Tektronix 315D Series User manual

CATHODE-RAY OSCILLOSCOPE
TYPE 315D
SERIAL N U M B E R _______________
INSTRUCTION
MANUAL
MANUFACTURERS OF CATHODE-RAY AND VIDEO TEST INSTRUMENTS
Sunset Highway an Barnes Roa • P. O. Box 831 • Portlan 7, Oregon, U. S. A.
Phone: CYpress 2-2611 • Cables: Tektronix

SECTION I Time Base Magnifier
General Descr pt on
The TEKTRONIX Type 315D catho e-ray oscil
loscope is a small compact an portable high-perform
ance laboratory instrument particularly esigne to
occupy minimum space. The vertical ban wi th ex
ten s to five megacycles from c. Time-base ranges
exten ing from one microsecon per sweep to fifty
cycles per sweep are provi e . An amplitu e cali
brator an a time-base magnifier are also inclu e .
Sensitivity
Twelve calibrate fixe sensitivities: ac only, 0.01,
0.02 an 0.0& volts per ivision, 5 cycles to 5 mega
cycles : c an ac 0.1, 0.2, 0.5,1, 2, 5,10, 20, an 50 volts
per ivision. These sensitivities fit graticule ivisions
for irect rea ing of voltages. Continuously variable
10 to 1 sensitivity multiplier control also available.
Calibrator
Square wave at approximately one kilocycle avail
able at front-panel UHF connector at four fixe peak-
to-peak voltages of 0.1, 1, 10, an 100 volts with accu
racy within 3 per cent.
Signal Delay
Quarter-microsecon signal elay line permits all
of the triggering waveform to be viewe .
Trigger Amplitude Discriminator
Permits time base to be triggere at any esire
amulitu e point on the triggering waveform.
Time Base
Twenty-four fixe times per ivision between
0.1 microsecon an 5 secon s per ivision fit grati
cule ivisions for irect rea ing of time. Continuously
variable 10 to 1 sweep-time control also available.
Magnifies time base to right an left of center by
factor of five times. Portion of trace appearing at cen
ter is ma e five times as wi e.
Direct-Coupled Unblan ing
Accommo ates slowest sweeps.
Cathode-Ray Tube
Flat-face high efinition three-inch tube.
Graticule
Quarter-inch ivisions, 8 lines vertically, 10 lines
horizontally. Variable-intensity e ge lighting.
Power Supply
Four electronically regulate plate-voltage supplies.
Power transformer will operate on either 117 or 234
volts, 50 to 800 cycles. (Special ventilating fan re
quire for other than 50- to 60-cycle operation.)
Crt Accelerating Voltage
1630 volts from electronically regulate rf oscillator
high-voltage supply.
Ventilating Fan
The Type 315D is normally supplie with a
50- to 60-cycle in uction-motor fan. For frequencies
much above 60 cycles a c commutator motor an
selenium rectifier are available at extra cost to exten
the range to 800 cycles.
Dimensions
12^s" high, 8$4" wi e an I8V4" long.
Weight
36 lbs.
Construction
Wel e aluminum alloy.
Finish
Ano ize photo-etche aluminum panel, grey
crackle enamel case.
SECTION I, PAGE 1 TYPE 315D

Funct ons of Front-Panel Term nals
and Controls 5X MAGNIFIER
(Re label,
re knob)
Vertical Amplifier
MULTIPLIER Four-position switch to multiply
VOLTS/DIVISION by factors
of 1, 2, or 5. Fourth position
marke 10-1 in re permits re
coaxial knob to a just multiplier
continuously over 10 to 1 range.
INPUT Coaxial UHF connector for con
necting signal to vertical- eflec
tion system.
AMPLITUDE Seven - position control provi es
four fixe ac sensitivities an three
fixe c sensitivities.
FOCUS A justs voltage of focusing ano e
to provi e focusing.
INTENSITY A justs control-gri voltage to
control brightness of trace.
SCALE ILLUM A justable series resistor in grati
cule lighting circuit to control
amount of scale illumination.
POSITION
HORIZ. A justs average voltage of hori
zontal eflection plates to position
trace horizontally.
VERT. A justs average voltage of verti
cal eflection plates to position
trace vertically.
TIME BASE Four-position switch to multiply
MULTIPLIER time-base TIME/DIVISION by
factors of 1, 2, or 5. Fourth posi
tion marke 10-1 in re permits
re coaxial knob to a just multi
plier continuously over 10 to 1
range.
RANGE Eight - position switch provi es
eight fixe time base times per i
vision in eca e ratio between
0.1 microsecon per ivision to
1 secon per ivision.
CALIBRATOR
TRIGGER
SELECTOR
STABILITY
(Re label,
re knob)
TRIGGER
AMPLITUDE
DISCRIMI
NATOR
POWER ON
CAL OUT
EXT TRIGGER
AC Bin ing
Post
DC Bin ing
Post
-(-GATE
SAWTOOTH
GND
Two-position switch turns time-
base magnifier on in clockwise po
sition, returns time base to normal
in counterclockwise position.
Five-position switch selects four
fixe peak-to-peak squarewave
voltages of 0.1, 1, 10, or 100 volts.
Turns calibrator oscillator off in
fifth position.
Ten-position switch selects trigger
source an accommo ates trigger
circuits to rising or falling trigger
waveforms. Accommo ates trig
ger circuits to fast-rising or slow-
rising triggering waveforms.
A justs voltages of gating multi
vibrator so that it can be set for
recurrent operation or at the
threshol of recurrent operation
for triggere sweeps.
Continuously variable voltage con
trol etermines point of operation
of trigger-inverter stage to select
point on triggering waveform at
which time-base circuit is trippe .
AC supply off-on toggle switch.
Coaxial UHF connector for output
of calibrator oscillator.
Connects to EXT. positions of
TRIGGER SELECTOR switch
through capacitor.
Connects irectly to EXT. posi
tions of TRIGGER SELECTOR
switch.
Bin ing post provi es 25-volt posi
tive gating pulse coinci ent with
time base.
Bin ing post provi es positive
going sawtooth voltage coinci ent
with time base.
Bin ing post connecte to frame
of instrument.
TYPE 315D SECTION I, PAGE 2

SECTION II
Operat ng Instruct ons
The TEKTRONIX Type 315 Oscilloscope may be
operate in any in oor location or in the open if it is
protecte from moisture.
Ventilation
Force -air cooling is require so that care must be
taken to avoi obstructing the air intake to the cir
culating fan.
WARNING: The Type 315D Oscilloscope
shoul not be operate unless the fan is run
ning. The interior will reach angerous tem
peratures within five to ten minutes of such
operation.
The operation of the calibrator an the trigger cir
cuits of the Type 315 oscilloscope is enough ifferent
that it is especially important for users familiar with
previous TEKTRONIX oscilloscopes to un erstan
the ifference.
The vertical amplifier is sufficiently stable that once
the gain has been stan ar ize , voltages can be rea
irectly from the graticule just as you woul rea a
voltmeter. For this reason, the calibrator in the
Type 315 is not continuously variable in amplitu e as
are the calibrators in previous TEKTRONIX oscil
loscopes. The calibrator is inten e to be use as a
source of squarewave voltage, operating in the vi
cinity of one kilocycle, available at four accurate fixe
voltage levels, 0.1, 1, 10, an 100 volts, peak to peak.
It is useful to supply a signal for aligning the vertical
amplifier, an the attenuator an probe, as well as for
stan ar izing the gain of the vertical amplifier to the
graticule calibrations.
To check the calibration of the vertical amplifier,
make a connection between the CAL OUT terminal
an the INPUT terminal. Then, for example, set the
VERTICAL AMPLIFIER MULTIPLIER selector
to 2, the AMPLITUDE selector to DC, 0.1, an the
CALIBRATOR to 1 volt, peak to peak. With these
settings, there shoul be exactly five graticule ivi
sions eflection of the trace. The amplifier gain can
be correcte for any ifference by means of a screw
river a justment in the center of the AMPLITUDE
selector switch.
To use the Type 315 for making an amplitu e
measurement, place the AMPLITUDE selector in the
approximate range of sensitivity esire , an the
MULTIPLIER selector on any one of the three steps,
1, 2, or 5. Each ivision of the graticule then cor
respon s to a voltage which can be etermine irectly
by multiplying the AMPLITUDE an the MULTI
PLIER scale rea ings.
In the most counter-clockwise position of the
MULTIPLIER selector, a continuously-variable gain
is provi e over a range of 10 to 1, marke in re . In
this selector position, varying the re knob mounte.
coaxially with the AMPLITUDE selector knob varies
the gain over the 10 to 1 range.
In a ition to the coaxial re knob on the AMPLI
TUDE selector switch, there are three other re knobs
mounte in a like manner on the TIME BASE an
TRIGGER controls. In each case, a re scale on the
panel pertains to the position or to the function of
the re knob.
In the operation of the time base of the Type 315
oscilloscope, the TRIGGER AMPLITUDE DIS
CRIMINATOR control is likely to be somewhat con
fusing to users familiar with previous TEKTRONIX
instruments. This control is not in any sense a trigger
amplitu e a justment. The triggering circuit is irect
couple to the vertical amplifier in the INT positions
of the TRIGGER SELECTOR switch, both for the
AC an DC connections of the vertical amplifier an
is irect couple to one of the EXT TRIGGER panel
connectors. The TRIGGER AMPLITUDE DIS
CRIMINATOR control etermines by amplitu e the
portion of the triggering waveform at which trigger
ing occurs. At settings of the DISCRIMINATOR
control near zero, triggering will occur at a point on
the waveform near zero. If the zero signal trace is
centere on the screen, triggering will occur at a point
on the trace above the center of the screen. Regar less
of the amplitu e of the waveform, triggering will
occur at a point on the trace the same istance above
the center of the screen, provi e that the wave
reaches that amplitu e. The negative trigger positions
of the TRIGGER SELECTOR control refer to the
irection of slope of the triggering waveform at which
triggering occurs. For example, to trigger the sweep
from a sine wave at a point beyon the peak but above
zero, the TRIGGER SELECTOR shoul be place
in one of the negative trigger positions an the TRIG
GER AMPLITUDE DISCRIMINATOR shoul be
turne to a positive position.
For slow rise signals whose rise time is longer than
SECTION II, PAGE 1 TYPE 315D

