Controls, Connectors, and Indicators—2445 Operators
VERTICAL
Refer to Figure 3-2 for location of items 10 through 17.
® CH 1 OR X and CH 2 Input Connectors—Provide
for application of external signals to the inputs of
Channel 1 and Channel 2 vertical attenuators. A
signal applied to the CH 1 OR X connector provides
the horizontal deflection for an X-Y display. Any
one or all of the channels (including Channel 1)
may supply the signal for the X-Y display vertical
deflection. These connectors each include a coding
ring contact that activates the scale-factor-switching
circuitry whenever a scale-factor-switching probe
is connected. The internal circuitry recognizes
Tektronix attenuation-coded probes.
( lj) Input Coupling Switches and Indicators—Select the
method of coupling input signals to the Channel 1
and Channel 2 vertical attenuators and indicate the
selection made. If the Channel 1 and Channel 2 input
signals are both AC coupled and if both input cou
pling switches are pushed up together, the instrument
automatically performs a dc balance of Channel 1
and Channel 2 vertical circuitry.
1 M12 AC—Input signal is capacitively coupled to
the vertical attenuator. The dc component of the
input signal is blocked. The low-frequency limit
(—3 dB point) is 10 Hz or less when using either
a IX probe or a coaxial cable and is 1 Hz or less
when using a properly compensated 10X probe.
1 M12 GND—The input of the vertical amplifier
is grounded to provide a zero (ground) reference-
voltage display. Input resistance is 1 M12 to ground.
This position of the switch allows precharging of
the input-coupling capacitor to prevent a sudden
shift of the trace if AC input coupling is selected
later.
1 M12 DC—All frequency components of the input
signal are coupled to the vertical attenuator. Input
resistance is 1 M fl to ground.
1 Mf2 GND—In this position, the switch operates
exactly the same as previously described.
50 12 DC—All frequency components of the input
signal are coupled to the vertical attenuator, with
the input terminated by 50 12 to ground. If exces
sive signal is applied to either the CH 1 or the
CH 2 input connector while 50 12 DC input
coupling is selected, input coupling will revert to
1 M12 GND and a crt readout will indicate the
overloaded condition. Moving the input coupling
switch of the affected channel removes the over
load message. While power is off, coupling is at
1 M12 GND.
(T
2
) Channel 1 and Channel 2 VOLTS/DIV Switches—
Select vertical deflection factor settings in a 1-2-5
sequence with 11 positions. The VAR control must
be in the detent (fully clockwise) position to obtain
a calibrated deflection factor. Basic deflection factors
are from 2 mV per division to 5 V per division.
Deflection factors shown in the crt readout reflect
actual deflection factors in use when Tektronix
attenuation-coded probes are connected to the
inputs.
(T?) VAR Controls—Provide continuously variable, un
calibrated deflection factors between the calibrated
settings of the VOLTS/DIV switches. These controls
vary the deflection factors from calibrated (fully
clockwise detent position) to at least 2.5 times the
calibrated deflection factor (fully counterclockwise
position). When out of the calibrated detent, a greater
than (> ) sign appears in front of the associated
VOLTS/DIV readout display.
Figure 3-2. Vertical controls and CH 1 OR X and CH 2 connectors.
3-2
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