Tektronix 180A User manual

I IM S T R U C T I O IM
I V I A I N I U A L Serial Number
Tektronix, Inc.
S.W . M illikan W ay • P. O. Box 500 • Beaverton, Oregon • Phone Ml 4-0161 • C ables: Tektronix
Tektronix International A .G .
Terrassenweg 1A • Zug, Switzerland • P H .0 4 2 -49 1 9 2 • C ab le : Tekintag, Zug Switzerland • Telex 53.574
070-358

W ARRANTY
All Tektronix instruments are warranted
against defective materials and workman
ship for one year. Tektronix transformers,
manufactured in our own plant, are war
ranted for the life of the instrument.
Any questions with respect to the war
ranty mentioned above should be taken up
with your Tektronix Field Engineer.
Tektronix repair and replacement-part
service is geared directly to the field, there
fore all requests for repairs and replace
ment parts should be directed to the Tek
tronix Field Office or Representative in your
area. This procedure will assure you the
fastest possible service. Please include the
instrument Type and Serial number with all
requests for parts or service.
Specifications and price change priv
ileges reserved.
Copyright© 1959. New material Copy
right© 1963 by Tektronix, Inc., Beaverton,
Oregon. Printed in the United States of
America. All rights reserved. Contents of
this publication may not be reproduced
in any form without permission of the
copyright owner.

CONTENTS
Warranty
Section 1 Characteristics
Section 2 Operating Instructions
Section 3 Circuit Description
Section 4Maintenance
Second 5Calibration Procedure
Section 6 Parts List and Schematics

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Type 180A

SECTION 1
CHARACTERISTICS
General
The Tektronix Type 180A Time-Mark Generator is a
portable laboratory instrument designed to provide accur
ate time marks, trigger pulses, and sine-wave outputs. The
Type 180A may be used in any application where accurate
measurement of short time intervals is necessary.
Output Characteristics
Microsecond markers at intervals of 1, 5, 10, 50, 100 and
500 microseconds.
Millisecond markers at intervals of 1, 5, 10, 50, 100 and
500 milliseconds.
One-second and five-second interval markers. Sine-waves
of 5 me, 10 me, and 50 me. Trigger pulses at rates of 1 cps,
lOcps, and 100 cps, 1 kc, lOkc and 100 kc.
The markers are available individually at banana jacks
on the front panel and at a front panel connector labeled
MARKER OUT. The individual push-button switches connect
the markers to a common bus, so that any or all of the
markers can be made available simultaneously at the
output. Push-button switches are also provided to connect
any one of the three sine-wave outputs to the MARKER
OUT connector. Only one sine-wave can be used at a
time.
Trigger pulses are available at the TRIGGER OUT
connector on the front panel of the Type 180A. The trigger
pulses are also selected by the operation of a push-button
switch.
TABLE 1-1
For Type 180A, S/N 5479 and up
NOM INAL VOLTAGE, IMPEDANCE, AND RISETIME VALUES
Open Circuit
Voltage
Impedance
(at half-voltage)
*Risetime Open Circuit
Voltage
Impedance
Markers 3 volt minimum 390 Q or less varies from 0.07
/xsec at 1 /xsec to
1.7 /xsec at 5
seconds
25 volts minimum
using 10X probe
390 Q at 1 /xsec
to 680 n at 5
seconds
Trigger
Pulses
6 volt minimum 56 Q or less 0.08 /xsec at 100
kc to 0.30 fxsec
at 1 cps
Sine
Waves
3 volt minimum
peak-to-peak
across 53-ohms
*With marker out and trigger out terminated in 93 ohms.
TABLE 1-1 S/N 5001-5478
NOMINAL VO LTAGE, IMPEDANCE AND RISETIME VALUES
Open Circuit
Voltage using
10X Probe
Impedance
(at half voltage)
*Risetime Open Circuit
Voltage using
10X Probe
Impedance
Time
Markers
1.5 V Min. 390 Q or less varies from 0.07
lxsec at 1 /xsec to
1.7 /xsec at 5 sec
8 V Min. 390 Q at 1 /xsec
to 680 a at 5 sec.
Trigger
Pulses
2.0 V Min. 56 Q or less 0.08 /xsec at 10
/xsec to 0.3 /xsec
at 1 sec.
Sine Waves
Using 50 Q
Terminator
5 & 10 MC— 2.5 V
50 MC— 1.5 V
1-1

Characteristics — Type 1 80A
Other Characteristics
Crystal O scillator
Frequency— 1 me ± 1 0 cp s. May be accurately set for
1 me. Stability— within 3 parts per million in 24 hours.
Power Requirem ents
117 or 234 V Nominal Line Voltage
50 to 60 cps, 240 watts.
M echanical Specification s
Ventilation— filtered, forced air.
Finish— photoetched, anodized panel. Blue vinyl, perfor
ated cabinet.
Dimensions— 13'/2" high, 93/4" wide, 17” depth.
Weight—31 pounds.
Accesso ries
2—Type P93 Coaxial Cables (012-003)
1—Type A 100 Clip-Lead Adapter (013-003)
1—3 to 2 wire adapter, (103-013)
1— 3 conductor power cord
2— Instruction manuals.
1-2