one microsecon , the TRIGGER SELECTOR shoul
be place in one of the SLOW RISE positions of the
scale. In these positions of the control, a regenera
tive trigger generator pro uces sharp triggers suitable
for initiating the sweep regar less of the rise time of
the input wave. For the FAST RISE positions, the
trigger generator is not regenerative an is capable
of pro ucing faster triggers so that for high frequency
or fast rise time signals, the TRIGGER SELECTOR
switch shoul be in one of these positions. The best
way to etermine which position is proper for a mar
ginal type of signal is to try both positions. There is
appreciable overlap.
Generally speaking, there is no ifference in trigger
sensitivity in the ifferent control positions. A change
in voltage which will pro uce a quarter of a ivision
eflection, will easily initiate a trigger at any spee
or in any part of the wave. For a small amplitu e
wave, the TRIGGER DISCRIMINATOR control will
nee to be set near zero. With settings near maximum
either clockwise or counterclockwise, a large trace will
be require to initiate a sweep an the point of initia
tion will be near the top or bottom of the waveform.
Calibrations on the DISCRIMINATOR ial are
approximately in volts for externally connecte trig
ger voltages. For internally erive triggers, approxi
mately seven ivisions on the DISCRIMINATOR
scale correspon s to about ten graticule ivisions of
eflection.
The magnifier circuit expan s to right an left the
portion of the trace that is centere on the screen.
Horizontal positioning prece es the magnifier circuits
so that this control is use for both the normal an
magnifie trace.
Placing the Type 315D Oscilloscope in Operation
for the First Time
The following proce ure is suggeste when you
put the instrument into service for the first time:
1. Set the panel controls as follows:
POWER OFF
VERTICAL AMPLIFIER MULTIPLIER. .2
VERTICAL AMPLIFIER
AMPLITUDE.DC, 0.1 VOLTS/DIVISION
FOCUS ...............................................CENTER
INTENSITY ....... COUNTERCLOCKWISE
SCALE ILLUM..................................CENTER
HORIZ. POSITION .......................... CENTER
VERT. POSITION ............................ CENTER
TIME BASE MULTIPLIER .......................... 1
TIME BASE RANGE................1 MILLISEC.
CALIBRATOR ..................................... 1 VOLT
TRIGGER SELECTOR.SLOW RISE, +INT.
STABILITY ......... COUNTERCLOCKWISE
TRIGGER AMPLITUDE
DISCRIMINATOR ................................ —50
2. Connect the power cor to a source of ac power
capable of supplying 4 amperes at 117 volts at
60 cps. (240 volts if power transformer is so con
necte , an 50 to 800 cps for the universal-fre
quency mo el.)
3. Make a connection between the CAL OUT
terminal an the INPUT terminal. Turn the
POWER switch to ON, an permit the instru
ment to warm up for about a minute.
4. A vance the INTENSITY control clockwise a
little past center.
5. A vance the STABILITY control until a trace
appears on the screen.
6. A just the FOCUS an INTENSITY controls
for a sharp trace an satisfactory brightness.
7. A just the two POSITION controls until the
trace is centere on the screen as esire .
8. Return the STABILITY control clockwise until
the trace just isappears an return the TRIG
GER AMPLITUDE DISCRIMINATOR con
trol clockwise towar O until the calibrator
waveform appears on the screen.
The stability control etermines whether the multi
vibrator retriggers itself or whether it returns to a
stable con ition after executing a single sweep for
each trigger receive .
In the SLOW RISE positions of the TRIGGER
SELECTOR switch the regenerative trigger gener
ator pro uces triggers of the same amplitu e when
trippe regar less of the amplitu e or spee of the
triggering waveform. The STABILITY control
shoul therefore be set at such a level that a trigger
output of this amplitu e will trigger the sweep an
thereafter no change in the STABILITY control set
ting will be nee e . The trigger sensitivity is the volt
age ifference nee e to trip the regenerative trigger
TYPE 315D SECTION II, PAGE 2

generator, which is etermine by the gain between
halves of this generator. There is no front-panel con
trol of this gain, but there is an internal screw river
a justment which shoul not be change , however,
except possibly after replacing the generator tube.
In the FAST RISE positions of the TRIGGER
SELECTOR switch regeneration between the halves
of the trigger-generator tube is effectively remove
by shorting out the plate-loa resistor of the input
pento e section. Since the circuit thus becomes a
catho e-couple amplifier, the amplitu e of the out
put triggers is epen ent on the ifferentiate rise 01
the triggering waveform. For slow-rising waveforms,
therefore, the output trigger will be too small to trip
the time-base generator. The point of transition at
which better triggering will result from one or the
other of the switch positions is not critical. For rise-
times near one microsecon it will be well to try both
types of operation. Triggering from the calibrator
waveform will be more satisfactory with the TRIG
GER SELECTOR switch in the SLOW RISE
positions.
®SECTION II, PAGE 3 TYPE 315D

SECTION III
C rcu t Descr pt on
Sweep Circuit
The time base of the TYPE 315 CATHODE-RAY
OSCILLOSCOPE is generate by means of a Miller
runup generator. New circuitry eliminates the usual
istortion of the early part of the sawtooth. A con
stant current charging source to the timing capacitor
improves the sawtooth linearity.
The triggering signal is selecte by means of the
TRIGGER SELECTOR switch connecte to the B
section of a catho e-couple phase inverter, V201,
with a gain of about six at each plate. The A section
gri is connecte to the arm if a potentiometer so that
its bias can be varie over a wi e range. By a justing
the bias properly you can select the portion of the trig
gering wave form that triggers the sweep.
A secon section of the trigger selector switch con
nects the output of B section plate to the trigger gen
erator, V202, for negative-going triggering waveforms
an the A section plate for positive-going triggering
waveforms.
The trigger generator consists of V202, as a bistable
multivibrator for slow-risetime trigger signals, an
as a catho e-couple amplifier for fast-risetime trig
ger signals. For signals with a risetime slower than
one microsecon , the multivibrator circuit will pro
vi e the best trigger signal. In the SLOW RISE posi
tions of the TRIGGER SELECTOR switch, SW201,
C227 connecte between the trio e-section gri an
pento e-section plate of V202 provi es the regenera
tion. For faster rising trigger signals, the FAST RISE
positions of.th'e switch effectively removes the regen
eration by shorting out plate-loa resistor R220 in the
pento e section of V202. V202 thus becomes a catho e-
couple amplifier.
Trigger output voltage is taken from the plate of
the trio e section of V202. The plate loa is in uctor-
resistor ifferentiating circuit, L221, R221, so that a
reasonably fast transition is require to evelope large
enough triggers to' operate the sweep circuit. The
multivibrator performs this fast transition for trig
gering waves otherwise too flat. It will perform a
regenerative transition in either irection for the slow
est risetime signals.
The sharp trigger signal is capacitance couple into
V203, a catho e-couple stage whose output is irect
couple through catho e follower V204A to the junc
tion of the plate of V211A an the catho e of V211B
of the casco e Eccles-Jor an multivibrator. A posi
tive signal on the B section gri of V203 is require
to trigger the multivibrator. The B section of V203
is also connecte to a bias-control potentiometer calle
STABILITY which sets the c level.
V204B, an V205 A an B surroun ing V204A com
prise a hol -off circuit. The function of the hol -off
circuit is to re uce the voltage on the gri of the trig
gering catho e follower, V204A, uring the sweep ana
for a short perio after the multivibrator has recov
ere . V205B performs this function. During the
sweep, V205B con ucts so that its plate rops. At
the termination of the sweep, V205B is cut off an
its plate rises towar 225 volts positive. A switche
capacitor between plate an groun elays this rise
towar +225 volts uring the charge perio , epen 
ing on the size of the capacitor. When the plate of
V205B reaches 100 volts positive it is clampe to this
voltage by io e-connecte V205A. The trigger am
plifier is so esigne that it will trigger the multivi
brator only when its plate is in the vicinity of 100 volts,
so that triggering is hel off uring the rise perio of
the plate of V205B.
V211 an V212 comprise the casco e Eccles-Jor an
multivibrator. The left-han si e of this multivibrator,
V211 A an B are normally con ucting. Triggering
is accomplishe with a positive trigger through V203
to catho e follower V204A causes it to ivert current
from the upper half of V211, so that the plate rises.
The positive step at V211B plate is couple through
catho e follower V210B to the gri of the opposite
lower si e of the multivibrator, V212B, an the multi
vibrator flops over with con uction on the right-han
si e. Catho e follower V210B acts as a buffer between
the plate of V21 IB an all other external loa s so that
the only a itional capacitance is that a e by the
input capacitance of the catho e follower. This per
mits the plate to execute a much more rapi rise. The
catho e follower rives the opposite si e of the multi
vibrator, the unblanking catho e follower, the hol -off
tube, V205B, an the gate output catho e follower,
V214A.
The sweep is gate by the negative-going portion
of the multivibrator, V212A an B. The plate of
V212A is connecte to the gri of the catho e-follower-
connecte pento e section of V214 through a spee -up
capacitor. The catho e of this catho e follower hol s
SECTION III, PAGE 1 TYPE 315D

