Tektronix 475 schematic
*TB 9-6625-2240-35
DEPARTMENT OF THE ARMY TECHNICAL BULLETIN
CALIBRATION PROCEDURE FOR
OSCILLOSCOPE
OS261U (TEKTRONIX, TYPE 475),
OS261A(V)1U (TEKTRONIX, TYPE 475 OPTION 7),
OS261B(V)1U (TEKTRONIX, TYPE 475 OPTION 4),
OS261C(V)1U (TEKTRONIX, TYPE 475 OPTION 4/7),
TEKTRONIX, TYPE 475A (TEKTRONIX,
Headquarters, Department of the Army, Washington, DC
20 August 2001
Approved for public release; distribution is unlimited.
REPORTING OF ERRORS AND SUGGESTED IMPROVEMENTS
You can help improve this publication. If you find any mistakes or if you know of a
way to improve the procedure, please let us know. Mail your letter or DA Form 2028
to: Commander, U. S. Army Aviation and Missile Command, ATTN: AMSAM-MMCMA-NP, Redstone Arsenal, AL 35898-5230. A reply will be furnished to you. You may
also send in your comments electronically to our e-mail address:
2028@redstone.army.mil, or FAX 256-842-6546/DSN 788-6546
Paragraph Page
SECTION I. IDENTIFICATION AND DESCRIPTION
Test instrument identification ..........................
Forms, records, and reports ..............................
Calibration description ......................................
II. EQUIPMENT REQUIREMENTS
Equipment required ..........................................
Accessories required .........................................
Preliminary instructions ...................................
Equipment Setup ..............................................
Vertical deflection..............................................
Main sweep timing ............................................
Delay time and differential time measurement..
Risetime and bandwidth.....................................
Calibrator..........................................................
Power Supply ....................................................
Final procedure.................................................
III. CALIBRATION PROCESS
TYPE R475A)
1 2
2 2
3 2
4 3
5 3
6 4
7 4
8 5
9 8
10 12
11 15
12 20
13 22
14 23
AND
__________
*This bulletin supersedes TB 9-6625-2240-35, dated 7 November 1990.
TB 9-6625-2240-35
SECTION I
IDENTIFICATION AND DESCRIPTION
1. Test Instrument Identification. This bulletin provides instructions for the
calibration of Oscilloscope, OS261U (Tektronix, Type 475), OS261A(V)1U (Tektronix,
Type 475 Option 7), OS261B(V)1U (Tektronix, Type 475 Option 4), OS261C(V)1U
(Tektronix, Type 475 Option 4/7) and Tektronix, Type 475A (Tektronix, Type R475A).
The manufacturer's manuals were used as the prime data sources in compiling these
instructions. The equipment being calibrated will be referred to as the TI (test
instrument) throughout this bulletin.
a. Model Variations. Model variations are identified in the text.
b. Time and Technique. The time required for this calibration is approximately 4
hours, using the dc and low technique.
2. Forms, Records, and Reports
a. Forms, records, and reports required for calibration personnel at all levels are
prescribed by TB 750-25.
b. Adjustments to be reported are determined (R) at the end of the sentence in
which they appear. When adjustments are in tables the (R) follows the designated
adjustment. Report only those adjustments made and designated with (R).
3. Calibration Description. TI parameters and performance specifications which
pertain to this calibration are listed in table 1.
Table 1. Calibration Description
Test instrument
parameters
Vertical deflection Range: 2 mV/div to 5 V/div in 11 steps (5 mV/div to 10 V/div for Tektronix, Type 475A)
Accuracy: ±3% with gain set at 5 mV/div
Time and linearity
A sweep or B
DLY’D sweep
A delaying sweep
(A intensified
sweep)
Range: Unmag: 0.5 s/div to 0.01 µs/div in 24 steps
Mag: 0.5 s/div to 1 ns/div in 24 steps
Accuracy: 5 ms/div to 0.01 µs/div
Unmag: ±1%
Mag: ±2% 0.5 s/div to 10 ms/div
Unmag: ±2%
Mag: ±3%
Range: 0.5 s/div to 0.05 µs/div in 22 steps
Accuracy: Unmag: ±2%
Mag: ±3%
Performance specifications
2
TB 9-6625-2240-35
Table 1. Calibration Description - Continued
Test instrument
parameters
Delay time and
differential time
measurement
Risetime Range: 1.75 ns with aberrations not to exceed +4% or -4%, and total p-p of 4%
Bandwidth Dc to 200 MHz (Dc to 250 MHz for Tektronix, Type 475A)
Calibrator Range: 300 mV, ±l%
Range: 5 s to 0.05 µs after start of delaying A sweep
Accuracy: ±0.01 major dial divisions between dial settings of one major division or less
over entire range
(1.4 ns for Tektronix, Type 475A)
±1% between dial settings of more than 1 major dial division, increasing to
Performance specifications
±
0.5%
SECTION II
EQUIPMENT REQUIREMENTS
4. Equipment Required. Table 2 identifies the specific equipment to be used in this
calibration procedure. This equipment is issued with Secondary Transfer Calibration
Standards Set AN/GSM-286. Alternate items may be used by the calibrating activity.
