Tektronix 321 A User manual

INSTRUCTION
MAN UAL
TYPE
321A
OSCILLOSCOPE
Tektronix, Inc.
S.W.
Millikan
Way
@
P.
O.
Box
500
@
Beaverton,
Oregon
97005
@
Phone
644-0161
@
Cables:
Tektronix
070-425
564

mentioned above should be taken up
your Tektronix Field Engineer.
ktronix repair and replacement-part
is geared directly to the field, there-
p all requests for repairs and replace-
nt parts should be directed to the Tek-
nix Field Office-or Representative in your
. This procedure will assure you the
t possible service. Please include. the
rument Type and Serial number with all
sts
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ifications and price change priv-
reserved.
erton, Oregon. Printed in the United
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ie copyright owner.

INTeNsiTY
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TYPE 321A
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SLOPE
The Type 321A Oxcilloscope
Type 321A

Type 321A
SECTION 1
CHARACTERISTICS
Introduction
The Tektronix Type 321A is a high-performance, de-to-6
mc, transistorized oscilloscope. Its light weight, small size
and ability to operate from a variety of power sources make
it a versatile field and laboratory instrument. The oscillo-
scope can operate from its internally-contained rechargeable
battery pack, an external de source or from a 115/230-volt
50-800 cycle ac line. Regulated power supplies in the instru-
ment, accurate calibration, and precise linearity assure exact
time and amplitude measurements despite normal voltage-
source and power-supply-load changes that occur under
actual operating conditions.
Operating temperature range derived from tests indicates
optimum performance and reliability on its self-contained
batteries from 0° to +40° C at altitudes up to 15,000 feet.
Temperature range without batteries when operating from an
external source is —-15° C to +55° C. Non-operating tem-
perature range is —55° C to +75° C without batteries
and —40° C to +60° C with batteries at altitudes to
50,000 feet.
For the operator's convenience, a front-panel battery light
indicates when the internal batteries are low. If external de
or ac operation is being used instead of the batteries, the
light turns on if the external voltage source drops too low
for proper power supply regulation.
A 4-position power switch on the front panel permits
convenient selection of charging rate and/or power source.
Vertical Deflection System
Bandpass—Dc to at least 6 me (3-db down) using de cou-
pling; using oc coupling, low-frequency 3-db down point
is 2cps typical from a 1-ke reference.
Sensitivity—0.01 v/div to 20v/div in 11 calibrated steps;
accuracy is within 3% of front-panel markings. Con-
tinuously variable from 0.01 v/div to bout 50 v/div
uncalibrated.
Input Impedance—35 pf nominal paralleled by 1 megohm
{::1%), 8.2 pf nominal paralleled by 10 megohms
(22%) when using the P6006 10X Probe.
Maximum Allowable Input Voltage Rating—600 volts com-
bined de and peak ac; 600 volts (not 1200 volts) peak-to-
peak ac.
Triggering
Type—Automatic, or amplitude-level selection using pre-
set stability,
Mode—Ac-coupled or De-coupled.
Slope—Plus, from rising slope of triggering waveform, or
minus from negative slope of triggering waveform.
Source—Internal from vertical signal, or external from
triggering signal.
Signal Requirements—Internal: 0.2 major division vertical
deflection at 1 ke increasing to 1 major division at 6 me.
External: 1 volt peak-to-peak at 1 ke increasing to 3 volts
peak-to-peak at 6mc. Nominal input impedance: 5 pf
paralleled by 100 kilohms (-+-20%).
Sweep
Type—Miller Integrator.
Sweep Rates—0.5 ysec/div to 0.5 sec/div in 19 calibrated
steps. Accurate 5X sweep magnifier extends calibrated
range to 0.) ysec/div, Calibrated sweep-rate accuracy
is -+3%. Sweep time adjustable between steps and to
21.5 sec/div uncalibrated.
External Horizontal Input
Bandpass—Dc to at least 1 me (3-db down).
Deflection Factor—I v/dv +10% with 5X magnifier on.
Input Impedance—30 pf typical paralleled by 100 kilohms
{5%).
Amplitude Calibrator
Square Wave—Frequency about 2 kc.
Amplitude—500 mv peak-to-peak. Also 40 my peak-to-
peak internally coupled in CAL 4 DIV position of VOLTS/
DIV switch. Peak-to-peak amplitude accuracy is +3%.
Cathode-Ray Tube
Type—Special Tektronix-manufactured T3211, 3” flat-face,
post-deflection accelerator. Low heater power.
Accelerating Potential—4 kv.
Z-Axis Modulation—External terminal permits RC coupling
to crt grid.
Unblanking—Deflection unblanking.
Phosphor—Type P31 normally furnished; Pl, P2, P7, and
P11 phosphors optional. Other phosphors furnished on
special order.
Graticule
Ilumination—Variable edge lighting when operating from
ac line.
Display Area—Marked in 6-vertical and 10-horizontal 1/4“
divisions.
Power Requirements
Source—Operates from 10 size D flashlight cells, or 10
size D rechargeable cells (approximately 3 hours using
2.5 ampere-hour cells; approximately 5 hours using 4

