Tektronix L3 User manual

Tektronix, Inc.
P.O. Box 500
Beaverton, Oregon 97077
070-2154-02
I~ktronoo
COMMITTEDTO EXCELLENCE
PLEASE CHECK FOR CHANGE
INFORMATION AT THE REAR
OF THIS MANUAL.
INSTRUCTION MANUAL
First Printing SEP 1976
Serial Number ----- Revised MAY 1981
Scans by ARTEK MEDIA =>
"
#.

Copyright © 1976,1977,1978 Tektronix, Inc. All
rights reserved. Contents of this publication may
not be
reproduced in any form without the written
permission of Tektronix, Inc.
Products of Tektronix, I nco and its subsidiaries
are covered by U.S. and
foreign patents and/or
pending patents.
TEKTRONIX, TEK, SCOPE-MOBILE, and ~
are registered trademarks of Tektronix, Inc.
TELEQUIPMENT is a registered
trademark of
Tektronix U.K. Limited.
Printed in U.S.A.
Specification and price change
privileges are reserved.
Scans by ARTEK MEDIA =>

TABLE OF
CONTENTS
P ...
P ...
Section 1 GENERAL INFORMATION Section 3 PERFORMANCE
CHECK
DESCRIPTION 1-1 INTRODUCTION 3-1
ELECTRICAL CHARACTERISTICS 1-1 eQUIPMENT REQUIRED 3-2
ENVIRONMENTAL
PROCEDURE 3-3
CHARACTERISTICS 1-4 Section 4 SERVICE
INFORMATION & DIAGRAM
Section 2 OPERATING INSTRUCTIONS
INTRODUCTION 4-1
INTRODUCTION
2-1 CALIBRATION PROCEDURE 4-2
INST ALLA TION
2-1
CIRCUIT DESCRIPTION 4-6
FRONT PANEL CONTROLS
COMPONENT LOCATIONS 4-9
AND CONNECTOR
2-1
SCHEMATIC DIAGRAM 4-13
INITIAL CALIBRATION
2-2
INPUT IMPEDANCE CHANGE
USING THE ANALYZER 2-3 PROCEDURE 4-18
Impedance
Matching
2-3 Section 5 REPLACEABLE PARTS
LISTS
5-1
Signal Amplitude
2-3 Accessories 5-18
USING THE L3 OPTION 1
WITH BALANCED
Section 6 OPTIONS
CONNECTIONS
2-4 L3
Option 1 6-1
REV. B APR 1978
L3
ScIUlS by ARTEK MEDIA =>

GENERAL INFORMATION
DESCRIPTION
The L3 Plug-In Moduleis one of aseries of modulesthat
are used with
the Tektronix 7L5 Spectrum Analyzer to
provide
it with various front end capabilities. The L3 has a
switch-selectable input termination: 500,6000, or ahigh
impedance
(1 MO/28 pF) probe compatible input.
Options for the L3 are described in the Optionssection.
ELECTRICAL CHARACTERISTICS
The following electrical characteristics applywhen the
L3 Plug-In Module, in
combination with a 7L5 Spectrum
Analyzer, is installed in a 7000-Series oscilloscope, and
has had a
warm-up period of ten minutes or more.
Intermodulation Distortion
With two on-screen signals within any frequency span
and
of any amplitudes, intermodulation distortion is at
least 75 dB down for third-order products and at least
72 dB down for second-order products.
With two on-screen signals and reference levels
of
-53 dB or less, intermodulation distortion is at least80 dB
down.
With two
out-of-band (>5 MHz) signals equal to or less
than the reference level, second-order intermodulation
products are at least 50 dB down.
With the INPUT BUFFER switch on, second- and
third-
order intermodulation products for any two on-screen
signals within anyfrequency span are at least80 dB down.
Sensitivity
The following tabulation of input noise for each
resolution bandwidth is measured with: 1) an L3 Plug-In
Module installed;
2) the INPUTBUFFER off; 3) theVIDEO
PEAKIVIDEO AVERAGE
control at maximum clockwise
position; 4) the TIME/DIV control set at 10 s; 5) DIGITAL
STORAGE DISPLAY A and Bon; 6) the input impedance
switch
at 50 O.
REV. A, OCT.1977
Section 1-L3
1-1
Scans by ARTEK MEDIA =>

