Calibration— Type M
TABLE 5-4
Square-Wave Response Check
Square-Wave Generator
O utput Frequency
Oscilloscope Time/Cm
Switch Setting
100 cps
5 Millisec
250 cps
2 Millisec
1 kc
.5 Millisec
2.5 kc
.2 Millisec
10 kc
50
fiSec
When the VOLTS/CM switch is set to each of its switch
positions, maintain approximately 3 centimeters of vertical
deflection by adjusting the Type 105 Amplitude control. In
addition, it will be necessary to make the following setup
changes as you proceed: Remove the 5XT attenuator when
the VOLTS/CM switch is set to the .5 position, and remove
both 50-ohm terminations when the VOLTS/CM switch is set
to the 5 position. These changes are necessary to obtain
sufficient signal drive as the VOLTS/CM switch is advanced
toward the 10 position.
Any marked departure from a flat-topped waveform
when applying a 100-cps square-wave signal could indicate
a defective protective network C5318 and R5318. If C5318
is open, for example, the tops of the waveform for all
positions of the VOLTS/CM switch will slope downward.
If trouble is suspected, you can usually verify your find
ings by comparing the waveform with those obtained on
the other channels.
If all the adjustments listed in the
last
column of Table
5-3 (step 15) are correct, and a 10-kc signal is applied,
an
optimum
flat-top
waveform
will
be
displayed
at each setting of the VOLTS/CM switch from .05 to 10.
However, if one or more of the adjustments are not made
correctly, the waveform will not have a flat top for those
switch positions utilizing the maladjusted attenuator net
work. To compensate or touch-up an attenuator, continue
to apply the 10-kc signal, set the VOLTS/CM switch to the
appropriate setting listed in the first column of Table 5-3,
and adjust the applicable capacitor listed in the last
column. The 47-pf Input Time Constant Standardizer is not
needed for this adjustment.
After completing the check for channel A, make the
same check for the other channels by repeating the pro
cedure. After completing the check for the last channel,
disconnect the signal from the input connector and turn off
the Type 105.
17. Channel A Output DC Level
In this step the channel A input connector is grounded
and the dc level at the "A ” SIGNAL OUT connector is
adjusted to zero or ground level, using channel B as a dc
voltmeter.
Match the levels by first setting the oscilloscope Time/
CM switch to .5 Millisec. Set the channel A VOLTS/CM
switch to .02 and the channel B VOLTS/CM switch to 2.
Set the A and B MODE switches to DC NORM. Set the
MODE switches for the remaining channels to OFF. Con
nect a short patch cord between the channel A input con
nector and ground. Use the A and B POSITION controls
to position the traces to coincide.
Connect another short patch cord between the “ A ”
SIGNAL OUT connector and the channel B input connector.
If the channel B trace is displaced from the A trace, care
fully adjust the OUTPUT DC LEVEL control until the channel
B trace is moved back as accurately as possible to coin
cide with the A trace. Disconnect the patch cord connected
between the A input connector and ground.
18. Check Gain of Channel A Signal Output Amplifier
Check the gain of the Channel A Signal Output Ampli
fier by applying a 20-millivolt signal from the oscilloscope
calibrator to the channel A input connector. The channel B
waveform should be at least one centimeter, peak-to-peak,
in amplitude.
Disconnect the signal and the patch cords.
19. High-Frequency Compensation
The adjustment procedure which follows describes a
method of checking and adjusting the M-Unit Output Am
plifier for optimum high-frequency response.
To check the response, first turn on the Type 107 Square-
Wave Generator (or equivalent). Remove the Plug-In Exten
sion, insert the M Unit directly into the oscilloscope plug-in
compartment, and tighten the Securing Rod.
Connect a 50-ohm cable directly to the Output con
nector on the Type 107. Connect the other end of the
cable through a 50-ohm termination to the channel A
input connector on the M Unit.
Set the channel B MODE switch to OFF and set the oscillo
scope Time/Cm switch to .1 /xSec. Set the Approximate
Frequency control on the Type 107 for an output of approxi
mately 450 kc, and adjust the Approximate Amplitude con
trol for a vertical deflection of three centimeters.
If the high-frequency compensating circuits in the M
Unit are in proper adjustment, the leading corner of the
waveform should be square without appreciable overshoot
or ringing, similar to the display shown in Fig. 5-4(a). How
ever, if there is any rolloff at the corner, shown accentuated
in Fig. 5-4(c), or overshoot (with or without ringing) as
shown in Fig. 5-4(d), the high-frequency compensating cir
cuits are in need of adjustment.
If adjustment is required, rotate the H.F. PEAKING control
fully clockwise. Adjust the slugs in L5363 and L5373 in
equal increments for a square-cornered waveshape, similar
to Fig. 5-4(b). Then adjust the H.F. PEAKING control slowly
counterclockwise to obtain an optimum square leading
corner, as shown in Fig. 5-4(a).
Set the VOLTS/CM switch for the other channels to .02,
and repeat the procedure for each channel. When checking
each channel, set the appropriate MODE switch to DC
NORM, and set the other MODE switches to OFF. If one or
more channels show waveforms which do not have an
optimum square corner, readjust L5363, L5373 and the
H.F. PEAKING control slightly to obtain the best com
promise.
20. Check Risetime (All Channels)
A risetime measurement of each channel will check the
accuracy of the adjustments made in steps 15 and 19. Make
® i
5-7