Characteristics —- Type 321A
ampere-hour cells), or 11.5 to 35 volts de (aircraft, auto,
boat, etc,), or 103.5 to 126.5 volts or 207 to 253 volts,
rms, 50 to 800 cycles, single-phase ac.
Power Consumption—Approximately 700 ma from internal
batteries or external de source; 20 watts nominal at
115-volt ac fine.
Temperature Protection—-Thermal cutout switch interrupts
power if ambient temperature exceeds 131° F (55° C).
Built-in battery charger is standard equipment.
Environmental Capabilities
Vibration (operating)-—0.025" peak-to-peak, 10 to 55 to
lO cps in 1 minute sweeps (4 G's) for 15 minutes on
each axis. Three-minute vibration at resonance or
55 cps on each axis.
Shock (operating}—20 G's, Y2 sine, 11-msec duration.
Two shocks each direction along each of the three
major axis: bottom, top, left side, right side, front
and rear. Total of 12 shocks.
Shock {non-operating)—60 G's, ¥% sine, 11-msec duro-
tion. One shock each direction along each of the three
major axis; total of 6 shocks.
Humidity [non-operating)—Meets Mil-Std-202B, method
106A (except freezing and vibration) through 5 cycles
(120 hours).
Transit (non-operating)—Meets National Safe Transit test
when factory packaged. Vibration for one hour at
slightly greater than one G, Eighteen-inch drop in any
orientation,
Mechanical Specifications
Construction—Aluminum alloy chassis and cabinet.
Finish—Anodized panel, blue vinyl-finish cabinet.
Dimensions—8'/," high, 5%,” wide, 16” deep overall.
ACCESSORIES
Information on accessories for use with this instrument is
included at the rear of the mechanical parts list.