Resolution Bandwidth
10 Hz
30 Hz
100 Hz
300 HZ
1 kHz
3 kHz
10 kHz
30 kHz
Equivalent Input Noise
(equal to or less than)
-148 dBV
-146 dBV
-143 dBV
-138 dBV
-133 dBV
-128 dBV
-123 dBV
-118dBV
NOTE
Sensitivity is degraded an additional 8 dB when the
INPUT BUFFER is on (illuminated): e.g., at 3 kHz,
the
equivalent noise would be -120 dBV instead of
-128 dBV. Norse level will increase by approxi-
mately 10 dB when operation is in the Video Peak
mode.
Range
MODE
50n
LOG 2 dB/DIV -128 dBm to +21 dBm
LOG 10 dB/DIV -70 dBm to +21 dBm
Residual Response
Internally generated spurious signals are -143 dBV or
less (referred to the input), or -138 dBV or less for
calibrator harmonics.
Display Flatness
Maximum peak-to-peak amplitude variation is 0.5 dB
from 25 Hz to 5 MHz, or 0.75 dB from 20 Hz to 5 MHz, plus
quantization error if digital storage is used (see 7L5
specifications) .
Reference Level
In the log mode, reference level refers to the top
horizontal graticule line and is calibrated in 1 dB and
10 dB steps.
600n
High Z
-139 dBm to +10 dBm
-141 dBV to +8 dBV
-81 dBm to +10 dBm
-83 dBV to +8 dBV
1-2
General Information-L3
@
SCfDIS byARTEK MEDIA =>

With operation in LIN mode, reference level calibration
range is from 20 nV/div to 200 mV/div, within 5%, in a 1-2-5
sequence. A variable reference level
control, VAR, can be
used
to increase the display amplitude by ~8 dB.
NOTE
A > sign is displayed adjacent to the reference level
readout when the reference level is not calibrated
due to an incompatible selection of the REFERENCE
LEVEL,
FREQUENCY SPAN/DIV, and TlME/DIV
controls.
Incremental Accuracy
Within 0.2 dB for any 1 dB change of reference level,
with cumulative error of 0.25 dB for any change up to
10 dB.
Within 0.25 dB/10 dBforanychangeof10 dBormore.
Input Connector
The INPUT connector is a three-conductor bnc con-
nector with the outer ring used to detect the presence of a
10X probe so that the reference level readout is changed
by 10X (+20 dB).
NOTE
Readout changes by a factor of only 10X if a 100X
probe is connected.
Input Impedance: Switch selectable; 1 MO in parallel
with 28 pF, 50 0 termination, or 600 0 termination.
Maximum Input Levels
1 MO/28 pF: 15 V pop for ac or pulse signals with
risetimes of 2 V//-ls or faster (pulses or ac beyond this
specification may open an input fuse).
@ General
Information-L3
1-3
Scans by ARTEK MEDIA =>

40 V (dc plus ac) for signals with risetimes slowerthan
2 VI f.1S.
600 n (internally terminated): 12 V dc or rms
(+24 dBm).
50 n (internally terminated):3.5 V dc or rms (+24 dBm).
ENVIRONMENTAL CHARACTERISTICS
The L3 Plug-In Module will meet the foregoing elec-
trical characteristics
when installed in a 7L5 Spectrum
Analyzer within the environmental limits of a 7000-Series
oscilloscope.
Complete details on environmental test
procedures including failure criteria etc., can be obtained
from your local Tektronix Field Office or representative.
1-4 General
Information-L3
REV A NOV 1980
Scans by ARTEK MEDIA =>

OPERATING INSTRUCTIONS
INTRODUCTION
This section of the manual contains installation instruc-
tions for the L3 plug-in, describes the function of its front
panel controls and connectors, and includes general
operating information suchas initial calibration and signal
application.
INSTALLATION
Visually inspect the 7L5 plug-in cavity to verify the
absence
of any obstruction such as misplaced internal
cables
or packing materials such as cardboard or
styrofoam. Carefully inspect the L3 module to ensure that
the cover plate is properly fastened with no protruding
screw heads.
~
Never install the L3 Plug-In Module without its cover
plate. The metal grounding fingers within the 7L5
cavity will catch and be severely damaged when the
plug-in is removed.
Align the L3 module in front of the 7L5 plug-in
aperature with its edge card connector to the rearand the
dBV/dBm switch tothe right. Carefullyslidethe L3 into the
7L5 plug-in cavity and apply a steady pressure to the L3
front panel until its rear connector is firmly seated and its
front panel is approximately flush with the7L5 front panel.
FRONT PANEL CONTROLS
AND CONNECTOR
AMPL CAL
The AMPL CAL control is a potentiometer that is
adjusted
during theOperational Check tocalibrate the full
screen reference level. This control is used tocompensate
for gain differences in the RF and IF portions of the
instrument. The
AMPL CAL control should be adjusted or
checked for proper setting each time the L3 Plug-In
Module is installed in a 7L5. (Refer to Initial Calibration
Section, which follows.)
INPUT TERMN Z
This three-position switch selects input termination of
50 0, 600 0, or the unterminated input of 1 MO in parallel
with 28 pF.
REV. A APR.1978
Section 2-L3
2-1
Scans by ARTEK MEDIA =>