SECTION 2
OPERATING
INSTRUCTIONS
General
The Type 180A may be operated in any normal indoor
location, or in the open if protected from moisture. If the
instrument has been exposed to dampness, it should be
left in a warm room until thoroughly dry before being
placed in operation. Operation of the controls also helps to
keep the contact surfaces of the switches free from an
accumulation of dirt and tarnish.
Cooling
A fan maintains safe operating temperature in the Type
180A Time Mark Generator by circulating air through a
filter and over the components. Therefore, the instrument
must be placed so that the air intake is not blocked. The
air filter must be kept clean to permit adequate air circula
tion. If the interior temperature should rise too high, for
some reason, a thermal cutout switch will disconnect the
power and keep it disconnected until the temperature drops
to a safe value.
For proper air circulation, the bottom and side panels
must be in place. Be sure the bottom panel is installed
according to directions.
Power Requirements
A metal plate is attached to the back of your instrument
showing the input voltage for which the instrument was
originally wired. The regulated power supplies in the Type
180A will operate with line voltages from 105 to 125
volts at 117 nominal line volts, or from 210 to 250 volts at
234 nominal line volts. Proportionate line voltage variations
apply when other nominal line voltage primary connections
are made. For maximum dependability and long life the
voltage should be near the center of this range. Fig. 2-1
shows the connections for the various line voltages.
Voltages outside of these limits, or poor line-voltage
waveforms, may cause hum or jitter on the trace and may
cause unstable operation. Be sure to check for proper line
voltage if indications such as these are present.
2-1

Operating Instructions — Type 1 80A
Fig. 2-2 Primary connections for crystal-oven transformer, T702. The lower drawing indicates the position of the terminal strips.
Fan Connections
The fan is connected across a portion of the primary of
the power transformer and the connections need not be
disturbed when changing input line voltages.
Crystal Oven Transformer Connections
The crystal oven transformer has two primary windings
which are connected in series for 220 to 248 volt operation
as shown in Fig. 2-2.
Signal Output Connections
The time mark signals are connected to the MARKER
OUT connector by pushbutton switches. A banana jack
is mounted below each switch to provide an additional
output connector for each range. The signal appearing at
the banana jack is not affected by the operation of the
pushbutton for that range.
Keep in mind the type of service for which the time
marks are intended when making connections to the
MARKER OUT connector.
Table 1-1 in the Characteristics section of this manual
shows the output voltages and risetimes available. Type P93
Coaxial Cables are furnished with the Type 180A. If you
desire to get the optimum risetime from your instrument
you should use a 93 Q Terminating Resistor at the MARKER
OUT connector.
To disconnect a time marker from the MARKER OUT
connector, it is necessary to operate the CANCEL push
button switch. This will disconnect all of the time markers.
Then, you may reconnect the desired time markers to the
MARKER OUT connector by operating the appropriate
pushbuttons.
Sine-wave outputs of 5, 10 and 50 megacycles are
available at the MARKER OUT connector, and are selected
by pushbutton switches at the top of the front panel. Each
time you operate one of the sine-wave pushbutton switches,
it will cancel all of the output signals previously selected
and will over-ride any time mark pushbuttons that may be
depressed.
Triggering pulses are available separately from a con
nector on the front panel labeled TRIGGER OUT. Here,
too, the output signals are selected by the operation of a
pushbutton switch. However, pushing the switch for one
range will automatically cancel the range previously
selected, and, therefore, only one range of trigger pulses
is available at one time.
2-2

SECTION 3
CIRCUIT
DESCRIPTION
Block Diagram
In the Type 180A, time-marker and sine-wave outputs are
derived from a one-megacycle oscillator. The time-marker
signals are available individually at banana-jack connectors
or in combination at a coaxial connector. The sine-wave
signals are available individually at the coaxial connector.
In addition, a triggering signal is available at another
coaxial connector. The manner in which the circuits are
functionally arranged to achieve these ends is shown in
Figure 3-1.
The oscillator is an electron-coupled, crystal-controlled
oscillator. Its output signal is coupled to the 1-^tsec
Amplifier and Cathode Follower and to the Isolating CF.
To insure long-term stability, the crystal is housed in a
temperature-controlled oven.
In the 1-jU.sec Amp and CF stage, the sigpal is amplified
for coupling to the front-panel l-/xsec banana jack and
push-button switch. The output from this stage is also con
nected to the input of the 5-mc Multiplier.
In the 5-mc Multiplier, the 1-fisec time markers drive an
rf amplifier tuned to 5 megacycles. The resulting 5-mc sine-
wave output is coupled to the input of the 10-mc Multiplier,
which in turn, drives the 50-mc Multiplier. The 10-mc and
50-mc Multipliers, like the 5-mc Multiplier, are rf amplifiers
tuned to the desired output frequency. The sine-wave out
puts from all three multipliers are connected to the
associated pushbuttons. The pushbuttons are mechanically
linked so that only one of the sine-wave signals can be
selected at a time. The signal so selected is connected
through the pushbutton switches to the MARKER OUT
coaxial connector.
Fig. 3-1 Type 180A functional block diagram.
3-1

