Tektronix 212 User manual

COMMITTED TO EXCELLENCE
OPERATORS MANUAL
First Printing NOV 1972
Revised 1981
Re-Typeset NOV 2021
212
OSCILLOSCOPE

TABLE OF CONTENTS
Page
Introduction 1
Safety Considerations 1
Controls and Connectors 1
Operating Power Information 6
General Operating Information 11
Operator’s Adjustments 21
Applications 24
Copyright © 1972 Tektronix, Inc. All rights reserved.
Contents of this publication may not be reproduced in any form
without the written permission of Tektronix. Inc.
Products of Tektronix, Inc. and its subsidiaries are covered by U.S.
and foreign patents and/or pending patents.
TEKTRONIX, TEK, SCOPE-MOBILE, and are registered
trademarks of Tektronix, lnc. TELEQUIPMENT is a registered
trademark of Tektronix U.K. Limited.
Printed in U.S.A. Specification and price change privileges
are reserved.
Tektronix, Inc. • P. O. Box 500 • Beaverton, Oregon 97077
Typeset by Jared Cabot - 2021/11
070-1375-00 212 REV D MAR 1981 1172

212 OSCILLOSCOPE
INTRODUCTION
The 212 Oscilloscope is a dual-channel portable oscilloscope
using all solid state and integrated circuitry (except the CRT). The
small size of the 212 makes it an extremely portable oscilloscope
for on-location maintenance in many fields of application.
SAFETY CONSIDERATIONS
When battery operated, store the AC plug in the
insulated compartment. The RFI circuitry connected
between the instrument common and the AC power
plug can cause small amounts of current from an
elevated reference to be present on the AC power
plug, imposing a possible shock hazard.
CONTROLS AND CONNECTORS
Controls and connectors necessary for operation of the 212
(with the exception of the POWER (BATTERY) indicator on the front
panel) are located on the right side of the instrument. To make full
use of the capabilities of this instrument, the operator should be
familiar with the function and use of each control and connector. A
brief description of each control and connector, along with some of
the more important instrument specifications, are given here.
1
CAUTION
212 Operators Handbook

1. POWER (BATTERY) Indicator - red light (on front panel) to indicate
when the instrument is on. When light extinguishes, battery charge
is low and about 10 minutes of operating life remain.
2.
&
3.
VOLTS/DIV - selects vertical deflection factor (vertical VARiable
control must be in CAL position for indicated deflection).
Calibrated position accuracy within 5%.
Vertical system bandwidth;
1 mV/div, 100 kHz; 2 mV/div, 200 kHz; 5 mV/div, 400 kHz;
10 mV/div to 50 V/div, 500 kHz.
4.
&
5.
INPUT COUPLING - selects the method used to couple the channel
input signal to the vertical amplifier system.
AC - DC component of input signal is blocked. Low frequency limit
(-3 dB point) is approximately 2 Hz.
2212 Operators Handbook

GND - vertical amplifier input circuit is grounded. The applied input
signal is connected to ground through a large resistor to provide a
pre-charge path for the AC input coupling capacitor.
DC - all components of the input signal are passed to the vertical
amplifier system.
6.
&
7.
STEP ATTEN BALance - a screwdriver adjustment to balance the
vertical amplifier system for minimum trace shift when switching
deflection factors.
8.
&
9.
Vertical POSition - controls the vertical position of the appropriate
trace. OFF detent turns the channel off.
10.
&
11.
VOLTS/DIV VARiable - provides a continuously variable deflection
factor between the calibrated settings of the VOLTS/DIV switch for
the appropriate vertical channel. Extends the maximum deflection
factor to at least 125 volts/div.
12. VERTical GAIN - screwdriver adjustment to set the gain of the
vertical amplifier system.
13. AUTO PRESET - screwdriver adjustment to set the AUTO PRESET
trigger point for automatic trigger operation.
14. Trigger SOURCE - selects the source of the trigger signal.
COMP - the sweep is triggered from a DC coupled sample of the
vertical deflection signal after the vertical switching.
CH 2 - the sweep is triggered from an AC coupled sample of the
vertical deflection signal before the vertical switching and only from
Channel 2.
EXT - the sweep is triggered from the DC coupled signal applied to
the EXT TRIG banana jack.
3212 Operators Handbook

15. LEVEL/SLOPE - selects the amplitude point and the slope of a
trigger signal on which the sweep is triggered. When the indicator
dot is to the left of center, the sweep is triggered on the positive-
going slope of the trigger signal; to the right of center, on the
negative-going slope. When the LEVEL/SLOPE control is set to the
AUTO PRESET detent, the sweep is automatically triggered at a
preset level on the positive-going slope. Stable triggering requires
a minimum of 0.2 division internal signal or 1.0 volt external signal
amplitude.
16. INTENSITY - controls brightness of CRT display.
4212 Operators Handbook

