Tektronix TU-7 Instruction Manual Download Page 5

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SECTION 1

CHARACTERISTICS

Genera! Description

The Type TU-7 Piug-ln Test Unit is a versatile single-unit

calibration aid for use with all Tektronix 530-, 540-, or 550-

Series  Oscilloscopes  using  1-series  or  letter-series  vertical
plug-in  units.  The  Type  TU-7  is  the  only  plug-in  unit  re
quired  for  calibrating  the  oscilloscope.*  An  input  connector
on  the  front  panel  of  the  Type  TU-7  permits  application  of
various  external  signals  for  use  in  the  calibration  procedure.
The  self-contained  unit  also  generates  fast-rise  pufses  for

checking risetime and adjusting transient response of the
oscilloscope vertical amplifier.

The Type TU-7 permits checking the regulation limits of

the power supplies. In addition, the unit provides a quick

check of the oscilloscope alternate sync pulse and chopped
blanking circuitry. For oscilloscopes capable of displaying

two time-base signals alternately, the Type TU-7 checks the

ability of the alternate-sweep switching circuitry to lock

the channels of a dual-trace plug-in unit to the time bases

of the oscilloscope.

ELECTRICAL

TEST FUNCTION SWITCH POSITIONS

LOW LOAD, HIGH LOAD

These two switch positions permit the oscilloscope low-

voltage  power  supplies  to  be  loaded  from  minimum  to
maximum.  External  signals  applied  through  the  EXT  INPUT
connector  on  the  front  panel  of  the  unit  will  be  ac-coupled
to  the  oscilloscope  vertical  amplifier  to  produce  a  normal
display.  Maximum  vertical  sensitivity  of  the  Type  TU-7/
oscilloscope  combination  is  about  0.5volt/cm  when  the
VARIABLE  control  is  set  fully  clockwise.

GAIN SET

Permits setting the gain of the oscilloscope vertical ampli

fier with a 100-volt calibrator signal applied to the EXT

INPUT connector. The 250-to-l fixed ratio of this position

attenuates  the  100-volt  signal  to  0.4  volt  which  produces
4 cm  of  vertical  deflection  on  the  crt  when  the  oscilloscope
vertical  amplifier  gain  adjustment  has  been  accurately  set.

COMMON MODE

Checks common-mode rejection ratio and dc balance of

the oscilloscope vertical amplifier.

ALTERNATE

Checks operation of the alternate-mode synchronizing

circuits in the oscilloscope. Also permits checking for proper

sweep slaving in oscilloscopes having two time bases that
can be displayed alternately. Any external signal applied

* A s in e -w a v e b a n d p a s s check o f th e system c a n n o t b e m a d e b y

a p p ly in g a n e x te rn a l h ig h -fre q u e n c y sin e w a v e th ro u g h th e T yp e
TU -7 .

to the EXT INPUT connector is attenuated approximately

1000 times by an internal attenuation network.

CHOPPED

Checks oscilloscope for proper operation in the chopped

mode. Free-running rate of the dual-trace switching multi

vibrator is approximately lOOkc. Any external signal ap

plied to the EXT INPUT connector is attenuated approxi
mately 1000 times by the internal attenuation network.

+ PULSE, -PULSE

In these two switch positions a fast-rise 'square wave

with a risetime of 3 nsec {3 X 10~9 sec) is applied to the

oscilloscope vertical deflection system. Maximum amplitude

of  the  pulse  display  for  either  +   or  —  polarity  is  approxi
mately  6 cm  with  the  AMPLITUDE  control  set  fully  clock
wise.  Minimum  amplitude  is  approximately  2 cm.

Other Controls and Connectors

REPETITION RATE

Three-position switch to select the approximate pulse

repetition rate of the Pulse Generator circuit: LOW —
5 kc, MED — 120 kc, HIGH — 600 kc.

AMPLITUDE

Adjusts amplitude of the pulse applied to the oscilloscope

vertical amplifier when the TEST FUNCTION switch is set

to + PULSE or — PULSE.

VARIABLE

Controls amplitude of the signal applied through the

EXT INPUT connector when the TEST FUNCTION switch is

set to LOW LOAD or HIGH LOAD. The minimum deflec