Circuit Description — Type 1 80A
The oscillator signal connected to the Isolating CF drives
the 5-jUsec Divider. In this circuit, one output pulse is
produced for every five input pulses. Since the input signal
consists of 1-microsecond pulses, one output pulse will
occur every 5 microseconds. The 5-p.sec markers are coupled
to the pushbutton switches and banana jacks for external
use, and are also connected to the input of the 10-micro
second divider. The 10-,u,sec divider produces one output
pulse for every two input pulses. Hence with 5-/xsec markers
at the input, the output markers will be spaced 10-micro-
seconds apart.
All of the other dividers are similar to the 5-fisec or 10-
/j.sec divider. They produce one output pulse for every
five or every two input pulses. In this manner, the original
1-microsecond time-marker signal is accurately "counted
down” to as low as 5 seconds.
The output signals from all of the dividers are connected
to an associated banana jack and pushbutton. The push
buttons are mechanically linked so that any number may
be depressed at one time. A cancel button (not shown in
Fig. 3-1) is provided to mechanically release all of the
depressed buttons.
The signals at the 10-/isec, 100-/tsec, 1-msec, 10-msec,
100-msec, and 1-sec banana jacks are also connected to
the TRIGGER RATE pushbuttons. Here, any one of the
signals may be selected for connection to the TRIGGER
OUT connector. The signals are coupled to the coaxial
connector through two cathode-followers.
OSCILLATOR AND AMPLIFIER
Oscillator
Circuit details for the oscillator appear on the OSCIL
LATOR AND MULTIPLIER schematic diagram. The oscillator,
V100B, operates as a conventional electron-coupled, crystal-
controlled oscillator. The crystal is contained in a tempera
ture-controlled oven. A front-panel lamp, B101, is connected
in parallel with the heating element to indicate operation
of the thermostat. A variable capacitor, C l 05, is connected
in parallel with the crystal to permit slight adjustments of
the crystal resonant frequency.
The output waveform at the plate of V100B is capaci-
tively coupled to the grid of the l-/j.sec Amplifier, V104B,
and direct coupled to the Isolating Cathode Follower,
V100A. The rc network, RI 03 -003 , increases the risetime of
the pulse at the grid of V104A (in comparison to the pulse
at the grid of V100A) to insure the coincidence of the 1-
and 5-^.sec markers.
l-/xsec Amplifier
The l-/j,sec Amplifier is a conventional voltage amplifier
with high-frequency peaking in the plate circuit. The gain of
the stage is about 2.5. The inductor, LI 07, serves to improve
the risetime of the output waveform.
l-/isec Output CF
The 1-jU.sec Output CF, V104A, is biased below cutoff
through divider R114-R115. This insures that only the fast
rising positive pulses reach the output. The network consisting
of Cl 16 and R116 differentiates the rectangular pulses
from the plate of V104B, causing sharp, positive-going
pulses to appear at the grid of V104A. These pulses
appear at the cathode of V104A as 1-^isec time markers.
From here, they are coupled to the output switching cir
cuits and to the 5-mc Multiplier.
SINE-WAVE MULTIPLIERS
5-Mc Multiplier
The 5-mc Multiplier, V124, is a conventional grid-leak
biased, Class-C amplifier, plate-tuned to 5 megacycles. The
exciting l-/xsec (1-megacycle) pulses cause the plate tank
circuit to resonate at 5 megacycles. The 5-mc sine-wave is
link-coupled from the output tank circuit and fed to the
output switch. Plate voltage for the stage is also controlled
by the output switch. The switching arrangement is such
that V I24 will operate only when the 5-, 10- or 50-mc
pushbutton is actuated.
10-MC Multiplier
V I34 acts as a frequency doubler. The primary and
secondary of the rf transformer in the plate circuit of
V I34 are both tuned to 10 me. The 10-mc output signal is
link-coupled to the output switch, and plate voltage for
the stage is also coupled through the output switch. The
switching arrangement is such that the stage operates only
when the 10- or 50-mc pushbutton is selected.
50-MC Multiplier
The 50-Mc Multiplier, V I44, operates as a frequency
quintupler. The primary and secondary of the transformer in
its plate circuit are tuned to 50 me. The plate voltage of
this stage is turned on only when the 50-mc pushbutton is
depressed.
TIME-MARKER DIVIDERS
Basic Multivibrator
There are 13 frequency dividers in the Type 180A, pro
ducing thirteen of the fourteen output time markers. (The
fourteenth time marker is the original time marker derived
from the one-megacycle oscillator output.) The operation
of all thirteen dividers is essentially the same. In general, a
divider consists of a bistable multivibrator, with diode
coupling for triggering pulses, and two cathode-follower out
put stages. The operation of the 5-,asec multivibrator is
described below. The circuit notation of Figure 3-2 is used
for simplification.
In the quiescent state, V2 is held in conduction by the
grid-clamping action of V4 and VI is blocked out of
conduction by the fixed grid bias. The plates of VI and V3
rest at about +225 volts. The cathode of V3 is normally
at about +225 volts in the absence of a triggering pulse.
The multivibrator is triggered into its unstable state by
a negative-going 50-volt pulse at the cathode of V3. The
pulse drives the cathode more negative than the plate, per-
3-2