SECTION 2
PRELIMINARY INSTRUCTIONS
Power Requirements
The regulated power supplies in the Type 321A will operate
form 115-v or 230-v rms ac line, from an external de source
(11.5 to 35 volts), or from a “battery pack” consisting of
either 10 size D flashlight cells or 10 size D rechargeable
cells.
Fuse Data
Use only the recommended fuses in the Type 321A Oscil-
loscope. The upper fuse, F621 (see Fig. 2-1), is a 1.5-amp
3AG Fast-Blo; the lower fuse, F601, is a .25-amp 3AG Fast-
Blo. Neither fuse needs to be changed if the oscilloscope
is converted from one line voltage to the other (I115v and
230 v).
volt operation, so these connections do not have to be
changed when converting from one line voltage to the other.
When wired for 115-volt operation, terminals 1 and 2 are
joined by a bare bus wire, and terminals 3 and 4 are simi-
larly joined, as shown in Fig. 2-2[a). To convert to 230-
volt operation, remove the bare bus wires between these
terminals and substitute a single connecting wire between
terminals 2 and 3, as shown in Fig. 2-2(b).
To turn on the Type 321A when the power cord is con-
nected to the oscilloscope power connector and to the ac
voltage source, set the POWER switch to EXT ON. To turn
off the oscilloscope, set the POWER switch to TRICKLE. The
TRICKLE position can be regarded as the normal “off” posi-
tion for the instrument.
Fig. 2-1. Location of fuses and Charger switch (left-side view).
Ac Operation
Unless tagged otherwise, your instrument is connected at
the factory for operation at 103.5 to 126.5 volts, 50 to 800
cycles ac (115 volts nominal), However, provisions are made
for easy conversion to operate at 207 to 253 volts, 50 to
800 cycles (230 volts nominal). The power transformer T601
is provided with split input windings which are normally
connected in parallel for 115-volt operation, but which can
be connected in series for 230-volt operation.
The primary windings are marked 1, 2, 3, and 4, Terminals
1 and 3 are connected to one winding and terminals 2 and 4
are connected to the second winding. The ac input leads are
connected to terminals 1 and 4 for both 115-volt and 230-
®
To 115-v AC
To 230-v AC
Fig. 2-2. (al Transformer connection for operation from 103.5~
126.5 volt ac line; (b) connections for operation from 207-253
volt ae line.
As long as the ac power cord is connected to the ac line,
power is being applied to the power transformer T601, ac-
rectifier circuit, and graticule lights for all positions of the
POWER switch. Application of power to these circuit is re-
quired to provide battery-charger operation for the internal
batteries; the graticule lights provide visual indication that
these circuits are “on”. Power to the battery charger itself is
controlled by a Charger switch (see Fig. 2-1). If the switch
2-1

Preliminary Instructions — Type 321A
is set to LOW or HIGH, the ac rectifier is connected to the
battery charger circuit which, in turn, provides charging cur-
rent to the internal rechargeable batteries.
NOTE
If dry cells are used instead of rechargeable bat-
teries, then the Charger switch must be set to DRY
CELLS to disconnect the charger circuit. For further
information about battery operation, refer to the
topics titled “Battery Operation” and ‘'Battery
Charger" appearing in this section of the manual.
If the Type 321A is being operated exclusively from the
ac line and the internal batteries are removed, the Charger
switch can remain in the DRY CELLS position to disconnect
the charger circuit. If you prefer to completely turn off
all power to the Type 321A, set the POWER switch to
TRICKLE and either disconnect the power cord from the
ac line or turn off the power at a wall switch (or equiv-
alent}.
Battery Operation
Operation from the internal battery source can be accom-
plished by using:
1. Ten size D flashlight cells (approximately '/,-hour con-
tinuous operation, more with intermittent operation), or
Ey
Ten size D Alkaline cells such as Eveready E95, Burgess
AL-2, or Mallory MN-1300 (about 2'/; hours continuous
operation), or
wo
. Ten size D nickel-cadmium rechargeable cells (up to
about 5 hours continuous operation, depending on the
type used).
The nickel-cadmium cells are the most practical type where
considerable battery operation is planned.
To install the cells, first open the battery cover as illus-
trated in Fig, 2-3, Next, install the batteries by following
the procedure given in Fig. 2-4.
CAUTION
Be sure to observe cell polarity indicated on the
battery cover.
To turn on the Type 321A when operating from the internal
batteries, set the POWER switch to BATT ON. To turn off the
oscilloscope, set the POWER switch to one of the OFF posi-
tions—FULL or TRICKLE. These OFF positions disconnect
the batteries from the oscilloscope load {10-volt regulated
supply) so there is no battery drain. To charge the recharge-
able batteries, refer to the next topic titled “Battery Charger”.
Loosen thumb screw te unlock
cover, then pull cover forward to
remove.
Fig. 2-3. Removing the battery cover from the Type 321A Oscilloscope.