the gri of V220 at about —3 volts through io e V21S
uring the quiescent state of the multivibrator. The
negative step from the multivibrator cuts off the
catho e follower an the catho e falls, isconnecting
the gri of V220 through io e V215. V220 is the
Miller tube time base generator. When the gri is
free from V214B catho e, it imme iately begins to
rop an the plate begins to rise. The plate of V220 is
couple back to the gri through catho e follower
V212A an the timing capacitor, an a Miller run up
commences. When the plate has risen to the vicinity
of 200 volts, the gri of catho e follower V213B has
risen to about 100 volts so that current begins to flow
in this tube which iverts current from the upper right
Section of the multivibrator, V212A, an the multivi
brator reverts to the initial stage with the left-han
si e con ucting. When V212A plate rises, it carries
the gri of V214B with it causing io e V215B to
con uct an the Miller gri to rise to —3 volts so
that the plate rops again to the starting position.
The a itional circuitry aroun the Miller tube an
irect-couple Eccles-Jor an multivibrator is pro
vi e to raise the maximum sweep spee an to elimi
nate the usual istortion of the sawtooth at the begin
ning of the Miller run-up action.
Since the multivibrator has no timing-circuit com
ponents, its recovery time of about 1 microsecon is
epen ent largely on tube an wiring capacitance,
an is therefore more or less constant over the entire
range of time bases. For the longer time bases, as
much as a millisecon is require to ischarge the
timing capacitor, so that circuitry is nee e to prevent
the multivibrator from being triggere before the Mil
ler tube has returne to its quiescent state. The re
quire hol -off function is pro uce by lowering the
plate return voltage of the trigger amplifier V203A
for an a equate perio after the time base termination.
Furthermore, a sharp ifferentiate pulse must be e
rive from a triggering waveform to trigger the multi
vibrator so as to prevent the multivibrator from re
triggering after the hol -off circuit has reache qui
escence, in the presence of a sustaine triggering
waveform.
The circuit complication aroun the Miller tube re
moves the step from the start of the Miller run up.
This is accomplishe by means of a c fee back net
work from the plate of the Miller tube back to its gri ,
which causes an equilibrium point to be establishe
where the plate of the Miller tube is resting at about
50 volts positive whenever the gri of the gating
catho e follower, V214B, is hel in a positive irection
by the right-han multivibrator, an the gri is at
—3 volts. This is well within the class A region of the
Miller tube, V220, where the plate voltage is irectly
proportional to the gri voltage. The relationship of
50 volts plate to —3 volts gri voltage is therefore
etermine by the gri to plate relationship of the
Miller tube itself in the class A region of its operation.
The actual gri voltage set by the voltage- ivi er
catho e follower arrangement with V214B through
isconnecting io e V215B an constant-current tube
V213A, etermines the starting voltage of the saw
tooth. When io e V215 B isconnects the Miller tube
gri from the ivi er constant-current tube V213A
attempts to sustain the current, which it oes by re
ucing its plate resistance, thereby pulling the Miller
tube gri ownwar . During the perio of the run up,
the timing-capacitor charging current is kept essen
tially constant by action of the constant-current tube.
The charging current remains constant within about
a tenth of a per cent, but the time base is not this
linear because of the variation of capacitance with
voltage of the timing capacitors.
The sawtooth voltage is fe to the output amplifier
through catho e follower V221A by means of a volt
age ivi er so that horizontal positioning can be ac
complishe . Catho e follower V221B prevents gri
current from flowing in the positioning circuit, an
catho e follower V222A prevents gri current from
flowing in the MAG-NORM fee back network. This
network re uces the net gain of the horizontal ampli
fier by a factor of five in the NORM position, an
permits the full gain to be realize when it is in the
MAG position.
The horizontal-output amplifier stage is a catho e-
couple phase inverter with a catho e-follower coup
ler to each eflection plate. Use of the catho e fol
lowers to rive the eflection plates increases the
horizontal ban wi th by a factor of about three times.
Magnifier
A egenerative network between the plate of V224B
of the output amplifier to the gri of catho e follower
V222A re uces the loop gain by a factor of five in
the NORM position of the MAG-NORM switch. In
the MAG position, the network is opene to permit
the amplifier to operate at full gain. The MAG POSI
TION screw river control permits the c level of the
catho e follower to be set at the same value for both
positions. Another screw river a justment labele
MAG GAIN ADJ on the chassis permits the magni
fie time base to be ma e exactly five times the nor
mal time base. The HORIZ POSITION control pre
ce es the magnifier circuits an therefore positions
for both the magnifie an the normal time bases.
TYPE 315D SECTION III, PAGE 2

Vertical Amplifier
VI is a twin-trio e with the two sections operate
in parallel. The signal is taken from the common
catho e connection of VI an applie to the catho e
of V2A. V2A is operate as a groun e -gri ampli
fier. V2B is a catho e-follower output coupler be
tween V2A plate an V3 gri . The preamplifier is
use only on the AC, .01 VOLTS/DIVISION posi
tion of the AMPLITUDE selector switch. In this
switch position, switch section SW1B connects the
input terminal through Cl to the gri of VIA an B,
an SW1C connects the catho e of catho e-follower
V2B to the gri of V3 through a protective network.
R1S is a screw river a justable resistor to permit the
preamplifier gain to be a juste accurately to ten
times. LI an L2 are series peaking coils to improve
high-frequency response.
V3 an V4 form a catho e-couple gain-control
stage. The signal is applie to the gri of V3 an
couple through the common unbypasse catho e con
nection to V4 which operates as a groun e -gri
amplifier. The MULTIPLIER switch, SW2, connects
any one of three resistor networks or a short circuit
between the two catho es to control the stage gain.
In the XI position, the catho es are connecte to
gether an the gain is at a maximum. In the 10-1
position, an a justable resistor is connecte between
catho es to permit continuous a justment of gain.
R51 an R53 connecte into the circuit in the other
two positions of the switch are screw river a justable
to permit the gain to be a juste to one-half or to
one-fifth accurately so as to accommo ate the gain
tp the calibrations of the graticule. R34 is a protective
resistor which limits the positive excursion of V3 gri
in case a high c voltage is connecte to the input
connector in the c position of SW1. C14 bypasses
R34 at higher frequencies.
Plate output from V4 fee s through the elay net
work to the gri of V8B, a catho e-follower output-
cupling tube. R59 terminates the elay network
through C21 to groun . (C21 is physically locate on
a bracket un erneath the elay-network assembly.)
The elay network elays the vertical- eflection sig
nal long enough to permit the portion of the wave
form that has triggere the sweep to be isplaye on
the crt screen.
The output amplifier consists of V10 an VI1 in
parallel, in a catho e-couple groun e -gri phase-
inversion circuit with V12 an V13 in parallel. The
c gri voltage of V12 an V13 is use for vertical
positioning. This voltage is controlle by V8A, a
catho e-follower voltage regulator whose gri volt
age is obtaine from potentiometer R70, labele
VERT POSITION, connecte between groun an
+100 volts. R65 an R66 limit the positioning range.
R90, a part of the coupling between catho es of
V10, Vll an V12, V13, is a screw river a justable
resistor whose shaft is mounte coaxially with the
AMPLITUDE control knob. This a justment per
mits the gain of the amplifier to be accommo ate to
the calibrations of the graticule.
L3 in the gri circuit an L4, L5, L6, an L7 in the
plate circuit provi e frequency compensation.
An internal triggering signal connection from the
plate of V3 to the trigger-selector circuits permits the
sweep circuit to be triggere by the observe signal.
In all other positions of the AMPLITUDE contro
SW1, than the previously- escribe AC, .01 VOLTS/
DIVISION position, the preamplifier is remove from
the circuit, an the INPUT connector is connecte to
the gri of V3, either through attenuators, or unatten
uate . In the AC portion of the control. Cl is con
necte in series with the INPUT connector. The gri
of V4 is groun e in these positions through switch
section SW1D, an V3 an V4 become a catho e-
couple groun e -gri amplifier.
The compensate input attenuators to the gri of
V3 are voltage ivi ers in which parallel capacitor an
resistor voltage ivi ers have the same ivision ratio.
C3 in the 10-to-l ivi er an C6 in the 100-to-l i
vi er permit a justment to be ma e of the capacitive
voltage ivision so that the high-frequency ivision
ratio is the same as the low-frequency ivision ratio.
C2, C5, an CIO are a justable so that the same
input capacitance will exist at all AMPLITUDE
switch positions. This is necessary when the probe
is use because the probe is compensate for the input
capacitance, an w'oul otherwise nee to be re
a juste for each switch setting. C15 connecte be
tween gri of V3 an screen of V4 is a neutralizing
capacitor that re uces the change in input capacitance
that occurs when the MULTIPLIER switch inserts
the various coupling resistors between catho es of
V3 an V4.
The MULTIPLIER switch, SW2, selects the
amount of coupling between catho es of V3 an V4 to
etermine the gain of the amplifier when the pre
amplifier is switche out. The VERT ATTEN ADJ
is a chassis-mounte screw river a justable potentio
meter connecting the catho es of V3 an V4 to
—150 volts. This control operates ifferentially. When
it increases the resistance to the catho e of V3 it simul
taneously ecreases the resistance to the catho e of
V4. When it is properly a juste , the c voltage at
the two catho es is the same an no change in vertical
SECTION III, PAGE 3 TYPE 315D