Circuit Description — Type 1 80A
Fig. 3-2 Basic 5-fisec. multivibrator. Circuit numbers have been changed for simplification.
mitting the tube to conduct. As the tube conducts, the pulse
is coupled to the grid of V2 through capacitor C l. The
negative pulse breaks the clamping action of V4, driving
the grid of V2 negative and causing V2 cathode current
to decrease. The decreasing cathode current through R3
causes the cathode voltage of VI to drop also. As the
cathode voltage of VI approaches the fixed bias voltage,
VI starts to conduct, causing a further decrease in the
voltage at the plate. This negative-going voltage is coupled
to the grid of V2 through C l, reinforcing the switching
action.
The plate voltage of VI drops to approximately 175
volts. With the plate of V3 at 175 volts and the cathode at
225 volts, subsequent trigger pulses cannot reach the grid
of V2. As the charge on Cl equalizes, the grid voltage of
V2 becomes more positive until the clamping action of V4 is
restored and V2 begins to conduct. As V2 goes into con
duction, the resulting rise in cathode voltage causes VI
to cut off. As the plate voltage of VI rises, Cl is charged
through R2. In the absence of trigger pulses, this would
mark the return of the multivibrator to its stable state.
The values of R l, R2 and Cl have been selected to provide
a lapsed time of approximately 5 microseconds from the
time of triggering to the return to the stable state.
As the multivibrator returns to its stable state, the plate
of V3 becomes more positive than the cathode, permitting
the next trigger pulse to be coupled to the grid of V2.
Isolating CF
The 1-megacycle waveform at the plate of the oscillator,
V100B, is coupled to the 5-/tsec Divider through cathode
follower V100A. The function of the cathode follower is to
isolate the loading effects of the multivibrator triggering
circuit from the oscillator.
5 /xsec Divider
The operation of the 5 /xsec Multivibrator is described in
previous paragraphs. Referring to the OSCILLATOR and
MULTIPLIER diagram, the 5-/isec adjustment (R168) deter
mines the charging rate of C l 67, and hence the elapsed
time for one cycle of operation. LR171 in the plate circuit
of V165B improves the high-frequency response of the circuit
and thereby the leading edge of the output waveform.
The waveform at the plate of V165A is coupled to the
10-/j,sec Divider through the Isolating CF, V173B. The
purpose of this cathode follower is to prevent signals
generated in the 10-^.sec Divider from being coupled back
into the 5-/xsec divider.
The output waveform at the plate of V165B is differ
entiated by C l 77 and R177, and then coupled to the push
button circuits through the OUTPUT CF. Notice that the grid
of V173A is biased at —17 volts. Operating the stage in
this manner insures that only the fast-rising parts of the
multivibrator waveform are coupled to the output.
10 /xsec Divider
The circuit configuration and operation of the 10-/isec
Divider is essentially the same as the 5-/xsec Divider with
one exception. Instead of producing one output pulse for
every five input pulses, the 10-/xsec Divider produces one
3-3

