Tektronix 516 series, Инструкция по эксплуатации

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Calibration — Type 5 1 6
Adjustment of B channel is done in the same manner as
outlined above. C503 is adjusted for instruments below
SN 570 while C520 and C521 are adjusted for instruments
above this serial number.
2 7 . Switched Amplifier Interelectrode Capacitance Com­
pensation.
When a signal with fast-rising portions is ap­
plied to one of the input channels, and that input channel is
“ turned off" by the action of the Switching Circuit, the grid-
to-plate capacitance of the Switched Amplifier in that chan­
nel tends to couple a part of the signal through to the
Output Amplifier. When this happens, the coupled-through
portions of the signal in the turned-off input channel appears
as spikes on the signal in the other channel. To counteract
this tendency, C450, C451, C550, and C551 must be adjusted
to compensate for the grid-to-plate capacitance of their re­
spective Switched Amplifier tubes.
To adjust C450 and C451, apply a 1-kHz square wave from
the Type 106 Square-Wave Generator to the A VERTICAL
input connector. Set the black TRIGGER SELECTOR control
to EXT. and apply an external triggering signal from the
square-wave generator to the TRIGGER INPUT connector.
Set both VOLTS/DIV. controls to .05. Set the MODE switch
to A ONLY and the TRIGGERING LEVEL and STABILITY
controls for a stable display and several cycles of the square-
wave signal. Set the amplitude control of the square-wave
generator so that the peak-to-peak amplitude of the dis­
played square waves is slightly greater than the diameter of
the face of the crt. Set the MODE switch to B ONLY. In­
spect the trace very carefully for small negative and positive
spikes along its length. Adjust C450 and C451 as necessary
to reduce the amplitude of these spikes, if any, as much as
possible. Try to adjust both capacitors approximately the
same amount in order to maintain the balance of the chan­
nel. When the adjustment is completed, both adjusting
screws should extend about the same distance above the
capacitor bodies.
TYPE 516
5 0 TERMINATION
Fig. 6 -1 1 . Connecting the Tektronix Type 106 Square-W ave Gener­
a to r to the Type 5 1 6 Oscilloscope fo r adjustm ent o f the D elay Line.
To adjust C550 and C551, apply the output of the square-
wave generator to the B VERTICAL input connector, and set
the MODE switch to A ONLY. Then adjust C550 and C551
in the manner described for C450 and C451 in the previous
paragraph.
These adjustments interact with the adjustment of the Delay
Line described in the following paragraphs. Therefore, when­
ever you have changed the setting of any of these capaci­
tors, you should check the adjustment of the Delay Line.
Delay Line and Vertical Amplifier High Fre­
quency Compensation
O f all the adjustments you may be called upon to perform
on the Type 516 Oscilloscope, the adjustment of the Delay
Line and the high-frequency compensation of the Vertical
Amplifier will be the most critical. This is due largely to the
interaction between the adjustments. There are 42 variable
capacitors and 2 variable inductors associated with the De­
lay Line, and 2 variable inductors and 4 variable capacitors
in the Vertical Amplifier, and all of the adjustments interact
to some degree.
Before making any of the adjustments decribed in this
section, read the instructions carefully so that you will be
sure of what is to be done. Study the photographs and il­
lustrations carefully in order to obtain a clear understanding
of the result of each adjustment. Attempts to adjust the
Delay Line without adequate preparation frequently lead to
a misadjustment more severe than the initial condition.
Displaying the Test Signal.
To determine whether the
Delay Line is in need of adjustment, and to make the neces­
sary adjustments, you will need to apply a square wave to
the oscilloscope and observe the waveform displayed on the
crt. The risetime of the square wave applied will affect the
accuracy of the tuning of the Delay Line; the shorter the rise­
time of the applied square wave, the greater will be the
ability to tune accurately. For this reason, the risetime of
the square wave applied should be kept as short as possible;
15 nanoseconds or less may be considered satisfactory for
most uses of the oscilloscope. Also, the waveform should be
free of overshoot and irregularities.
The Type 106 Square-Wave Generator which has a rise­
time of 1 nanosecond or less when connected as shown in
Fig. 6-11 is suitable for use in tuning the delay line of the
Type 516 oscilloscope. All tuning should be done on the
positive half-cycle of the waveform.
A square-wave frequency of about 450 kHz is optimum
for tuning the Type 516 Oscilloscope. This frequency per­
mits the broadest oscilloscope display while preventing the
appearance of reflected aberrations from the preceding rise
or fall of the waveform (these reflected aberrations can
appear at frequencies over 500 kHz).
To check the response of the Vertical Amplifier and De­
lay Line, apply the 450-kHz square wave to the A VERTI­
CAL input connector and set the front-panel controls of the
Type 516 as follows:
TIME BASE
TRIGGER SELECTOR AC
(red)
6-10