The items selected must be verified to perform satisfactorily prior to use and must bear
evidence of current calibration. The equipment must meet or exceed the minimum use
specifications listed in table 2. The accuracies listed in table 2 provide a four-to-one
ratio between the standard and TI.
5. Accessories Required. The accessories required for this calibration are common
usage accessories, issued as indicated in paragraph 4 above, and are not listed in this
calibration procedure. The following peculiar accessory is also required for this
calibration: 5-80 pF standardizer.
Table 2. Minimum Specifications of Equipment Required
Common name
OSCILLOSCOPE
CALIBRATOR
DIGITAL
MULTIMETER
Minimum use specifications
Voltage output:
Range: 12 mV to 60 V
Frequency: 1 kHz
Accuracy: ±0.75%
Time markers:
Range: 1 ns to 0.5 s
Accuracy: ±.25%, .01 µs to 5 ms
±0.5%, 10 ms to 0.5 s
Risetime: 437.5 ps
Aberrations: ±1%
Level sine wave:
Reference frequency: 50 kHz
Amplitude: 30 mV
Capacity: >200 MHz
Voltage input:
Range: -15.23 to +113 V dc
Accuracy: ±.375%
John Fluke, Model 5820A, (5820A-5C-GHZ),
MIS-38938
John Fluke, Model 8840A/AF-05/09,
(AN/GSM-64D)
Manufacturer and model
(part number)
3
TB 9-6625-2240-35
SECTION III
CALIBRATION PROCESS
6. Preliminary Instructions
a. The instructions outlined in paragraphs 6 and 7 are preparatory to the
calibration process. Personnel should become familiar with the entire bulletin before
beginning the calibration.
b. Items of equipment used in this procedure are referenced within the text by
common name as listed in table 2.
c. Unless otherwise specified, verify the result of each test and, whenever the test
requirement is not met, take corrective action before continuing with this calibration.
Adjustments required to calibrate the TI are included in this procedure. Additional
maintenance information is contained in the manufacturer's manual for this TI.
d. When indications specified in paragraphs 8 through 12 are not within tolerance,
perform the power supply check prior to making adjustments. After adjustments are
made, repeat paragraphs 8 through 12. Do not perform power supply check if all other
parameters are within tolerance.
e. Unless otherwise specified, all controls and control settings refer to the TI.
7. Equipment Setup
WARNING
HIGH VOLTAGE is used or exposed during the performance
of this calibration. DEATH ON CONTACT may result if
personnel fail to observe safety precautions. REDUCE
OUTPUT(S) to minimum after each step within the
performance check where applicable.
a. Remove TI protective cover as required for adjustment.
b. Position CH1 and CH2 controls as listed in (1) through (7) below:
(1) FOCUS, vertical POSITION, and SCALE ILLUM controls to midrange.
(2) VOLTS/DIV switches to 5 m (10 m for Tektronix, Type 475A) and VAR
controls fully cw (detent).
(3) VERT MODE CH1 pushbutton pressed (in).
(4) AC-GND-DC switches to GND.
(5) INTENSITY control fully ccw.
(6) INVERT pushbutton out.
4
TB 9-6625-2240-35
(7) 20 MHz BW/TRIG VIEW pushbutton pressed in and released to full
bandwidth.
c. Position A and B triggering controls as listed in (1) through (7) below:
(1) A TRIGGER LEVEL control to 0 and SLOPE switch to + (positive).
(2) B (DLY'D) TRIGGER LEVEL control to 0 and SLOPE switch to + (positive).
(3) A TRIGGER SOURCE switch to NORM.
(4) B TRIGGER SOURCE switch to STARTS AFTER DELAY.
(5) A and B triggering COUPLING switches to AC.
(6) TRIG MODE AUTO pushbutton pressed (in).
(7) A TRIG HOLDOFF switch to NORM.
d. Position TI A and B sweep controls as listed in (1) through (5) below:
(1) A and B TIME/DIV switches to 1 ms and VAR control fully cw (detent).
(2) HORIZ DISPLAY A (A LOCKS KNOBS for all models SN B250000 and
above) pushbutton pressed (in).
(3) DELAY TIME dial to 0.00.
(4) X10 MAG pushbutton out.
(5) Horizontal POSITION (FINE) controls to midrange.
e. Connect TI to ac power source.
f. Pull POWER switch to ON and allow at least 20 minutes for warm -up.
g. Adjust INTENSITY, FOCUS, and ASTIG controls for suitable display.
8. Vertical Deflection
a. Performance Check
(1) Ensure CH1 VOLTS/DIV switch is set to 5 m (10 m for Tektronix, Type
475A).
(2) Adjust CH1 POSITION control to align trace on center horizontal graticule
line.