Circuit Description — Type 1 80A
output pulse for every two input pulses. This is brought
about by the proper selection of circuit time constants.
Other Dividers
All of the dividers in the Type 1 80A perform in the same
manner as the 5-fisec or 10-,usec divider. In each divider,
time constants have been selected to provide the appro
priate duty cycle. Notice that the last divider, the 5-sec
Divider, does not have an Isolating CF. This, of course, is
because there is no need for a 5-p.sec triggering pulse.
EXTERNAL TRIGGERING
Switching
The manner in which all of the dividers and multiplier
output signals are connected to the output terminals is shown
on the TRIGGER CF & SW ITCHING diagram. Notice that
all of the divider Output CFs are connected directly to the
banana jacks. Switch connections to the MARKER OUT
connector are made through an isolating resistor.
To provide an external triggering signal, switching con
nections are made directly to the 10-/xsec, 100-,usec, 1-ms,
100-ms or 1-second banana jacks. These signals are
selected by a pushbutton switch in which only one
button may be locked in the depressed position. The
selected signal is fed to the input of the first TRIGGER CF,
and is available at the TRIGGER OUT terminal.
Trigger CFs
The output signal from the first cathode follower is
capacity coupled to the grid of the second CF. The dc level
of a time-marker signal coupled in this fashion is a function
of the signal repetition rate. To avoid wide excursions in
the output-signal dc level, a grid-clamping diode is included
in the grid circuit of V553B.
Under no-signal conditions, the diode and its associated
voltage divider, R560-R561, maintain the grid voltage at
approximately —8 volts. Upon the arrival of a positive-going
time-marker pulse, the diode ceases to conduct, permitting
the grid, and hence the cathode, to follow the signal
excursion. At the completion of the pulse, the diode again
clamps the grid at about — 8 volts. This is true regardless
of the pulse repetition rate.
With the grid of V553B always clamped at about —8
volts between pulses, the output pulses at the TRIGGER
OUT connector will always start at about 6.5 volts. Their
amplitude will depend upon the amplitude of the input
signal at the grid of V553A.
POWER SUPPLY
Transformers
Plate and filament power for the tubes in the Type 1 80A
is furnished by a single power transformer, T701. The
primary has two equal tapped windings; these may be
connected in parallel for 105- to 125-volt operation, or
in series for 210- to 250-volt operation. Silicon rectifiers
are employed for the three separate full-wave, bridge-
type, power supplies. The three supplies furnish regulated
dc voltages of —150 volts, +225 volts and +350 volts.
In addition, —8 volts bias is taken from the —150 volt
supply through a voltage divider, and —17 volts bias is
taken from the cathode of V433.
A separate transformer, T702, is provided to supply 6.3
volts for the crystal-oven heater. Notice that the primary
connections bypass the power switch. This arrangement
insures constant crystal-oven temperature even though the
power switch may be turned off.
A thermal cut-out is provided in the primary of T701 to
open the circuit should the Type 180A internal temperature
rise too high. The device is set to open at 137-degrees
Fahrenheit. If the cut-out opens, the crystal-oven will operate
but the fan and other circuits will not operate. Then, when
the internal temperature drops below 137-degrees, the
cutout will close, restoring power to the other circuits.
— 150 Volt Supply
Reference voltage for the —150-volt supply is established
by a gas diode Voltage-Reference Tube V749. This tube,
which has a constant voltage drop, establishes a fixed
potential of about —84 volts at the grid of V744B, one-half
of a Difference Amplifier. The grid potential for the other
half of the Difference Amplifier V744A, is obtained from
a voltage divider consisting of R742, R743, and R744. R743,
the —150 Adj. control, determines the percentage of total
voltage that appears at the grid of V744A and thus deter
mines the total voltage across the divider. When this
control is properly adjusted, the output voltage is exactly
—150 volts.
Should the loading on the supply tend to change the
output voltage, the potential at the grid of V744A will
change in proportion, and an error voltage will exist
between the two grids of the Difference Amplifier. The error
signal is amplified by V744B, whose plate is dc-coupled
to the grids of the Series Tubes V757 and V767. The error
voltage appearing at the grids of the Series Tubes will
change the voltage drop across the tubes and hence
change the voltage at the plates of the tubes. This change
in voltage at the plates of the Series Tubes, which will
be in a direction to compensate for the change in the
output voltage, is coupled through the rectifiers and C741
to the output and thus returns the output voltage back
to its established value of — 150 volts. C744 improves the
ac gain of the feedback loop, and thus increases the
response of the circuit to sudden changes in output voltage.
+ 225-Volt Supply
The —150-volt supply serves as a reference for the +225
volt supply. The voltage divider R736-R737 establishes a
voltage of essentially zero at the grid of the Amplifier
V724. (The actual voltage at this grid will be equal to the
bias voltage required by the tube.) If the loading should
tend to change the output voltage, an error voltage will
appear at the grid of the Amplifier. The error voltage will
be amplified and will appear at the grid of the Series
Tube V707A. The cathode of V707A will follow the grid,
and thus the output voltage will be returned to its estab
lished value of +225 volts. C736 improves the response of
the regulator circuit to sudden changes in output voltage.
3-4