positioning occurs when the multiplier switch connects
larger of smaller resistors between them.
Calibrator
The calibrator provi es four squarewave voltages
of 100 volts, 10 volts, 1 volt an 0.1 volt, available
at a UHF coaxial fitting on the front panel but not
connecte internally to the vertical amplifier. The
source of squarewave voltage is a self-excite sym
metrical ac-couple multivibrator operating at a repe
tition frequency of about one kilocycle. The catho e
an gri s of this multivibrator are returne to
—150 volts.
During the con ucting perio of V601B, the gri
of V601A is below—150 volts an the A-section plate
is cut off. V602B gri is irectly connecte to V601A
gri an V602B plate is therefore also cut off uring
this perio .
During the con ucting perio of the A section of
V601, gri s of V601A an V602B are both high an
the plate of V602B is own below groun potential.
The gri of catho e-follower V602A is irectly con
necte to V602B plate, an it therefore varies between
cutoff in the negative irection an a point near
100 volts in the positive irection, etermine by volt
age ivi er R610, R611, R612.
The catho e resistor of catho e-follower V602A is
ma e up of a voltage- ivi er string, R620, R621, R622,
R623, which are of such values that voltages of
10 volts, 1 volt an 0.1 volt, peak to peak, are pro uce
at the taps when the catho e voltage is set at 100 volts,
peak to peak.
R612, a screw river a justment labele CAL ADJ
on the chassis, permits the gri of V602A to be set at
such a level that the catho e will be at 100 volts when
V602B is cut off. Since this portion of the circuit re
mains connecte to the -(-225-volt supply when the
CALIBRATOR switch is turne to the OFF position,
the voltage calibration of the calibrator circuit can be
checke with a c voltmeter.
C603 in the gri circuit an C604 in the catho e cir
cuit of the catho e follower re uce a small transient
waveform istortion.
Power Supply
The power-supply transformer, T401, is capable of
operating satisfactorily over the range of frequencies
between 50 cps an 800 cps. The primary of this trans
former is woun in two 117-volt sections, normally
parallele for 117-volt operation, but they are ar
range to be easily reconnecte in series for 234-volt
operation.
Four selenium full-wave bri ge rectifiers, each sup
plie with ac from a separate section of the trans
former secon ary, provi e c to four electronic volt
age regulators from which are obtaine the regulate
voltages of —150 volts, -(-100 volts, +225 volts an
+350 volts. In a ition to these four regulate volt
ages, two unregulate voltage sources are provi e ,
one at a nominal +330 volts from a tap taken ahea
of the +225-volt regulator, the other at a nominal
+420 volts taken from a tap ahea of the +350-volt
regulator.
The regulator will regulate satisfactorily over a
primary input-voltage range between 105 an 125
volts, or between 210 volts an 250 volts.
Five 6.3-volt secon ary win ings furnish heater
power for the various parts of the instrument, an for
the pilot light an graticule illumination.
Force -air cooling is provi e by a blower fan. Two
fan types are available. If the Type 315D oscilloscope
is to be use only on 50- to 60-cycle supply voltage,
a 60-cycle fan is recommen e , an is or inarily sup
plie with the instrument. If higher frequencies of
input voltage are to be use , however, a c fan an
rectifier are available at extra cost which will operate
over the same range of frequencies that the trans
former will.
Negative 150-Volt Regulator
The basic source of reference voltage is a type 5651
voltage-regulator gas io e, V401, in the catho e cir
cuit of V402, a voltage-comparator tube. Voltage-
ivi er string, R409, R410, R411, connecte between
regulate —150 volts an groun , is tappe at a voltage
above —150 volts approximately equal to the voltage
across the reference tube, V401, an connecte to the
gri of V402. This sets the catho e an gri of V402
at approximately the same voltage, an any change
in voltage at the —150-volt bus becomes a change in
gri -to-catho e voltage at V402. This change is
amplifie in V402 an applie irectly to the gri s of
V403 an V404, two series-regulator tubes connecte
together in parallel in the groun lea of the power
supply. If the —150-volt bus ten s to go negative
below this voltage, for example, the catho e of V402
will rop thereby increasing V402 plate current. In
crease plate current will lower V402 plate, which
will pull own the gri s of V403 an V404, thereby
increasing their plate resistance, so that they insert
a higher rop in the groun lea , an the —150-volt
bus will rise in the irection to correct the original
TYPE 315D SECTION III, PAGE 4

negative ten ency. C404, bypassing R407, R409, an
part of R410, improves the ac gain of the comparator
circuit an re uces ripple. R410 is a justable by a
screw river a justment labele 150 V ADJ on the
chassis, so that this voltage can be set accurately.
ioo-Volt Regulator
The + 100-volt supply is regulate by comparing
to groun in comparator-tube V421, a voltage near
groun on voltage- ivi er R424, R425, connecte be
tween —150 volts an the regulate -(-100-volt bus.
The ifference voltage is amplifie in V421 an ap
plie to the gri of series-regulator tube, V422, con
necte in series with the positive lea . C421 improves
the ac gain an re uces ripple. C420 filters the un
regulate c input to the regulator, an C422A, one
of three capacitors in one can, filters the regulate
portion.
-|-225-Volt Regulator
The -f-225-volt supply is regulate by comparing
to groun potential in comparator tube V441, the volt
age near groun potential on voltage ivi er R444,
R445, connecte between —150 volts an the regu
late -(-225-volt bus. The ifference voltage is ampli
fie in V441 an applie to the gri of series-regulator
tube V442A, connecte in series with the +225-volts
bus. Dc input to this regulator is supplie from a
secon rectifie an filtere but unregulate source
connecte in series with the previous source. C440
filters the unregulate input to the regulator. A tap
ahea of the regulator provi es a nominal +330 volts,
unregulate . C442B, the secon of three capacitors in
one can, filters the regulate supply at +225 volts.
R443, bypassing the series-regulator tube, increases
the available current at the regulate bus. C441 in
creases the regulator ac gain to re uce ripple.
50-Volt Regulator
The +350-volt supply is regulate by comparing
to groun potential the voltage near groun potential
on voltage- ivi er R467, R468, connecte between
—150 volts an the regulate +350-volt bus, in com
parator tube V461. The ifference voltage is ampli
fie in V461 an applie to series-regulator tube
V442B in series with the +350-volt bus. Dc input to
this regulator is supplie from a thir rectifie an
filtere , but unregulate source connecte in series
with the previous two sources. C460, in series with
C440 of the previous supply, filters the unregulate
input to the regulator. A tap is taken off ahea of the
regulator at a nominal +420 volts, unregulate .
C422C, the thir of three capacitors in one can, filters
the regulate +350-volt bus. R465, bypassing the
series-regulator tube increases the current available
at the regulate bus. C461 increases the regulator ac
gain to re uce ripple.
R412, a front-panel control labele SCALE ILLUM,
is a variable resistor in series with the graticule illumi
nating lights which permits the brightness of the
graticule illumination to be varie .
High-Voltage and Cathode-Ray Tube Circuits
Accelerating voltage of about —1500 volts is ap
plie to the catho e of the catho e-ray tube. This high
voltage is obtaine by rectifying a 50- to 60-kilocycle
high-voltage alternating current supplie by an oxi e-
core transformer whose primary forms the in uctor
of an in uctance-capacitance oscillator. The primary
in uctance is center tappe so that it can be use in
a Hartley oscillator. C804 is the tank capacitor an
V803 is the oscillator tube. Plate power is fe by way
of the center tap on the in uctor at a nominal
+350 volts from the unregulate si e of the regulate
+225-volt supply. V804 in the negative lea of the
high-voltage win ing is the rectifier supplying c to
the crt catho e. The rectifier filaments are supplie
from a itional win ings on the same transformer.
The positive en of the transformer win ing is con
necte to regulate +225 volts. Filtering is provi e
by C815 connecte to groun from V804 plate,, an
by C816 an C817 in series, also between V804 an
groun .
A voltage- ivi er string of resistors, R902, R903,
R904, R817, an R816 connecte between the rectifier
plate an regulate +350 volts provi es voltage taps
for the focusing gri an for a sample of the high
voltage for use in the high-voltage regulator system.
R903 of the resistor string is a front-panel control
potentiometer labele FOCUS which permits the volt
age of the focusing gri to be a juste for best focus.
R817 in the resistor string is a screw river-a just
able potentiometer, the arm of which is at about
—150 volts. The voltage from the arm is compare to
—150 volts in comparator tube V801A. The plate of
V801A is connecte to +350 volts through a very
high resistance loa , R802, an sits near groun po
tential. The gri of V801B is connecte irectly to
the plate of V801A, an the plate of V801B is con
necte irectly to the screen of oscillator-tube V803
an through plate-loa resistor R803, to regulate
+225 volts. Any eparture of the voltage tap on R817
of the high-voltage resistor string is therefore first
amplifie in comparator tube V801A an again in
V801B so as to change the screen voltage of V803.
For example, if the oscillator voltage becomes too
high, the gri voltage of V801A will rop, its plate
@SECTION III, PAGE 5 TYPE 315D