(3) Set CH1 VOLTS/DIV switch to 2 m (5 m for Tektronix, Type 475A). If trace
does not remain aligned with center horizontal graticule line, adjust R135 (fig. 1) to align
trace with center horizontal graticule line.
(4) Repeat (1) through (3) above for minimum trace shift when changing CH1
VOLTS/DIV switch from 5 m to 2 m (10 m to 5 m for Tektronix, Type 475A).
(5) Press VERT MODE CH2 pushbutton.
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TB 9-6625-2240-35
(6) Repeat technique of (1) thr ough (4) above using CH2 POSITION control and
adjusting R235 (fig. 1).
(7) Press VERT MODE CH1 pushbutton and set CH1 AC -GND-DC switch to
DC.
(8) Set CH1 VOLTS/DIV switch to 2 m (5 m for Tektronix, Type 475A) and
connect TI CH1 to oscilloscope calibrator CHAN 1.
(9) Press oscilloscope calibrator VOLTAGE pushbutton to illuminate green LED
and set frequency to 1 kHz.
6
Figure 1. Left side view.
TB 9-6625-2240-35
(10) Perform steps a through c below:
(a) Use technique of (b) and (c) below for TI VOLTS/DIV switch settings and
oscilloscope calibrator VOLTAGE outputs listed in table 3.
(b) Rotate CH 1 POSITION knob to center trace on TI crt.
(c) Rotate oscilloscope calibrator knob located below EDIT FIELD
pushbutton to obtain 6 divisions of vertical display. Oscilloscope calibrator err display
will indicate within limits specified in table 3; if not, perform b below.
Table 3. Channel 1 Vertical Deflection Accuracy
1
Test instrument
VOLTS/DIV
Switch settings
2 m 12 mV 3
5
10 m 60 mV 3
20 m 120 mV 3
50 m .3 V 3
.1 V .6 V 3
.2 V 1.2 V 3
.5 V 3.0 V 3
1 V 6.0 V 3
2 V 12.0 V 3
5 V 30.0 V 3
10 V1 60.0 V 3
For Tektronix, Type 475A.
1
m 30 mV 3
Oscilloscope calibrator
Voltage output
Oscilloscope calibrator
Err display limits
(±%)
(11) Move TI connection from CH1 to CH2.
(12) Press VERT MODE CH2 pushbutton and set CH2 AC -GND-DC switch to
DC.
(13) Set CH2 VOLTS/DIV switch to 2 m (5 m for Tektronix, Type 475A).
(14) Press oscilloscope calibrator VOLTAGE pushbutton to illuminate green LED
and en sure frequency is set to 1 kHz.
(15) Perform steps (a) through (c) below:
(a) Use technique of (b) and (c) below for TI VOLTS/DIV switch settings and
oscilloscope calibrator VOLTAGE outputs of those listed in table 4.
(b) Rotate TI CH 2 POSITION knob to center trace on crt.
(c) Rotate oscilloscope calibrator knob located below EDIT FIELD
pushbutton to obtain 6 divisions of vertical display. Oscilloscope calibrator err display
will indicate within limits specified in table 4.
7
TB 9-6625-2240-35
Table 4. Channel 2 Vertical Deflection Accuracy
1
Test instrument
VOLTS/DIV
switch settings
2 m 12 mV
51 m 30 mV
10 m 60 mV
20 m 120 mV
50 m .3 V
.1 V .6 V
.2 V 1.2 V
.5 V 3.0 V
1 V 6.0 V
2 V 12.0 V
5 V 30.0 V
10 V1 60.0 V
For Tektronix, Type 475A.
Oscilloscope calibrator
Voltage output
Oscilloscope calibrator
Err display limits
± %
3
3
3
3
3
3
3
3
3
3
3
3
b. Adjustments. Set oscilloscope calibrator to required parameter listed in table 5
for particular TI you are calibrating. Perform appropriate adjustments listed in table 5
for 6 divisions of vertical display on TI.
Table 5. Adjustment Guide
Parameter
(mV gain)
2 475 Below B250000 CH 1 R125
2 475 B250000 and up CH 1 R195
5 475 All SN’s CH 1 R165
5 475A --- CH 1 R195
10 475A --- CH 1 R165
Tektronix
type
Serial number
Adjustments
(fig. 1) (R)
CH 2 R225
CH 2 R295
CH 2 R265
CH 2 R295
CH 2 R265
9. Main Sweep Timing
NOTE
For oscilloscopes with digital multimeters attached, refer to
calibration section of digital multimeter manual at this point.
a. Performance Check
(1) Press VERT MODE CH1 pushbutton and set VOLTS/DIV switch to .5 V.
(2) Perform steps (a) through (d) below:
(a) Press oscilloscope calibrator MARKER pushbutton to illuminate green
LED and ensure oscilloscope calibrator output is set to 1.000 ms.
(b) Connect oscilloscope calibrator CHAN 1 to TI CH1 through 50Ω
termination.
8
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