INPUT REF
This three-position switch selects the reference level
scale factor:
dBm for 50 n, dBm for 600 n, or dBV. This
switch is independent
of the INPUT TERMN Z selection.
INPUT
This three-conductor bnc connector uses the outer
ring to detect the presence of a 10X probe, so that the
readout changes
by a factor of 10X (+20 dB).
NOTE
A 100X probe will change the readout by a factor of
only 10X (20 dB) instead of 100X (40 dB).
INITIAL CALIBRATION
The following procedure correlates deflection sensi-
tivity
of the L3 Plug-In Module, the 7L5 Spectrum
Analyzer, and the oscilloscope mainframe. These steps
should be performed each time the L3 is installed in a7L5,
and each time the instruments are turned on.
a. With the L3 installed in a 7L5 and the 7L5 installed in
an oscilloscope mainframe,
apply ac power and allow a
10-minute warmup period.
b. Select mainframe Vertical Mode, Horizontal Mode,
and
Trigger Source (Right or Left) settings to correspond
with plug-in compartments occupied
by the 7L5.
c.
Connect the 7L5 CALIBRATOR signal to the INPUT
connector on the L3 front panel with a short length of
coaxial cable. Set the INPUT TERMN Z switch to 50 n,
and the INPUT REF switch to dBV.
d. Select the LOG 2
dB/DIV pushbutton and set the
FREQUENCY SPAN/DIV to 2 kHz, RESOLUTION to
3 kHz, and
TIME/DIV to 0.2 s. Switch the DISPLAY A and
DISPLAY B display processing selectors on. Adjust the
VERT POSITION to place the display on the bottom
horizontal graticule line.
e. Adjust the REFERENCE LEVEL to -40 dBV and set
the
DOT FREQUENCY to 500.00 kHz. Select the LOG 10
dB/DIV pushbutton and adjust the 7L5 LOG CAL control
for a full screen (8-division) display.
f. Select the LOG 2 dB/DIV display and adjust the L3
AMPL
CAL control for a full screen display.
g. Repeat steps e and f until the displayed waveform is
8 vertical divisions in both the 10
dB/DIV and 2 dB/DIV
modes. Refer to Fig. 2-1.
2·2 Operating Instructions-L3
REV. A APR 1978
Scans by ARTEK MEDIA =>

Fig. 2-1. Initial calibration waveform.
USING THE ANALYZER
Impedance Matching
When the L3 module is installed, the input impedance
of the 7L5 Spectrum Analyzer is determined by thesetting
of the INPUT TERMN Z switch. Impedance mismatch
between asignalsourceand the module's in~ut connector
causes reflections or standing waves in the interconnec-
ting transmission line. Standing waves at the
input
connector may cause amplitude errors in the display and
an overall degraded performance of the analyzer. To
minimize the probability
of an impedance mismatch, all
cables and transmission lines fastened
to the input
connector should have thesame impedance as the plug-in
module. All cables used should be of minimum length and
of good quality with connector center conductors not
worn,
protruding or recessed. Degraded display caused
by impedance mismatch may be improved by selecting
the 7L5's INPUT BUFFER control.
Signal Amplitude
High amplitude signals (refer to Electrical Char-
acteristics) should
not be applied to the INPUTconnector.
Signals of unknown amplitudeshould be routed througha
series attenuator. If spurious
or multitone inter-
modulation signals are present in the display, or if
saturation of the mixer is suspected, selectthe7L51NPUT
BUFFER. This control adds 8 dB of attenuation in series
with the
input signal, and compensates with 8 dB of
amplLfication in the 7L5. If thedisplayed signals show little
or no amplitude change with the buffer on, the inter-
modulation is probablygeing generated priortothe input.
If the displayed signals decrease in amplitude, they are
being generated within the analyzer
as a result of ex-
cessive
input signal amplitude.
REV. A APR 1978 Operating
Instructlons-L3
2-3
Scans by ARTEK MEDIA =>