will rise carrying V801B gri up with it. Plate cur
rent in V801B will increase, its plate will rop carry
ing the screen of oscillator V803 own with it, thereby
re ucing the gain of this tube so that the oscillation
amplitu e will rop.
Unblan ing
A secon high-voltage win ing an rectifier supply
the control gri of the catho e-ray tube at about
—1600 volts. V805 is the rectifier an C818 is the filter
capacitor. R910, in a voltage- ivi er resistor string
across the high voltage is a justable by means of a
front-panel control labele INTENSITY to permit
a justment of the spot intensity.
The positive en of this supply is connecte to the
unblanking-output tube, V210A, through R914. Thus
the whole control-gri voltage supply inclu ing the
transformer win ing is raise an lowere in voltage
by the unblanking pulse. This arrangement provi es
c coupling of the unblanking waveform to the con
trol gri , thereby making it possible to use as slow a
sweep as esire . R914 an C902 improve the rise
time of the pulse appearing at the control gri .
The astigmatism control, labele ASTIG on the
front panel is a potentiometer, R920, connecte be
tween regulate +225 volts an regulate +100 volts.
An external catho e connection is provi e via C901
for intro ucing external z-axis signals to provi e
beam-intensity mo ulation if esire . R905 prevents
c, which might leak through the ielectric of C901,
from eveloping high voltage at the connector.
Components shown on the right of the broken line
in the iagram are locate on a horizontal bakelite
mounting boar above the en of the catho e-ray tube.
The transformer, rectifier tubes, an filter capacitors
shown on the iagram to the left of the broken line,
are mounte insi e a shiel at the left lower rear cor
ner to the left of the power transformer.
TYPE 315D SECTION HI. PAGE 6

SECTION IV
Ma ntenance and Adjustment
Filter Maintenance
Care must be taken to assure free ventilation of the
instrument inasmuch as some of the components are
operate at issipation levels such that excessive tem
peratures will result without a equate air circulation.
Washable Lumaloy Air Filters are use at the air
intake ports of the instrument. The following filter
cleaning instructions are given by the filter manu
facturer.
“To Clean:
(1 If grease or dirt load is light, remove filter front
installation and flush dirt or grease out of filter
zvith a stream of hot water or steam.
(2 If load is too heavy for treatment in (1 above,
prepare mild soap or detergent solution (see
paragraph below on use of caustics in pan or
sink deep enough to cover filter when laid flat.
Agitate filter up and down in this solution until
grease or dirt is loosened and carried off filter.
(3 Rinse filter and let dry.
(4 Dip or spray filter with fresh Filter Coat, or
other approved adhesive. Filter Coat is avail
able from the local representative of RE
SEARCH PRODUCTS CORP. in the one-pint
Handi-Koter with spray attachment or one-gal
lon and five-gallon containers.
In most cases hot water, steam, or hot water and
mild soap solution (Ivory, Dr eft, Vel, etc. is all
that is needed to restore the dirt or grease laden filter
to its original sparkling lustre. However, where ex
treme conditions are encountered with higher-than-
average dirt or grease loads or where maintenance
of the filters has been neglected, allowing an accumu
lation of hard grease or caked dirt, more compre
hensive cleaning steps may be taken.
CAUTION: IN CASES OF THIS KIND,
USE OF CAUSTICS WITHOUT RECOM
MENDED INHIBITORS ADDED IS DAM
AGING TO THE FILTER.
(For information on correct procedure, write the
Research Products Corporation stating name of
cleaning agent and concentration. Certain nation
ally known and nationally distributed cleaners are
approved for use in dish-washers, cleaning tatfks or
filter service company equipment. Following is a
partial alphabetical list of cleaners already tested and
approved by Research Products Corporation:
CLEANER
Calgonite
K O L
Oakite Composition
No. 63
Pan Dandy
Super Soilax
Wyandotte Keego
MAKER
Calgon, Inc.
DuBois Company
Oakite Products, Inc.
Economics Lab., Inc.
Economics Lab., Inc.
Wyandotte Chem. Corp.
Non-inclusion of any other cleaners is not intended
to indicate their being unacceptable. For specific in
formation on other products, write the Research
Products Corporation, Madison 10, Wisconsin.’’
Replacement of Components
Most of the components use in the construction of
TEKTRONIX instruments are stan ar parts obtain
able from any well-equippe parts istributor. Some
of the components carrying 1% an 2% tolerances
may not be so rea ily obtainable but may be pur
chase from the manufacturer at these tolerances. The
remain er of the low-tolerance components are
stan ar 10%- an 20%-tolerance parts that are
checke at the factory for proper value or performance.
Replacement parts are available on or er from the
factory at current net prices but in the case of stan ar
parts it is probably more economical of time to pur
chase them locally. It is not feasible to attempt to
check out low-tolerance parts or matche pairs with
out a reasonably large stock to choose from as the
rejection percentage is quite high in many cases.
IMPORTANT: It is imperative that you
get parts-or ering information from the in
struction book prepare specifically for the
instrument involve . The serial number of
the instruction book must agree with the
serial number of the instrument.
A TEKTRONIX instruction manual will usually
contain han -ma e changes of iagrams, parts lists,
an text, appropriate only to the instrument it was
prepare for. There are goo reasons why this is true.
First, TEKTRONIX engineers are continually
working to improve TEKTRONIX instruments.
When the improve circuitry is evelope or when
better components become available, they are put into
SECTION IV, PAGE 1 TYPE 315D

TEKTRONIX instruments as soon as possible. As a
results of constant improvement TEKTRONIX in
struments are always built as goo as we can buil
them, but the changes cause by these improvements
must frequently be entere by han into the manual.
Secon , when- TEKTRONIX instruments go
through our exhaustive test proce ure, TEKTRONIX
technicians a just them in ivi ually to obtain opti
mum operation. This kin of han tailoring occasion
ally requires substitution of components iffering from
the nominal values printe in the manuals.
Thir , because of procurement ifficulties, equiva
lent but ifferent parts are sometimes use . Usually
such parts are irectly interchangeable with those
originally specifie . No alternate parts have been
use which a versely affecte the instrument, an you
were able to receive your instrument much earlier
than you might have otherwise.
To assure that you will receive the correct replace
ment parts with the minimum of elay it is therefore
important that you inclu e the instrument serial num
ber with your or er, along with the instrument type
an part numbers, of course. An as a further pre
caution, get or ering information from the instruction
manual whose serial number agrees with the in
strument.
Equivalent parts, supplie by the factory when the
exact replacement parts or ere are not available, will
be accompanie by an explanation an will be irectly
interchangeable in most cases.
CAUTION: Use only silver-bearing sol er
on the ceramic terminal strips an for tin
ning the sol ering iron, if it becomes neces
sary to resol er.
The slots in the ceramic terminals are
fille with sol er containing 3 per cent of
silver which is bon e to a film of pure silver
fuse with the porcelain glaze. Or inary tin-
lea sol er absorbs the silver from the fuse
film to the extent that a bon can no longer
be forme between the sol er an the porce
lain after only a few resol ering operations.
Silver-bearing sol er is use in printe - an
etche -circuit techniques an is therefore
rea ily available from all principal sol er
manufacturers. A length of three-per cent
silver sol er inclu e with the instrument
will be foun mounte on the left si e of the
chassis.
Removal of the Case
Set the oscilloscope face ownwar on a pa e
flat surface, turn the two fasteners on the back ap
proximately % turn to the left, an lift off the case.
The power cor is not removable so it must be fe
through the hole as the cabinet is remove .
CAUTION: Voltages high enough to be
angerous are present in this instrument.
Since much maintenance must necessarily be
performe with the case remove , great care
shoul be taken to avoi contact with bare
lea s. Use only insulate tools, stan on a
ry floor, an if possible, keep one han in
your pocket.
Power Supply
Line Voltage
The power supply of the Type 315D Oscilloscope
will operate satisfactorily over the voltage ranges 105
to 125 volts an 210 to 250 volts.
The power transformer is woun with two 117-volt
primaries. When the instrument leaves the factory,
the primaries are or inarily connecte in parallel for
117-volt operation. If operation from 234-volt lines
is esire , remove the jumpers on the power trans
former between terminal 1 an terminal 2, an be
tween terminal 3 an terminal 4. Now connect termi
nals 2 an 3 together. With the line still connecte
to terminals 1 an 4, the instrument is rea y for
234-volt operation.
The fuse normally supplie when the Type 315D
is wire for 117-volt operation is 5-amp, 250-volt “Slo
Bio”. For proper protection on 234-volt operation,
this fuse shoul be change to 2l/2-amp, 250-volt
“Slo Bio”.
Line Frequency
The Type 315D is supplie in two ifferent mo els,
for universal line frequency 50 to 800 cycles, or for
50- to 60-cycle operation. The only ifference be
tween these mo els is in the fan motor supplie . The
universal 50-800-cycle mo el uses a c series-woun
motor with a full-wave selenium bri ge rectifier. A
37j/£-volt win ing on the power transformer supplies
the power to the rectifier. (NOTE: A few of the
early instruments i not have this win ing but rather
use a half-wave rectifier an a series resistor con
necte irectly to the 117-volt line.)
Change of Fan Motor
The 60-cycle mo el uses a stan ar 60-cycle sha e -
pole 117-volt motor. This motor, having no brushes,
will run quieter an the life shoul be longer than
the c mo el. This motor is recommen e where the
universal feature is not nee e . The mounting plates
are i entical on the two motors so it is possible to
TYPE 315D SECTION IV, PAGE 2