Circuit Description — Type 1 80A
A small sample of the unregulated-bus ripple will appear
at the screen of V724 through R724. This ripple signal
appearing at the screen (which acts as an injector grid)
will produce a ripple component at the grid of V707A
which will be opposite in polarity to the ripple appearing
at the plate of V707A. This tends to cancel the ripple at
the cathode of V707A, and hence reduces the ripple on
the + 225-volt bus. This same circuit also improves the
regulation of the circuit in the presence of line-voltage
variation.
+ 350-Volt Supply
The +350-volt supply functions in the same manner as
the + 225-volt supply. Rectified voltage from terminals 9
and 16 of the power transformer is added to the voltage
supplying the + 225-volt regulator to supply power for the
+350-volt regulator.
Bias-Voltage Supply
The two bias supply voltages are drawn from separate
sources. The —17-volt supply is drawn from the cathode of
V433B. C770, connected between the -17-volt supply
and ground aids in filtering the output of the supply.
The — 8 volts supply is drawn from the R774-R776
divider which is connected across the output of the -15 0 -
volt supply.
Color Coding
The power supply circuits can be checked at any point
in the instrument by following the color coding of the
wires. This coding follows the standard RMA system.
Negative voltages from the supply are carried in wires
with a black base color while white wires are used for
positive voltages. For example, —150 is found on black
with a brown and a green tracer stripe while +225 will
be found on white with two red tracers. (The last figure is
not indicated). The +350 volts will be found on white with
an orange and a green tracer.
The bias voltages do not follow the coding system,
however. The —8 volt bias will be found on white with a
black tracer, and —17 volts will be found on white with
grey tracer.
3-5

NOTES

SECTION 4
MAINTENANCE
PREVENTIVE MAINTENANCE
Air Filter
Care must be taken to assure free ventilation of the Type
180A inasmuch as some of the components are operated at
dissipation levels such that excessive interior temperatures
will result without adequate air circulation. To assure free
passage of air the instrument must be placed so the air
intake is not blocked, and the filter must be kept clean.
Moreover, the side panels and bottom cover must be in
place for proper air circulation; do not remove the covers
except during maintenance.
A washable “ E-Z KLEEN" filter is used at the air intake
port of the instrument. Under normal operating conditions
the filter should be inspected, and cleaned if necessary,
every three to four months. More frequent inspection is
required when the operating conditions are more severe.
Th following cleaning instructions are issued by the
filter manufacturer:
1. If grease or dirt load is light, remove filter from installa
tion and rap gently on hard surface to remove loose dirt.
Flush remaining dirt or grease out of filter with a stream
of hot water or steam; flush from clean side.
2. If load is too heavy for treatment described in (1), pre
pare mild soap or detergent solution in pan or sink deep
enough to cover filter when laid flat. Agitate filter up and
down in solution until grease or dirt is loosened and
floated off.
3. Rinse filter and let dry.
4. Dip or spray filter with fresh Filter Coat or Handi-
Coater. These products are available from the local repre
sentative of the Research Products Corporation, and from
most air-conditioner suppliers.
Recalibration
The type 180A is a stable instrument and will provide
many hours of trouble-free operation. To insure the
reliability of measurements obtained on the Type 180A we
suggest that its calibration be checked after each 500
hours of operation, or at least every six months if used
intermittently. A check of the calibration also provides a
means for checking the operation of each circuit. Minor
operational deficiencies that are not apparent in normal
use are often detected during a calibration check.
Visual Inspection
You should visually inspect the entire instrument every
few months for possible circuit defects. These defects may
include such things as loose or broken connections, damaged
binding posts, improperly seated tubes, scorched wires or
resistors, missing tube shields, or broken terminal strips.
For most visual troubles the remedy is apparent; however
particular care must be taken when heat-damaged com
ponents are detected. Overheating of parts is often the
result of other, less apparent, defects in the circuit. It is
essential that you determine the cause of overheating
before replacing heat-damaged parts in order to prevent
further damage.
Fan Motor
The fan motor bearings are permanently lubricated and
need not be oiled. The fan blade should be cleaned each
time the filter is cleaned.
Soldering and Ceramic Strips
Many of the components in your Tektronix instruments
are mounted on ceramic terminal strips. The notches in
these strips are lined with a silver alloy. Repeated use of
excessive heat, or use of ordinary tin-lead solder will
break down the silver-to-ceramic bond. Occasional use of
tin-lead solder will not break the bond if excessive heat is
not applied.
Fig. 4-1. Soldering iron tip properly shaped and tinned.
4-1