Preliminary Instructions — Type 321A
id
‘of the battery Medak Be sure
to observe cell polarity as. in-
dicated on the. cover.
Fig. 2-4, Procedure for installing the batteries.
Battery Charger
As mentioned previously, the battery charger is connected
to the internal batteries as long as the ac power cord is
connected to an ac power source and the Charger switch
{see Fig. 2-1) is set to HIGH or LOW. No charging occurs if
the Charger switch is set to DRY CELLS.
Table 2-1 summarizes the charging currents that can be
obtained by using various line voltages in combination with
various settings of the POWER and Charger switches. The
table shows the Type 321A wired for 115-volt nominal line
operation, If the oscilloscope is wired for 230-volt nominal
line operation, the charging currents will still be the same
but the ac line voltages will be twice the amount shown in
the table.
Use Table 2-1 as an aid in determining the proper posi-
tion for the POWER and Charger switches for the particular
brand or type of rechargeable batteries being used in the
Type 321A. After setting the switches to their proper posi-
tion, the line voltage can then be set to the charging rate
recommended by the manufacturer of the cells. An auto-
transformer having a rating of at least 1 ampere and
equipped with an rms-reading ac voltmeter can be used to
set the line voltage.
When using rechargeable batteries, sixteen hours of
charging at the full rated charging current recommended
by the manufacturers should be adequate to fully charge
the batteries. Excess charging may damage the batteries,
One methed for determining charge conditions of the bat-
teries is to set the POWER switch to BATT ON and then
measure the voltage across the battery terminals (see Fig,
2-4). A reading higher than 13 volts indicates that the
batteries are fully charged. A reading lower than 13 volts
indicates that more charging time is required.
As mentioned previously, if dry cells are installed in the
battery holder and the Type 321A is being operated from
the ac line, the Charger switch must be set to the DRY CELLS
position, This position disconnects the charging circuit from
the batteries.
TABLE 2-1
Charging Currents
POWER*| Charger Aproximate Charging
Switch | Switch Current in Ma
Position | Position | 103.5 v 109 v 115 v 121 v/126.5v
Ton |_tOW | 20. 2a | 7] 1 8
EXT ON |— ae eennlan ae
HIGH | 229630 [33 | 35
TRICKLE Low | 31 34 | 38 4] 44
| HIGH | 3437 aaa
it Low |” 166 [" 180 | 200220330”
HIGH |""290_| 320 | 360 380” “aio
"The BATT ON position is not included in the table because the
Type 321A should not be operated from the ac line and the
batteries at the same time, Reoson: Battery drain exceeds charg-
ing rote.
2-3

Preliminary Instructions — Type 321A
De Operation
Operation from an external de source is acomplished by
connecting the special pigtail-type de power cord in the
proper manner. For 11.5- to 20-volt operation, the black
(+] and white (—) leads are connected to the voltage
source; for 20- to 35-volt operation, the green (+) and white
{--) leads are connected to the voltage source. When the
connections to the external de voltage source are properly
made, the external de source is floating with respect to the
Type 321A chassis. Up to 600 volts difference is permissi-
ble, if necessary.
To turn on the Type 321A, set the POWER switch to EXT
ON. To turn off the oscilloscope, set the POWER switch to
‘one of the OFF positions—TRICKLE or FULL.
When operating from the external de source, the ac line
cord should be disconnected, That is, only one of the exter-
nal sources should be used rather than both at the same time.
2-4
NOTE
The internal battery charger circuit is disconnected
during external dc operation. Therefore, external
batteries (if used as the dc source) cannot be
charged by connecting the line cord to the ac line.
Also, an external de source cannot be used to
charge the internal batteries since the POWER
switch does not electrically connect the two
sources together.
LOW BATTERIES Light
The LOW BATTERIES light turns on when the following
conditions exist:
1. The POWER switch is set to BATT ON and the internal
batteries drop to 11.5 v (0.2 v) or lower.
2. The POWER switch is set to EXT ON and the external
source voltage is low enough to cause the Type 321A un-
regulated voltage to drop to about 11.5v or lower.