USING THE L3 OPTION 1 WITH
BALANCED CONNECTIONS
Baseband telephony systems frequently utilizebalanc-
ed connections. This is accommodated by a balanced to
single-ended transformer, part number 013-0182-00. See
Fig. 2-2. Frequency range of the Balanced Transformer is
50 kHz to 3 MHz (useable from 10 kHz to 20 MHz).
Flatness is 0.25 dB peak-to-peak, including nominal
0.1 dB insertion loss, and a common mode rejection of
25 dB minimum (within the 50 kHz to 3 MHz range). The
transformer has a
three-position switch at the output to
provide a 124 n termination, a 135 n termination, and no
termination. Thus, an L3 Option 1in conjunction with the
accessory transformer provides all of the
common base-
band impedance levels (75
n, 600 n, 124 n, 135 n, and
1
Mn for bridging).
Balanced connections at 124 n or 135 n is ac-
complished by connecting the Balanced Transformer
between the balanced
connections and the L3 INPUT.
Switch the L3 INPUT TERMN Z to 1 Mn and the REF to
dBV. Switch the Balanced Transformer switch to the
desired impedance. The relationship between dBV and
dBm is: dBm = dBV -10 LogZ + 30, where Z equals the
terminating impedance. For the two impedancesprovided
on
the balanced transformer, the theoretical relationship
is: dBm (124
n) = dBV + 9.07, dBm (1350) = dBV + 8.7.
Since
the transformer has an insertion loss of less than
0.1 dB, the theoretical correction factors offer sufficient
accuracy.
Balance connection at other than 124 n or 135 n uses
the transformer in the unterminated position
with the
termination provided
either by the L3 or bya feed-through
termination connected between the transformer and 7L5
input. When the
termination is outside the 7L5, it is
necessary
to set the 7L5 in the 1 Mn bridging position so
as not to double terminate the connection. The reference
level should be set to dBV.
Fig. 2-2. Balance Transformer.
2-4
Operating Instructions-L3
REV. A APR 1978
Scans by ARTEK MEDIA =>

@
PERFORMANCE CHECK
INTRODUCTION
The following procedure verifies the electrical characteristics of the L3 Plug-In Module and
includes checks on intermodulation distortion, residual response, reference level accuracy, and display
flatness. Adjustments are not included; they are located in the Calibration Procedure in Section 4.
If the instrument fails to meeta performance requirement, refertothe related adjustment procedure
in this manual
or in the 7L5 manual.
Section 3-L3
Scans by ARTEK MEDIA =>
3-1

EQUIPMENT REQUIRED
Minimum Typical Model
Type Performance Requirements or Part No.
715 Spectrum Analyzer Plug-In
installed in a 7000-series mainframe
Signal Generators 10 kHz
to 5 MHz
Hewlett-Packard 654 or 651
+10 dBm to -89 dBm into 50 n
Signal Generators 10 MHz
to 125 MHz
Hewlett-Packard 8654
+5 dBm to -40 dBm into 50 n
Step Attenuator
1 dB/step
Tektronix 2701
Attenuators, 14 dB 50 n (2)
Tektronix 011-0060-02
Coaxial cables, 50 n (3)
Tektronix 012-0057-01
BNC T connector
Tektronix 103-0030-00
Cap, BNC non-shorting
Tektronix 200-0678-00 or
Tektronix 200-0685-00
3-2 Performance Check-L3
@
Scans by ARTEK MEDIA =>

PROCEDURE
1. Preliminary Steps
a. Install the L3 in the 7L5, and install the 7L5 in the
oscilloscope mainframe.
b.
Turn the instruments on and allow to warm upfor10
minutes or more.
c. Perform
the Initial Calibration procedure described
in Section 2 of this manual.
2. Check Readout
a. Set REFERENCE LEVEL to +21 dBm 50 O.
b. Switch INPUT REF to dBV and check for a readout
of +8 dBV. f' , ~, ~.
c. Switch INPUT REF to dBm 600 0 and check for a
readout of +10 dBm.
d. Momentarily connect a 10X probe to the INPUT, or
short circuit the INPUT connector ring to the shell, and
check that the readout increases by 20 dB.
3. Check Reference Level Accuracy
a. Set the front panel controls as follows:
DOT FREQUENCY 1 MHz
RESOLUTION COUPLED
FREQUENCY SPAN/DIV 10 kHz
INPUT REF dBV
REFERENCE LEVEL ~45 dBV; LOG 2 dB/DIV
TRIGGERING FREE RUN NORM
TIME/DIV AUTO
INPUT TERMN Z 50 0
b. Connect a HP 654 signal generator, through a 2701
Step Attenuator, to the L3 INPUT. Set the attenuators for
48 dB attenuation, then adjust thesignal generatorfor a7-
division display at 1 MHz.
c.
Setthe REFERENCE LEVELto ~37 dBV, setthestep
attenuator for 40 dB, and check for a display of 7 divisions
±0.1 division (0.2 dB).
d. Repeat the above procedure of adding 8 dB in the
7L5 and taking
out 8 dB in the step attenuators, up to
+3 dBV reference level. Check that the level ateach step is
within ±0.1 division of the level at the previous step.
Ie /( {"I/"/ , -,;! i' /'. . J.. I S ;'( ::-: 7, 96 ~'f1J
@ Performance
Check-L3
3-3
Scans by ARTEK MEDIA =>

