selector to
2 VOLTS. Allow adequate time for the instru-
2-
Operating Instructions - Type L Plug-In
AA