17. SWP CAL - screwdriver adjustment to provide calibrated sweep
timing.
18. POWER - controls power to the instrument. Does not interrupt
charging current to the internal batteries when the instrument is
connected to an AC line voltage.
19. FOCUS - screwdriver adjustment to obtain a well-defined display.
20. HORIZ MAG - provides continuously variable sweep magnification
to a minimum of approximately five times the sweep rate indicated
by the SEC/DIV switch.
21. HORIZontal GAIN - screwdriver adjustment to set the basic gain of
the horizontal amplifier system.
22. Horizontal POSition - controls the horizontal position of the trace.
23. SEC/DIV - selects horizontal sweep rate (horizontal VAR must be in
CAL position for indicated sweep rate). Calibrated sweep rate
accuracy within 5%.-X-Y position allows for X-Y operation with CH 2
supplying the vertical deflection and CH1 the horizontal deflection.
24. EXT TRIG - banana jack for input of an external trigger signal.
25. COMMON - banana jack to establish common ground between the
212 and the external signal source or equipment under test.
5212 Operators Handbook

OPERATING POWER INFORMATION
Internal Battery Operation
The 212 is designed primarily for operation from the internal
rechargeable batteries. The operating time provided from the
internal batteries depends upon trace intensity, and battery charge
and discharge temperature. Typical operating time from fully
charged batteries at maximum trace intensity when charged and
operated at +20°C to +30°C (+68°F to +86°F) is 4.5 hours. Longest
operating time is provided at lower trace intensity.
The POWER (BATTERY) indicator provides an indication of the
operating power. When the light extinguishes not more than 10
minutes of instrument operating power remains. The 212
possesses an automatic battery protection circuit to prevent
excessive discharge and the resulting battery damage if the
instrument is operated below the battery charge level of
approximately 10 volts.
Battery Charging
The charging characteristics of the nickel-cadmium (Ni-Cd) cells
used in the 212 vary with the temperature at which they are
charged. Batteries charged at about +20°C to +30°C (+68°F to
+86°F) will deliver more energy than when the same batteries are
charged at a higher or lower temperature.
6212 Operators Handbook

To charge the batteries, connect the instrument to an AC line
and set the POWER switch to the OFF position. Allow at least 16
hours for the batteries to reach full charge. For longest operating
life of the batteries, increase the charge time of the instrument to at
least 24 hours once a month. This procedure balances the charge
on all the cells in the battery and reduces the possibility of any
individual cell becoming reverse charged.
The nickel-cadmium cells will self-discharge when the
instrument is stored and not used for extended periods of time. The
rate at which this self-discharge occurs is dependent upon the
storage temperature and humidity. If the 212 is to be stored for
extended periods, particularly at either high ambient temperature or
high humidity, it is recommended that the batteries be run through a
full charge cycle (16 hours) about every two weeks, or that the
instrument be left connected to the AC line.
Typical Charge Capacity (reference to charge/discharge at
+20°C to +30°C):
CHARGE
TEMPERATURE
OPERATING TEMPERATURE
-15oC
(+5oF)
+20oC to +30oC
(+68oF to +86oF)
+55oC
(+131oF)
0oC (+32oF) 40% 60% 50%
+20oC to +30oC
(+68oF to +86oF) 65% 100% 85%
40oC (+104oF) 40% 65% 55%
7212 Operators Handbook

AC Operation
Due to the capacitive line input circuit, sudden voltage
changes may cause damaging input current transients. Avoid
operating this instrument from square-wave inverter supplies,
or other sources that produce large voltage transients.
If the internal batteries of the 212 become discharged to the
minimum operating level, continued operation can be obtained by
connecting the instrument to an AC power source. Due to the
circuitry connected with the internal battery charger, the AC power
line voltage must be at least 110 volts for operation in this manner.
Also, when operated with fully-charged batteries from an AC line
below about 110 volts and at a maximum trace intensity, the internal
batteries discharge slowly. Approximately 36 hours of continuous
operation can be obtained with fully charged batteries at maximum
intensity and a 104-volt line. The internal batteries cannot be
recharged while the instrument is being operated from the AC line.
If the instrument is to be operated on a power line other than
110 to 126 V AC, 58 to 62 Hz, refer to Option Information.
8
CAUTION
212 Operators Handbook