change from one to the other if the nee shoul arise.
If wire for the 60-cycle motor, the motor wires (grey)
shoul go to terminals 1 an 3. If wire for universal
line frequency, the wires shoul go to terminals 14
an 17. A name plate on the back of the instrument
in icates the line frequency. This plate shoul be
change if the motor is change .
Dc Voltages
All c voltages are regulate an are referre to the
—150-volt supply. In or er for the instrument to per
form properly, it is necessary for the minus 150-volt
supply to be within plus or minus 2% of this
value. The voltage shoul be checke with an accu
rate voltmeter an correcte if necessary by a justing
potentiometer R410 marke ADJUST —150V (screw
river a just), locate on the center bulkhea . This
check shoul always be ma e if the 5651 tube V401
is change .
High Voltage
The calibration of the TIME BASE an VERTI
CAL AMPLITUDE controls are epen ent on the
acceleration voltage applie to the catho e-ray tube.
If it is suspecte that the calibrations are off, the high-
voltage supply shoul be checke with an accurate
meter of at least 20,000 ohms-per-volt sensitivity. The
supply voltage shoul be a juste to—1800 volts from
the catho e (pin 3) of the CRT to groun by means of
the potentiometer R817 marke H.V. ADJUST. If
more convenient, this rea ing may be ma e from the
plate of V804 (heavy green lea ) to groun . V804 is
the lower rectifier tube locate un er the shiel .
Calibrator
Before a justments are ma e on the vertical ampli
fier, it is well to check the output a justment of the
calibrator. Inasmuch as the clipper, catho e-follower
V602A, remains con ucting even with the CALI
BRATOR switch in the OFF position, it is possible
to a just the voltage accurately with a c voltmeter.
An accurate voltmeter of at least 1000 ohms-per-volt
sensitivity shoul be connecte to the catho e (pin 3)
of V602A. (This is the yellow lea going to the back
of the CALIBRATOR switch.) The switch shoul
be turne to the OFF position an R612 (screw river
potentiometer marke CAL ADJ on the main bulk
hea ) a juste to a rea ing of +100 volts. The cali
bration voltage will then be accurate on all settings.
Vertical Amplifier
NOTE:A warm-up perio of approximatel
15 minutes to stabilize the characteristic
shoul prece e a justments of the vertica
amplifier. Also best results will be obtaine
if the a justments are ma e in the following
or er:
Amplifier Gain Adjustment
Set the AMPLITUDE selector switch to the c
position, .1 VOLT/DIV. Set the MULTIPLIER to
1; set the CALIBRATOR to 1. Connect a lea be
tween CAL OUTPUT an INPUT, with the STA
BILITY control a vance so the time base is free run
ning. A just the VERT POSITION control until the
bottom of the isplay coinci es with the lowest small
mark on the graticule. Then a just R90 (screw river
a justment in center of AMPLITUDE knob) until
the top of the isplay coinci es with the top small
mark on the graticule (10 ivision). The CALI
BRATOR voltage shoul be set to .1 an the isplay
shoul occupy one scale ivision at any setting of
the VERT POSITION control.
iX MULTIPLIER Adjustment
The CALIBRATOR shoul again be set to 1 volt
an the MULTIPLIER set to 2. R51 (locate on the
outsi e of the bracket supporting the MULTIPLIER
switch) is a juste to give a isplay of 5 ivisions.
$X MULTIPLIER Adjustment
Next set the MULTIPLIER switch to 5, a just R53
(locate on the insi e of the bracket) to give a isplay
of 2 ivisions. With the MULTIPLIER switch in the
10-1 (re ) position, a full rotation of the center (re )
knob will now give a isplay of 10 ivisions in the
full-clockwise position an approximately 1 ivision
in the counter-clockwise position.
Attenuator Adjustment
Now turn the CALIBRATOR to OFF an position
the trace to the center of the screen. As the re knob
(10-1) on the MULTIPLIER is rotate , there shoul
be no change in position. If there is a change in posi
tion, R55, VERT ATTEN ADJ (locate on si e of
vertical amplifier chassis) shoul be a juste until
there is no change in position as the re knob is
rotate .
NOTE: This a justment as well as the
PRE AMP GAIN ADJ may require an occa
sional touching up as the tubes age. There
fore holes have been provi e in the si es of
the cabinet to allow access to these controls,
PREAMP GAIN Adjustment
Set the CALIBRATOR to .1 volt, set the AMPLI
TUDE to .01 VOLTS/DIVISION, MULTIPLIER
to 2. A just R15, labele PRE AMP GAIN ADJ,
locate on si e of vertical amplifier chassis, to give
a isplay of 5 scale ivisions.
SECTION IV, PAGE 3 TYPE 315D

Input Attenuator and Probe
The various input attenuators in the Type 31SD are
of the resistor-capacitor type. The resistor ivi er
ratio is equal to the capacitor ivi er ratio, an there
fore the voltage ivision is constant for any frequency
from c to well above the requirements of the instru
ment. A justments of these attenuators is rea ily
ma e while observing their square-wave response.
The self-containe calibrator in the Type 315D is a
suitable square-wave source, an thus a check of the
attenuators is always available. When the variable
capacitors in the attenuators are properly a juste , a
square wave will be correctly repro uce by the oscil
loscope. If the capacitive ivi er has a lower attenu
ation than the resistive ivi er, a spike will appear on
the lea ing e ge of the square wave. If the capacitive
ivi er has a higher attenuation, the corner of the lea 
ing e ge will be roun e . The following a justment
proce ure is recommen e :
Shield
1. Lay a sheet of metal on the top of the in
strument to simulate the presence of the case.
C3 Adjust
2. Set the CALIBRATOR to 10 volts. Set the
AMPLITUDE to AC, 1 VOLT/DIV an the
MULTIPLIER to 2. With the TRIGGER SE
LECTOR set to +INT, SLOW RISE, a just
the TIME BASE to isplay 8 to 10 cycles of the
CAL waveform across the screen. A just C3, the
rear trimmer, on the si e of the switch.
C15 Adjust
3. Turn the MULTIPLIER to the 10-1 posi
tion (re ), set the center knob full counter-clock
wise, an set the CALIBRATOR to 100 volts.
A just C15, locate on the chassis just in
the rear of the MULTIPLIER switch, until no
overshoot is observe . (NOTE: It may be
necessary to repeat step 2 after this a justment
as there is some interaction.)
C6 Adjust
4. Set the AMPLITUDE to AC, 10 VOLTS/
DIV, set the MULTIPLIER to 2, set the CALI
BRATOR to 100. A just C6 (locate on the rear
of the switch, an a juste through the hole in
the chassis.)
Probe Adjust (C101
5. Remove the wire connecting CAL OUT an
INPUT, an connect the probe, place the tip of
the probe in CAL OUT. Set AMPLITUDE to
.1 VOLT/DIV, MULTIPLIER on 2, an set the
CALIBRATOR on 10. A just C101, locate on
the probe bo y.
C2 Adjust
6. Set AMPLITUDE to 1 VOLT/DIV,
MULTIPLIER on 2. Set CALIBRATOR to
100 volts. A just C2, locate on the si e of
AMPLITUDE switch.
C5 Adjust
7. Set AMPLITUDE to 10 VOLTS/DIV,
MULTIPLIER on 1, with the CALIBRATOR
at 100 volts. A just C5, locate on the front of
the AMPLITUDE switch, through the hole on
the chassis.
Cro Adjust
8. Set the AMPLITUDE to .01 VOLTS/DIV,
MULTIPLIER on 2, with the CALIBRATOR
on 1 volt. A just CIO, locate near VI on the
front of the vertical amplifier chassis.
High-Frequency Compensation
The following escribes the a justment proce ure
for high-frequency compensation in the Type 315D.
The a justments are not extremely critical. However,
they o require consi erable care to obtain optimum
results. Also since once a juste , they are fairly
stable, rea justment shoul not be attempte with
out first eliminating other possible sources of wave
form istortion, inclu ing efective tubes or a efi
cient signal source. A suitable square-wave generator
or pulser is necessary in making any high-frequency
a justments of the Type 315D. The square-wave gen
erator rise time must not excee .04 microsecon s. A
TEKTRONIX Type 104A or Type 105 Square-wave
Generator will provi e a suitable signal. All connec
tions between the generator an the oscilloscope
shoul be coaxial type an MUST be properly termi
nate , preferably at both en s of the cable.
Disconnect Delay Network
1. In the Type 315D, the DELAY NETWORK
must be isconnecte before any a justments are
ma e on the vertical amplifier. This can be one as
follows:
Disconnect the re lea ( elay line input) from
pin 6 (plate) of V4.
Disconnect the purple lea ( elay line output)
from pin 7 (gri ) of V8B.
Connect a jumper from pin 6 of V4 to pin 7 of
V8B. This lea shoul be no longer than neces
sary an shoul be kept well away from the
chassis.
Connect a 1000-ohm, 1-watt, resistor from pin 7
of V8B to the +100-volt bus. The + 100-volt
bus is locate on the terminal of C21, which is
on the bracket below the elay network.
TYPE 315D SECTION IV, PAGE 4

