Tektronix TYPE Z PLIG-IN Instruction Manual Download Page 30

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Calibration — Type Z

five half cycle of the waveform by using the + Internal

position of the Triggering Mode switch. Adjust L7645, L8645,

L7632,  and  L8632  to  obtain  the  sharpest  negative  leading
corner  on  the  displayed  waveform  without  introducing  any
overshoot  (see  Fig.  5-7).  Adjust  each  pair  of  variable  in
ductors  (for  example,  L7645  and  L8645)  in  equal  increments
so  the  slugs  are  positioned  the  same  depth  in  the  coil  forms.

Disconnect the signal from the B input connector and

apply it to the A input connector. Set the Mode switch
to A O N LY. Set the oscilloscope Trigger Slope switch to

— Internal to display the positive half cycle of the w ave

form. Check to see if the leading corner of the positive
going waveform is as square as possible without overshoot.

If  it  is  not,  adjust  the  coil  slugs  for  a  compromise  between
the  best  display  obtained  with  signal  applied  to  the  B
input  connector  and  that  obtained  when  connected  to  the
A  input  connector.  The  compromise  setting  assures  that

the best possible high-frequency differential operation will be
attained.

Disconnect the square-wave generator cable and the

termination.

C A L . 1

C A L . 2

C A L . 3

C A L . 5

C A L . 4

F ig , 5 - 8 . Top v ie w of the Z U n it sh o w in g lo catio n of step 1 7 test

p o in ts a n d in te rn a l a d ju stm en ts.

16. Bandwidth Measurement

Apply a 50-kc sine-wave from the Type 190A Constant-

Amplitude Signal Generator (or equivalent) to B input
connector. Set the oscilloscope Time/cm switch to the .1

millisec position and free run the sweep. Adjust the gen
erator amplitude control so that the signal produces exactly

28 mm (2.8 cm) of deflection on the crt. Center the display
vertically on the screen.

Increase the sine-wave generator frequency to 13 me,

keeping the generator output level constant. (The Type
190A Generator maintains a constant-amplitude signal auto
matically.)

After the generator frequency has been increased to

13 me, (3 db point), there should be at least 20 mm (2 cm)

of deflection.

If another type of Tektronix oscilloscope is being used

with the Z Unit to make a bandwidth check, consult the
Specifications section of this manual for the upper frequency

limit. That is the frequency at which 20 mm of deflection

or  more  should  be  obtained.  For  instance,  if  a  Type  535A
Oscilloscope  is  used  in  conjunction  with  the  Z  Unit,  20  mm
or  more  should  be  obtained  with  the  sine-wave  generator
set  at  10  me.

Disconnect the generator from the B input connector

and  apply  the  signal  to  the  A  input  connector.  Set  the
Mode  switch  to  A  O N LY  and  repeat  this  step.  Disconnect
the  sine-wave  generator.

17. Precision Voltage Adjustments

Remove the Z Unit and connect an EP54 plug-in extension

between  the  unit  and  oscilloscope.  Set  the  COMPARISON
VO LTA G E  Polarity  switch  to  +  .  Make  certain  the  CO M
PARISON  V O LTAG E  Range  switch  is  set  to  100  V.  Before
proceeding  with  this  step,  be  sure  the  regulated  power
supply  voltages  measured  in  the  oscilloscope  are  within
specifications  as  noted  in  the  preliminary  calibration  in
structions.  Refer  to  Fig.  5-8  for  locations  of  all  test  points
and  internal  adjustments  given  in  this  step.

(a) Adjust CAL. 1:

Set the

precision voltmeter for

— 107.70 volts and connect it between Test Point A and

ground. Adjust CAL. 1 (R8674) for a null reading on the

meter.

(b) Adjust CAL. 2:

Set the

precision voltmeter for

+ 107.70 volts. Place the COMPARISON V O LTAG E Polar

ity switch in the — position. Adjust CAL. 2 (R7671) for a
null reading on the meter.

N O TE

W hen  adjusting  C A L.  1  and  C AL.  2  w irew ound
controls,  it  is  more  im portant  that  the  voltage
readings  be  id e n tical,  than  that  they  be  e xa ctly

1 0 7.7 volts. For instance, readings of — 1 0 7 .9 0

and

+ 1 0 7 .9 5 are better than — 1 0 7 .7 0 and

+ 1 0 7 .8 5 . Keep the two vo ltag e readings within

the range o f 107.3 to 108.1 volts, how ever.

+ 107.7 volts, connect it between Test Point B and Ground.

Set the COMPARISON V O LTAG E Polarity switch to the

+ position. Adjust CAL. 3 (R7681) for a null indication on

the meter. (If CAL. 1 and CAL 2 adjustments are set at

107.9 or any other voltage reading within limitations given

in step 17b, then CAL. 3 should set at the same voltage).

(d) Adjust CAL. 4: