Tektronix 511 Instruction Manual page 54

are shunted across these circuits also.
The easiest way to make these adjustments
is to send a square wave through the attenuator
and observe the resulting waveshape on the o s ­
cilloscope itself. When the capacity and r e sis ­
tive dividers have the same ratio the square wave
is reproduced correctly. If the capacity divider
has a lower attenuation ratio than the resistive
divider a spike appears on the corners. If the
capacity divider has a higher attenuation, the
corners are rounded. To make these effects
more pronounced the square wave frequency
should be such that one cycle is from 4 to 20
times the time constant of the attenuator. In
the case of the Type 511A a frequency of 1000
cycles is satisfactory. The amplitude of the
square wave test signal should be adjustable
from 1 to 50 volts (peak-to-peak).
The Tektronix Type 104A and Type 105 Square
Wave Generators are suitable for this purpose.
If a Tektronix Oscilloscope is available, its
square wave calibrator may be used.
A procedure which has proven satisfactory is
as follows:
h Lay a metal sheet on top of the instrument
to simulate the presence of the case.
2. Apply a 50 v square wave to the Signal
Input connector, set the INPUT CHAN. SEL.
to VIA COND., the INPUT ATTENUATOR to
X2, and adjust C37 (left rear on attenuator).
3. Reduce the square wave amplitude to 10 v ,
move the INPUT CHAN. SEL. to 1 STAGE,
and adjust C42 (left on Input Chan. Sel.).
4. Move INPUT ATTEN. to X4, increase square
wave to 20 v, and adjust C34 (center rear on
attenuator).
5. Move INPUT ATTEN. to X8, increase square
wave to 40 v, and adjust C31 (right rear on
attenuator).
6. Reduce the square wave amplitude to 1 v,
move the INPUT CHAN. SEL. to 2 STAGES,
INPUT ATTEN. to X2, and adjust C44 (right
on input chan. sel.).
7. (S/N455 and up). Move square wave signal
from SIGNAL INPUT to the probe, apply a 5 v
signal, set INPUT ATTEN to XI, and adjust
P A G E 5 - 2
the probe compensating capacitor.
7. (S/N101-454).
SIGNAL INPUT TO ATTEN. 5X, apply a
2.5 v signal, set INPUT ATTEN. to XI, and
adjust C30 (between Input and Atten. 5X bind­
ing posts).
8. Move INPUT ATTEN. to X2 and adjust C38
(left front on attenuator), using a 10 v
(5 v, S/N 101-454) signal.
9. Move INPUT ATTEN. to X4 and adjust C35
(center front on attenuator), using a 25 v
(10 v, S/N-101-454) signal.
10. Move INPUT AJTTEN. to X8 and adjust C32
(right front on attenuator), using a 50 v
(25 v, S/N 101-454) signal.
ADJUSTMENT OF VERTICAL AMPLIFIER H.F.
RESPONSE
The video amplifier in the Type 511A employs
a four
adjusted at the factory for optimum transient
response, rather than flattest frequency re ­
sponse. This is done by observing the response
to a 1 me square wave having a^jrisetime of .03
microseconds or less. This test signal should
have squarest possible corners and a minimum
of overshoot so that the oscilloscope compensa­
tion adjustments are not inadvertently used to
correct for these deficiencies.
The Tektronix Type 104A and Type 105 Square
Wave Generators provide a suitable signal.
Since the image on the tube is the resultant
deflection of both sides of the push-pull ampli­
fiers, VI8 and VI9, the adjustment of the com ­
pensating coils is somewhat interdependent.
The factory procedure which gives the flattest
frequency response consistent with satisfactory
transient response is as follows:
1. Set all cores in the compensating coils for
minimum inductance.
2. Place INPUT CHAN. SEL. in 1 STAGE posi­
tion and set VERT. AMPL. ATTEN. for maxi­
mum gain.
3. Apply 1 me square wave of such amplitude that
about 2 to 3 cm deflection is obtained (INPUT
ATTENUATOR may be in any position).
T Y P E 5 1 1 - A D J U S T M E N T S
Move square signal from
terminal coupling network which is