Maintenance — Type 180A
If you are responsible for the maintenance of a large
number of Tektronix instruments, or if you contemplate
frequent parts changes, we recommend that you keep on
hand a stock of solder containing about 3% silver. This
type of solder is used frequently in printed circuitry and
should be readily available from radio-supply houses. If
you prefer, you can order the solder directly from Tektronix
in one pound rolls. Order by Tektronix part number 251-514.
Because of the shape of the terminals on the ceramic
strips it is advisable to use a wedge-shaped tip on your
soldering iron when you are installing or removing parts
from the strips. Fig 4-1 will show you the correct shape
for the tip of the soldering iron. Be sure to file smooth all
surfaces of the iron which will be tinned. This prevents
solder from building up on rough spots where it will
quickly oxidize.
When removing or replacing components mounted on
the ceramic strips you will find that satisfactory results are
obtained if you proceed in the manner outlined below.
1. Use a soldering iron of about 75-watt rating.
2. Prepare the tip of the iron as shown in Fig. 4-1
3. Tin only the first 1/16 to V8 inch of the tip. For
soldering to ceramic terminal strips tin the iron with
solder containing about 3% silver.
in-rwuM —
- ----
Fig. 4-2. Correct method of applying heat in soldering to a ceramic
strip.
4. Apply one corner of the tip to the notch where you
wish to solder (see Fig. 4-2).
5. Apply only enough heat to make the solder flow
freely.
6. Do not attempt to fill the notch on the strip with
solder; instead, apply only enough solder to cover
the wires adequately, and to form a slight fillet on
the wire as shown in Fig. 4-3.
In soldering to metal terminals (for example, pins on a
tube socket) a slightly different technique should be em
ployed. Prepare the iron as outlined above, but tin with
ordinary tin-lead solder. Apply the iron to the part to be
soldered as shown in Fig. 4-4. Use only enough heat to
allow the solder to flow freely along the wire so that a
slight fillet will be formed as shown in Fig.4-3.
Fig. 4-3. A slight fillet of solder is formed around the wire when
heat is applied correctly.
General Soldering Considerations
When replacing wires in terminal slots clip the ends
neatly as close to the solder joint as possible. In clipping
the ends of wires take care the end remove does not fly
across the room as it is clipped.
Occasionally you will wish to hold a bare wire in place
as it is being soldered. A handy device for this purpose is
a short length of wooden dowel, with one end shaped as
shown in Fig. 4-5. In soldering to terminal pins mounted
in plastic rods it is necessary to use some form of "heat
sink" to avoid melting the plastic. A pair of long-nosed
pliers (see Fig. 4-6) makes a convenient tool for this
purpose.
Fig. 4-4. Soldering to a terminal. Note the slight fillet of solder—
exaggerated for clarity— formed around the wire.
Ceramic Strips
Two distinct types of ceramic strips have been used in
Tektronix instruments. The earlier type mounted on the
chassis by means of #2-56 bolts and nuts. The later type
is mounted with snap-in, plastic fittings. Both styles are
shown in Fig. 4-7.
4-2

Maintenance — Type 1 80A
To replace ceramic strips which bolt to the chassis, screw
a #2-56 nut onto each mounting bolt, positioning the bolt
so that the distance between the bottom of the bolt and
the bottom of the ceramic strip equals the height at which
you wish to mount the strip above the chassis. Secure the
nuts to the bolts with a drop of red glyptal. Insert the
bolts through the holes in the chassis where the original
strip was mounted, placing a # 2 star washer between
each nut and the chassis. Place a second set of # 2 flat
washers on the protruding ends of the bolts, and fasten
them firmly with another set of # 2-56 nuts. Place a drop
of red glyptal over each of the second set of nuts after
tightening.
Fig. 4-5. A soldering aid constructed from a V4 inch wooden
dowel.
Mounting Later Ceramic Strips
To replace strips which mount with snap-in plastic
fittings, first remove the original fittings from the chassis.
Assemble the mounting post on the ceramic strip. Insert
the nylon collar into the mounting holes in the chassis.
Carefully force the mounting post into the nylon collars.
Snip off the portion of the mounting post which protrudes
below the nylon collar on the reverse side of the chassis.
NOTE
Considerable force may be necessary to push the
mounting rods into the nylon collars. Be sure
that you app ly this force to that area of the
ceramic strip above the mounting rods.
Cleaning Ceramic Strips
After soldering is completed on ceramic strips, all rosin
and other residue should be removed, using Trichloro
ethylene, Fotocol or other residue-free solvent, applied with
a swab or brush.
REPLACEMENT PARTS
Standard Parts
Replacement components can be obtained from Tek
tronix at current net prices. However, since most of the
Fig. 4-6. Soldering to a terminal mounted in plastic.. Note The
use of the long-nosed pliers between the iron and thhe coil form
to absorb the heat.
components are standard electronic and radio parts, they
can generally be obtained locally in less time than required
to obtain them from the factory. Before ordering or pur
chasing parts, be sure to consult the parts list to determine
the tolerances required.
Tektronix-Manufactured Parts
Tektronix manufactures almost all of the mechanical
parts, and some of the electronic components, used in
your instrument. When ordering mechanical parts, be sure
to describe the part completely to prevent delays in filling
your order.
The Tektronix-manufactured electronic components are
so noted in the parts list. These components, as well as
the mechanical parts, must be obtained from the factory or
from the local Tektronix Field Engineering Office.
Replacement information notes sometimes accompany
the improved component to aid in its installation.
Each part in your instrument has a 6-digit Tektronix part
number. This number, together with a description of the
part, will be found in the parts list. When ordering parts,
be sure to include both the description of the part and the
part number. For example, a certain resistor should be
ordered as follows: R110, 220K, ’/2W , Fixed, Comp., 10%,
part number 304-224, for a Type 180A Time-Mark Gen
erator, Serial Number
-------- . When parts are ordered in
this manner we are able to fill your order promptly, and
delays that might result from transposed numbers in the
part number are avoided.
NOTE
Alw a ys include the instrument TYPE and SERIAL
NUMBER in any correspondence concerning your
instrument.
TROUBLESHOOTING AND CIRCUIT ISOLATION
General Information
The following sections contain information necessary for
troubleshooting in the Type 180A. Although the Type 180A
4-3

