Tektronix Type 82 PLUG-IN Instruction Manual page 49

Adjust Channel A X10 GAIN control (see Fig. 5-2) so the
waveform is exactly two centimeters in amplitude. Discon-
nect the cable and the adapter.
19. Check for Microphonics (Both Channels)
This step checks for excessive ringing-type microphonics in
the nuvistors with the GAIN switch set to X10.
To make the check rotate the Stability control fully clock-
wise to free run the sweep. Ground the Input Connector,
or if the Type 82 has a serial number of 3000 or higher,
the GND position on the AC-DC-GND switch may be used.
After grounding the input tap lightly on the front panel
of the Type 82. Watch for microphonics on the crt screen.
Sustained microphonics should be less than one centimeter
Set the MODE switch to B ONLY and check for micro-
phonics as described in the previous paragraph.
20. * Channel B GRID CURRENT ZERO
Using a small screwdriver, short the center conductor of
the Channel B INPUT BNC connector to its outer conductor
(ground), If the trace shifts vertically, note the position of the
trace and continue with this step. However, if there is no
trace shift, unground the connector and go to the next step.
To cancel trace shift due to V233 grid current, first un-
ground the Channel B INPUT connector. Then, adjust the B
GRID CURRENT ZERO control (see Fig. 5-2} to position the
trace to the point noted at the beginning of this step.
To check on the accuracy of your adjustment, intermittent-
ly short the Channel B INPUT connector to ground. If there
is trace shift, carefully readjust the B GRID CURRENT ZERO
control until there is no trace shift.
If the trace shift cannot be eliminated by means of the
B GRID CURRENT ZERO control, replace V233. If V233 is
replaced, repeat steps 11, 16, 19 and this step before going
to the next step.
Allow at least 10 minutes warmup time for the
replaced tube to stabilize before repeating step
21. * Channel A GRID CURRENT
ZERO Adjustment
Set the MODE switch to A ONLY. Then, using a small
screwdriver, ground the Channel A INPUT connector. If the
trace shifts vertically, note the position of the trace and
continue with this step. If there is no trace shift, unground
the connector and proceed to the next step.
To cancel trace shift due to V133 grid current, first un-
ground the Channel A INPUT center conductor. Then, ad-
just the A GRID CURRENT ZERO control (see Fig. 5-2) to
Position the trace to the point noted at the beginning of
* On instruments SN 3000-up, ground the input connector by
setting AC-DC-GND to GND. Where the input does not have to
be grounded, return the switch fo DC.
Check on the accuracy of your adjustment by intermit-
tently shorting the Channel A INPUT connector to ground.
If there is trace shift, carefully readjust the A GRID CUR-
RENT ZERO control for no trace shift.
If the trace shift cannot be eliminated by adjusting the
A GRID CURRENT ZERO control, replace V133. If V133 is
replaced, repeat steps 10, 11, 15, 19 and this step before go-
ing to the next step.
22. Channel A X10 POSITION RANGE
Adjustment
First repeat step 15 to make sure the Channel A XI]
POSITION RANGE control is still in proper adjustment.
Slight readjustment of this control may be necessary due to
normal circuit drift. Be certain the Channel A VERTICAL
POSITION control is set to 0° (For an exact 0° setting, use
the voltmeter to obtain a reading of zero volts as described
Adjust Channel A X10 POSITION RANGE control to posi-
tion the trace to coincide with the center horizontal graticule
line. Set Channel A POLARITY switch to INVERT. The trace
should not shift more than -+1 centimeter from the center
Set the GAIN switch to X1 and the A POLARITY switch
to NORM. Trace shift should not be greater than -1
centimeter from the Type 82 distributed-amplifier electrical
center.
23. Channel B X10 POSITION RANGE
Adjustment
First, set the GAIN switch to X10 and the MODE switch to
B ONLY. Repeat step 16 to make sure Channel B X1 POSI-
TION RANGE control is still in proper adjustment. Be cer-
tain that the B VERTICAL POSITION control is set to exactly
0°. (For an exact 0° setting, use the voltmeter to obtain a
reading of zero volts as described in step 2.)
Adjust Channel B X10 POSITION RANGE control to make
the trace coincide with the center horizontal graticule line.
Set the Channel B POLARITY switch to INVERT. and check
the amount of trace shift. The trace should not shift more
than +1 centimeter from the center horizontal graticule
Set the GAIN switch to X1 and the B POLARITY switch to
NORM. The trace should not shift more than 1 centimeter
from the Type 82 distributed-amplifier electrical center.
24. Channel B Input Time Constant
Standardization and Attenuator
Compensation
This step is a combination procedure which describes a
method of adjusting the input capacitance of each channel
so the input time constant is the same for each position of
the V/CM switch. This permits a P6008 probe, when comp-
ensated using one setting of the V/CM switch, to be used