4. Check Display Flatness
a. Set the front panel controls as follows:
DOT FREQUENCY 10.00 kHz
FREQUENCY
SPAN/DIV 20 kHz
INPUT REF dBm 50 n
REFERENCE LEVEL 0 dBm; LOG 2 dB/DIV
Leave all other controls as they were in thepreviousset-
up.
b. Connect a HP 654 signal generator to the input and
adjust it for a 7-division display at 10 kHz.
c. Simultaneously tune the signal generator
frequency
and the DOT FREQUENCY from 10 kHz to 5 MHz, and
check
that the display flatness is within 0.5 dB peak-to-
peak. \\
l(,1 \J
5. Check Third-Order Intermpdulation Distortion
a. Set the front panel controls as follows:
DOT FREQUENCY 4500.00 kHz
FREQUENCY
SPAN/DIV 5 kHz
RESOLUTION
INPUT REF
REFERENCE LEVEL
300 Hz
dBV
-38 dBV; LOG 10 dB/DIV
Leaveall other controls as theywere in the previousset-
up.
b. Connect two Signal generators, such as HP654 or
651, plus the attenuators, as shown in Fig. 3-1. Setthestep
attenuators
for 32 dB of attenuation, and adjustthe Signal
generators for two full-screen signals one division apart
(such as 4495 kHz and 4500 kHz).
NOTE
Some generators may produce cross talk when in
close
proximity to the unit. Separate and orientate
for best
1M. In some cases an isolated combiner or
directional bridge (e.g., HP Model 8721A) may be
desirable instead
of the attenuators shown in Fig.
3-1.
c. Check that the intermodulation sidebands are at
least 75 dB below the signals.
3-4 Performance
Check-L3
REV A, FEB 1979
Scans by ARTEK MEDIA =>

OSCILLOSCOPE
651
SIGNAL
GENERATOR
NO.1
0 r-L
5X(14 dB)
ATTENUATOR
son
'--~
BNC "T"
STEP
t--
ATTENUATOR
7L5
...---
5X(14 dB)
ATTENUATOR
son
'--r--
651 lo
L3 J
SIGNAL
GENERATOR
NO.2
0
2154-2
Fig. 3-1. Intermodulation distortion test equipment setup.
@ Performance
Check-L3
3-5
Scans by ARTEK MEDIA =>

6. Check Second-Order Intermodulation Distortion
a. Set one signal generator to 5 kHz, then repeat the
set-up and
procedure in step 5, checking that the inter-
modulation sidebands are at least 72 dB below the
signals.
7. Check Out-ot-Band Intermodulation Distortion
a. Set the front panel control as follows:
DOT FREQUENCY
REFERENCE LEVEL 4500.00 kHz
-14 dBV
Leave all other controls as theywere in the·previousset-
up.
b.
Connect two signal generators, such as HP8654, to
the L3 as indicated in Fig. 3-2. Set generator one to 10 MHz
and generator two to 14.5 MHz.
c.
Adjust the generators so that each signal is 560 mV
Pop at the L3 input. To do this: monitor theL3 input with an
oscilloscope, disconnect generator two, and terminate the
SIGNAL
GENERATOR
SIGNAL
GENERATOR
BNC
"T" L31NPUT
2154-3
Fig. 3-2. Test set-up for out-of-band intermodulation distortion.
cable into 50 n. Adjust generator one, then disconnect it,
terminate its cable into 50 n, and reconnect and adjust
generator two. Remove the termination and reconnect
generator one.
d.
Check that the display at 4500 kHz is more than
50 dB below the signals.
3-6 Performance
Check-L3
@
Scans by ARTEK MEDIA =>

e. Set the signal generators to the following frequen-
cies and repeat steps c and d:
8. Check Residual Response and Sensitivity
Refer to the 7L5 Instruction Manual and perform the
residual response and sensitivity checks found there, with
a non-shorting bnc cap installed on the INPUTconnector.
Make the checks
with the INPUT TERMN Z switch set to
both 1
MO/28 pF and 50 O.
20 MHz 24.5 MHz
40 44.5
60 64.5
75 79.5
90 94.5
120 124.5
@ Performance
Check-L3
3-7
Scans by ARTEK MEDIA =>