Amplitude of Test Signal
2. Apply a square wave of 750 kc to 1 me to the
input of the Type 315 oscilloscope. A just the ampli
tu e of the square wave so that it causes a eflection
of 5 to 6 ivisions with the AMPLITUDE set on
.1 VOLTS/DIV an the MULTIPLIER on 1 or 2.
3. A just the TIME BASE to isplay 3 or 4 cycles
of the square wave.
Compensating Coil Adjustments
4. Observe the lea ing e ge of the square wave.
A just L3, L4, L5, L6, an L7, if necessary, for the
best waveform with the least overshoot on the lea ing
e ge of the wave. All of these a justments interact
to some extent so only a small a justment shoul be
ma e to any one coil at a time. NOTE: If the above
steps are properly ma e, the waveform shoul look
very goo at this point. However, there may be a few
remaining small wrinkles. This shoul not cause con
cern as they will isappear when the elay line is
re-installe .
Preamp. Adjust
5. Insert a 10-to-l pa in the signal lea from the
generator, or re uce its output sufficiently that it will
not overloa the preamplifier. Set the AMPLITUDE
to .01 VOLT/DIV, a just LI an L2 for best wave
form. NOTE: These a justments are not very critical
an it may require a large change in in uctance to
show any change in waveform. The two coils shoul
be a juste so that the slugs are both in about the
same position.
6. The elay network shoul be reconnecte .
Delay Networ
The elay network is a 19-section, M- erive , arti
ficial transmission line provi ing a signal elay of
.25 microsecon . An accurate impe ance match be
tween sections must be maintaine to prevent reflec
tions. Each section is a juste by means of a variable
capacitor (C501 to C522). The effects of these a 
justments are istribute over the first .5 microsecon
of the signal.
CAUTION: A justment of the elay net
work shoul not be attempte without first
verifying normal transient response of the
output amplifier as explaine un er “HIGH-
FREQUENCY COMPENSATION”. Oth
erwise the elay network a justments may
be set to compensate for eficiencies in the
output stage. This will cause a loss in over
all ban wi th of the instrument. The follow
ing metho s of a justment will give satis
factory results:
Delay Network Test Signal
1. Apply a 100-kc square wave to the input of
the oscilloscope with the AMPLITUDE set on
.1 VOLTS/DIV. Set the TIME BASE to 1 MICRO-
SECOND/DIVISION.
2. A just the DELAY NETWORK trimmers
(C501 to C522) for the smallest ripple or irregularity
on the first .5 microsecon of the square wave. The
position of the irregularity etermines which capacitor
nee s to be a juste . Try a justing one of the center
capacitors to see where it pro uces its effect.
Leading Edge
3. Change the TIME BASE to 5 or 10 MICRO-
SECONDS/DIVISION an observe the squareness
of the lea ing corner. If the corner (first .5 microsec)
on is higher in amplitu e than the remain er of the
square wave, repeat step 2, but setting all the capaci
tors at a higher capacitance. If lower, repeat using
lower capacitor settings. It may be foun that only
part of the corner will slope up or own. In this case,
only part of the capacitors will nee to be increase or
ecrease .
Delay Network Terminating Resistor^
If a square corner cannot thus be obtaine , an in
correct termination resistor, R59 is in icate . To
check this termination, turn off the 315D an allow
the tubes to cool. Then measure R59 between pin 7
of V8B an the +100-volt bus (locate on terminal
of capacitor C21) with an accurate bri ge. If outsi e
the range of 1100 ohms ±1%, replace with a composi
tion resistor selecte to be within these limits. (R59
is locate in the elay-network chassis, which must
be remove to replace the resistor.)
Astigmatism
For best focus of both horizontal an vertical lines,
the final ano e of the catho e-ray tube must be re
turne to a voltage approximately equal to the c
voltage on the eflection plates. A preliminary set
ting of the ASTIGMATISM control (R920), locate
on the back plate of the instrument, may be ma e by
connecting a voltmeter between groun an the center
arm of this control, an a justing to +190 volts. Be
cause of variations in in ivi ual catho e-ray tubes,
the best setting may iffer slightly from this value,
so final a justment shoul be ma e while a signal is
being observe . The optimum setting will give equally
goo focus of both horizontal an vertical lines. This
shoul be ma e while a sine wave or a square wave
SECTION IV, PAGE 5 TYPE 3I5D

is being observe . This setting shoul be ma e simul
taneously with the front-panel FOCUS control be
cause these controls interact to some extent.
Time Base
A complete proce ure for the a justment an cali
bration of the time base is outline here. However, in
normal servicing, only necessary a justments shoul
be ma e.
Timing Series Capacitors
If it is ever necessary to replace one of the timing-
series capacitors (C280A, C280B, C280C^ C280D) it
is suggeste that all four capacitors be obtaine from
TEKTRONIX, INC., an be replace as a group.
When or ering replacement parts be sure to men
tion instrument type an serial number.
The timing series consists of one group of four ca
pacitors arbitrarily chosen from the six possible series
shown below.
Nominal
Value Series 7-K Series
7-L Series
7-M Series 7-N Series
7-P Series
7-Q
.96 .97 .98 .99 1.0 1.01
.097 .098 .099 .10 .101 .102
.Olpi .0097 .0098 .0099 .01 .0101 .0102
lOOO^f 970 980 990 1000 1010 1020
The values shown are minimum with a tolerance of
—oto+1%-
Multivibrator Stability
1. Set STABILITY control (re coaxial knob) full
clockwise. A just MULTI STABILITY (R254,
screw river potentiometer on si e of sweep eck)
about half way between the points where the sweep
stops on the left of the screen an where it stops on
the right of the screen. NOTE: It may not be possible
to make it stop on both si es. If not, a just it to
where it stops on one si e or the other, then back it
off approximately turn.
Sweep Length
2. With the sweep free running at 1 MILLI-
SEC/DIVISION a just SWEEP LENGTH (R261,
screw river a justment on si e of sweep eck) until
the sweep just covers the rule portion of the graticule
(approximately 10)4 ivision).
Trigger Sensitivity
3. Set the TRIGGER SELECTOR to -(-LINE or
—LINE. Set the time base RANGE to 10 MICRO-
SECONDS/DIVISION. Set the TIME BASE MUL
TIPLIER to 1. Set the VERTICAL AMPLIFIER
AMPLITUDE to .1 VOLT/DIVISION, MULTI
PLIER bn 1. A vance the STABILITY control (re
knob) until a trace appears. Now turn the STABIL
ITY control back (counter-clockwise) until the trace
isappears, or rops su enly in intensity. If the trace
isappears, a just the TRIGGER AMPLITUDE
DISCRIMINATOR until a im trace is isplaye .
The time base is now triggere by the ac line fre
quency. Connect, the 10X probe cable to the INPUT
an touch the probe to the catho e of V203 (pin 3
an 8). This lea appears at the terminal of the 18-k,‘
2-watt resistor (R232) locate on the terminal boar
just back of the TRIGGER SELECTOR switch on
the un ersi e of the sweep chassis. A just TRIG
SENS (R223, screw river control, locate on si e of
the sweep chassis) until a series of oscillations are
observe on the trace, then back off the control to
the point where the oscillations just isappear.
V 201 Balance
4. Set the TRIGGER AMPLITUDE DISCRIMI
NATOR to 0 (center), an set the STABILITY con
trol full counterclockwise. Connect a c voltmeter
between groun an the gri of the pento e section
of V202, pin 2, an rotate the TRIGGER SELECTOR
switch from the -(-EXT to the.—EXT positions. The
voltages in the two switch positions shoul be nearly
equal at 190 volts. If there is a ifference of over five
volts it in icates either that the phase-inverter tube,
V201, is not balance , or that the plate resistors for
this tube are not equal. V201 shoul be exchange if
necessary for a tube which gives as nearly equal volt
age as obtainable with the switch in the two positions,
an the resistors, R208 an R209, shoul be checke .
Internal-Trigger DC Level
5. With the controls set as in step 4, rotate the
TRIGGER SELECTOR switch from —INT to
-(-INT, an if necessary, a just R202 (a screw river
a justment on si e of TRIGGER SELECTOR
switch) until the average of the two voltages is the
same as the average voltage measure in step 4.
A. Set the AMPLITUDE selector to one of the
AC positions. Connect a wire between INPUT an
CAL OUTPUT. Set the CALIBRATOR an the
AMPLITUDE control so that a vertical eflection
of approximately 0.2 ivision is isplaye . Set TRIG
GER SELECTOR to +IN T or —INT, SLOW RISE.
Set the STABILITY control just below the point
where the sweep free runs. Set the TRIGGER
AMPLITUDE DISCRIMINATOR to 0 (center).
A just INT TRIG DC LEVEL (R202, screw river
a justment on si e of TRIGGER SELECTOR
switch) until the point of triggering occurs as close
as possible to the zero setting of the TRIGGER
TYPE 31SD SECTION IV PAGE 6