Maintenance — Type 1 80A
Fig. 4-7. Two types of ceramic strip mountings.
is a complex instrument it can conveniently be divided
into basic sections. This division is shown on the Block
Diagram of the instrument. The sections that follow describe
a method of isolating the trouble to a basic circuit, and
then locating the trouble within the basic circuit.
Power Supply
Before attempting to locate a particular trouble in any
circuit the power supply should be checked. Proper opera
tion of every circuit within the Type 180A is dependent
upon the proper operation of the regulated power supply.
Failure of the power supply to regulate properly may
appear as an apparent trouble at some other point in
the instrument.
If your Type 1 80A appears to be completely inoperative,
make sure that it is properly connected to a source of
power. If the pilot lamp on the front panel, and the fan
at the rear of the instrument, do not come on when the
power switch is turned on, check the source of power, the
power cord connection, and the fuse.
If the power supply is receiving the power line voltage
correctly, the outputs of the various supplies should be
checked next. The power supply outputs can be checked at
the points shown in Fig. 5-2. If an improper voltage reading
is found, the first thing to suspect is the tubes. Replace all
the tubes in the suspected circuit with new tubes. If this
cures the trouble, replace the old tubes, one at a time,
until the defective tube is found.
If replacing the tubes does not cure the trouble, check
the components through which the tube draws current.
Shorted tubes sometimes draw enough current to overload
plate-load resistors and cathode resistors. Frequently, a
visual inspection of the circuit will reveal burned or dis
colored parts.
Circuit Isolation
Before attempting to isolate a trouble in either the
oscillator or divider circuits, check the operation of the
power supply as described in the preceding section.
Removal of V I62 from its socket, isolates the oscillator and
multiplier stages from the divider stages. After removing
V I62 from its socket use an oscilloscope to check the output
at the 1-microsecond banana jack. If one megacycle output
is available at the front panel you may assume that the
oscillator stage is operating correctly.
Oscillator
If one megacycle output is not available at the front
panel, the oscilloscope should be used to trace back
through the amplifier stage, V104A, to the crystal oscillator,
V100B. If the oscillator waveform appears at the plate of
V100B, it should also appear at the cathode of V100A.
If you find that the oscillator waveform appears at the
cathode of V100A all the circuits are working properly
up to that point.
Failure to discover the oscillator waveform at any point
indicates trouble in the preceding circuitry. Replacement
of tubes should be tried first. If tube replacement does
not cure the trouble, the schematic diagram of the circuit
should be used as a guide to troubleshooting with a
voltmeter.
Dividers
If operation of the oscillator and amplifier is found to
be satisfactory, replace V I62, and proceed to check the
divider stages until you have found the last working
stage. The procedure given in Step 3 of the Calibration
Procedure can be used to check the operation of the divider
stages. Remove the Input Diode which couples the output
of the defective stage to the following stages and see if
normal operation of the defective stage is resumed. If it
is, the trouble is probably due to loading by the following
stages, and the trouble should be looked for there.
Replace all the tubes in the defective circuit. If this cures
the trouble replace the old tubes, one at a time, until the
defective tube is found.
If the trouble does not appear to be due to tubes, use
the test oscilloscope to check for triggering signal to the
multivibrator. If this is correct, check the output of the
multivibrator at the plate of the output triode. If output
is present here, check the grid of the cathode follower
output stage. If the output signal is found at the grid,
proceed to check the cathode. If a loss of signal is noted
at the cathode, and if you have tried several tubes with
no improvement, the signal path through the switch to
the MARKER OUT connector should be checked.
If no output is found at the plate of the multivibrator,
and if the signal pulse is being provided correctly, measure
the plate voltages at both plates of the multivibrator. The
4-4

Maintenance — Type 1 80A
voltage at the left-hand plate should be equal to the supply
voltage (+225 volts). The voltage at the right-hand plate
should be down by a considerable amount, possibly as
low as +100 volts.
If the plate voltage proves to be correct, measure
bias voltage being applied to the grid of the left-hand
triode of the multivibrator. This voltage should be between
five and seven volts negative.
If these measures fail to locate the trouble in the circuit,
a check of the various circuit components is indicated.
Frequency Multipliers
Little difficulty beyond that caused by tubes will normally
be found with the multipliers. The Calibration Procedure
provides the instructions for adjusting the output of three
multiplier stages.
4-5

NOTES