AMPLITUDE DISCRIMINATOR. This point
shoul be checke on both +IN T an —INT set
tings of the TRIGGER SELECTOR. When a proper
a justment is ma e, the point of triggering will be
at about the same rotation from zero with either posi
tive or negative settings.
NOTE: For the following step an for all
time-base calibration a justments, either a
suitable time-mark generator or an accu
rately calibrate oscillator is require . A
suitable instrument is the TEKTRONIX
TYPE 180 TIME-MARK GENERATOR.
V213 Check (Constant-Current Tube
6. Set the marker generator for one-microsecon
marks. Set the TIME BASE to 1 MICROSEC/DIVI-
SION, an the MULTIPLIER to 1. Display a stable
trace of the time marks, an watch the trace as you
short out R279 (15-ohm resistor in heater lea to
V213A, locate on bakelite boar on back of sweep
chassis). Keep R279 shorte for at least 30 secon s.
If any change occurs in the time base replace the
constant-current tube, V213. A tube shoul be se
lecte for this position which shows no change as the
heater voltage is change . A tube with low emission
or with high heater-to-catho e leakage is unsatisfac
tory in this position. High heater-to-catho e leakage
in this tube will cause an error in the timing of the
5 SEC/DIVISION range. If this trouble is suspecte ,
its presence can be checke by setting the RANGE
switch to 1 SEC/DIVISION an MULTIPLIER to
5, an a vance the STABILITY control to get a
recurrent sweep. Time the full 10-centimeter transit
time first with the line voltage near 105 volts an
secon with the line voltage increase to the vicinity
of 125 volts. Any ifference in the timing with a
change in line voltage in icates catho e-to-heater
leakage in the constant-current tube.
Time Base Calibration
7. Set the TIME BASE RANGE on 1 MILLI-
SECOND/DIVISION. Connect the time-mark gen
erator to the vertical INPUT an select time marks
of 1 millisecon . A just SWEEP CAL (R286, screw
river a just on si e of sweep chassis) until 10 marks
correspon with 10 scale ivisions.
Magnifier Gain
8. With the time marks an TIME BASE set as
in step 7, turn the 5X MAGNIFIER (re knob center
of RANGE switch) to the ON position (clockwise
rotation). The HORIZ POSITION shoul be set so
that the center 20 per cent of the isplay is on the
screen of the tube. A just MAG GAINV(R314, screw
river a justment on si e of sweep chassis) until 2
time marks correspon with 10 scale ivisions. A
more accurate a justment may be obtaine if the
generator is set to 100 MICROSECONDS. Then 20
time marks will occupy 10 ivisions. The linearity
of the sweep shoul be carefully checke by noting
if each time mark correspon s with a graticule ivi
sion. If there is any in ication that the sweep is not
linear, the horizontal output tubes (V224 an V223)
shoul be change .
Mag. Centering
9. With the same setup as in step 7, position the
trace to the right with the HORIZ POSITION con
trol, until the secon time mark as isplaye on the
screen is centere over the center line of the graticule
(magnifie sweep). Now turn the 5X MAGNIFIER
switch to OFF (counter clockwise) an reposition the
trace with MAG CENTERING (R306, screw river
a just, on si e of sweep chassis) until the secon time
mark is centere on the screen. When this a justment
has been properly ma e, there will be no movement
of the isplay in the center of the screen as the 5X
MAGNIFIER is switche on or off. In other wor s,
the trace will be magnifie equally in both irections
from center.
NOTE: At this point is recommen e that
all time-base ranges slower than 1 MILLI-
SEC/DIVI'SION be checke in each of the
three MULTIPLIER positions. There shoul
be no error greater than two per cent ex
cept at 1, 2, an 5 SEC/DIVISION settings,
where the error shoul not excee four per
cent. Any greater error in icates efective
timing resistors or capacitors, or, in the case
of the slowest time bases, heater-to-catho e
leakage in V213A excessive.
Preliminary Adjustment for High-Speed Trace Linearity
10. If the linearity of the time base has eteriorate ,
trimmers C260, C276, C290 an C303, locate on the
un ersi e of the sweep eck shoul be a juste for
best linearity first before the timing of the 10, 1, or
0.1 MICROSEC/DIVISION time bases is a juste .
If the linearity is goo , step 10 may not be necessary.
If the linearity nee s to be correcte , preset the trim
mers as follows:
C276, minimum capacitance
C303, minimum capacitance
C260, half capacitance
C290, half capacitance
®SECTION IV, PAGE 7 TYPE 3I5D

Then the following proce ure shoul be followe in
the sequence liste :
A. Set the TIME BASE RANGE to 10 MICRO-
SEC/DIVISION, MULTIPLIER to 1, an is
play 10-microsecon time marks. A just C290 for
best linearity of the first half of the time base.
B. Make a preliminary a justment of C280E (lower
capacitor on bracket on top of si e of chassis) so
that 10 markers correspon with 10 graticule
ivisions.
C. Change the RANGE control setting to .1 MICRO-
SEC/DIVISION an the MULTIPLIER setting
to 5. Display a five-megacycle sine wave an a 
just C276 for best linearity of the first half of the
sweep.
D. Re uce the MULTIPLIER control to 1, an a 
vance C250 until the en of the trace just starts
to fol over, an then back it off until no fol -
over occurs an the linearity of the last of the
trace is best.
E. A vance the MULTIPLIER ial to 2, an a just
C303 for best linearity of the start of the trace.
High-Frequency Timing
C290 Adjust
11. Set the RANGE to 1 MICROSEC/DIVISION,
the MULTIPLIER to 5, an turn the 5X MAGNI
FIER to ON. Set the marker generator to give
5-microsecon marks. With the HORIZ POSITION
control, position the isplay so that the first of the
sweep is observe . A just C290 so that the first two
markers occupy 10.1 graticule ivision.
C280E Adjust
12. With RANGE set to 1 MICROSEC/DIVI
SION set the MULTIPLIER to XI, an turn the
5X MAGNIFIER to OFF. Set the marker generator
to give one-microsecon marks an a just C280E (lo
cate on bracket on tube-si e of sweep chassis, lower
capacitor nearest switch) so that 10 time marks cor
respon with 10 scale ivisions.
C290 Readjust
13. With the RANGE set to 1 MICROSEC/DIVI
SION, set the MULTIPLIER to 5X an set the
marker generator for five-microsecon marks. Ob
serve the linearity of the sweep. Rea just C290, if
necessary, so that each time mark has the same spac
ing, without regar to timing. If much a justment
is necessary, step 12 shoul be repeate .
NOTE: With the RANGE set to 1 MICRO
SEC/DIVISION the timing accuracy shoul
be checke at the X2 an X5 MULTIPLIER
settings. Any error greater than 2% in icates
resistors R282A or R282B are efective. If
there is any iscrepancy it shoul be aver
age between the settings by a compromise
setting of C280E. Do not confuse timing
error with non-linearity of the sweep.
C280G Adjust (preliminary)
14. Set the RANGE to .1 MICROSEC/DIVI
SION, set the MULTIPLIER to 5 an set the marker
generator for 1-^sec marks. A just C280G so that 5
marks correspon with 10 scale ivisions.
C276 Adjust
15. With the same settings as in step 14, change
the marker generator to 5 me, an a just C276, if
necessary, for the best linearity at the start of the
sweep.
C280G Adjust
16. With the same settings as in step 15, change
the marker generator for 1-^sec marks an rea just
C280G, if nece'ssary, so that 5 marks correspon with
10 scale ivisions.
Adjust
17. With the same settings as in step 16 change
the MULTIPLIER to XI an set marker generator
to 10 me. A just C303 if necessary so that the center
8 scale ivisions correspon with 8 sine waves. Dis
regar the first an the last marks as there may be a
small error if they are use . It may be necessary to
repeat step 16 after this a justment is ma e. The tim
ing shoul now be checke in all positions of the
MULTIPLIER switch an if any error is foun it
in icates that the sweep-linearity-setting capacitors
C303, C276 or C260, are not properly a juste .
TYPE 315D SECTION IV, PAGE 8