| Bandwidth : DC to 300 kHz |
| Sensitivity : 1 mV/div to 20 V/div |
| Risetime : 1 µsec |
| Input Impedance : 1 MegΩ ,47 pf |
|
 |
 |
 |
The Type 2A63 Differential Amplifier module is designed for use with Tektronix Type 560-Series
Oscilloscopes. It has a bandpass of dc to 300 kc or greater and a differential rejection ratio of
approximately 50 to 1 or better, depending upon frequency and sensitivity (Rejection ratios as high as
2000 to 1 can be obtained through the use of two Tektronix Type P6023 attenuator probes). Sensitivity is
variable in 14 calibrated steps from 1 millivolt to 20 volts per division of deflection, and is continuously
variable (uncalibrated) between steps and up to 50 volts per division. Accuracy is within 3% of each of the
calibrated steps. In addition to differential operation, the module can also be used for single-ended operation. The input impedance at both inputs is one megohm paralleled by 47 picofarads. Maximum allowable signal voltage at the INPUT connectors is 600 volts (dc plus peak ac).
A Type 2A63 module can be used with a Type 2A60 or Type 3A75 module, or another Type 2A63, in the same
Type 560 series Oscilloscope to measure the phase relationship between two sine waves. Phase measurements
accurate to within 1° at 50 kc can be made with two properly calibrated Type 2A63 modules.
above excerpts from Tektronix Type 2A63 Instruction Manual
Throughout the instructions that follow, it is assumed, unless otherwise noted, that the Type 2A63 module is
inserted in the Y-axis opening ot a Type 560-Series Oscilloscope, thereby providing vertical deflection of the
oscilloscope trace. If the module is inserted in the X-axis opening of the oscilloscope, it will provide
horizontal deflection and the instructions must be interpreted accordingly, It is further assumed throughout
the discussion that there is a time-base module in the X-axis opening of the oscilloscope.
Signal Connections
When a single signal input is used with the Type 2A63 module, it may be applied to either the +INPUT connector
or the -INPUT connector. If the signal is connected to the +INPUT connector, the -INPUT AC-DC-GND switch should
be placed in the GND position and the +INPUT AC-DC-GND switch should be placed in the AC or DC position, depending
upon the type of coupling desired. If the signal is connected to the -INPUT connector, the +INPUT AC-DC-GND switch
should be placed in the GND position and the -INPUT AC-DC-GND switch should be placed in the AC or DC position.
If the signal is applied to the -INPUT connector, the display on the oscilloscope screen will be opposite in
polarity to a normal presentation. Conventionally, a normal display places the more positive portions of a
waveform in the vertical channel toward the top of the screen and the more positive portions of a waveform in the
horizontal channel toward the right side of the screen.
When it is desired to display the difference between two signals, one signal is connected to each INPUT
connector and both AC-DC-GND switches are placed in either the AC or DC position. In this mode of operation, the
two signals are subtracted from each other algebraically, and the difference is displayed as a single trace on the
oscilloscope screen. This is called the differential mode of operation. It permits you to eliminate signals which
are common to both inputs and to observe a waveform which is peculiar to one.
Use of the differential mode of operation is limited to signals of about ± 5 volts maximum at the input
to the first amplifier stage of the module. For this reason, the common mode signal at the INPUT connectors should
be limited to about ± 5 volts when the VOLTS/DIV. switch is set at any position from 1 mVOLTS through .2 VOLTS
and to about ± 50 volts when the VOLTS/DIV. switch is set at .5, 1, or 2 VOLTS. In the 5, 10, and 20 VOLTS
positions of the VOLTS/DIV. switch, the common-mode signal at the INPUT connectors may be as high
as ± 200 volts.
Displaying a Signal
To display a signal with the Type 2A63 module, proceed as follows:
1. Connect the signal to one or both INPUT connectors.
2. Establish a common ground between the oscilloscope and the signal source. This can be done by connecting the
ground clip on a Textronix attenuator probe to signal ground.
3. Adjust the time-base controls to obtain a stable display.
4. Set the VOLTS/DIV. switch and the POSITION control so that the signal is placed as desired on the graticule.
In general, if you are interested only in the ac component of the signal, you should set the appropriate AC-DC-GND
switch to AC; if you are interested in the dc level of the signal, you should set the appropriate AC-DC-GND switch
to DC.
An exception to this is in observing low-frequency signals, When the AC-DC-GND switch is in the AC position, and
the AC STABILIZED switch is in the OFF position, the lower bandpass limit (3-db point) of the module is
about 1.5 Hz. Therefore, when displaying signals with frequency components of less than about 2 Hz (0.2 Hz when
using a 10X attenuator probe), the best response will be obtained with the AC-DC-GND switch in the DC position.
When looking at ac signals of very small amplitude (less than about 10 millivolts), you may wish to use the
AC STABILIZED switch to eliminate dc drift in the oscilloscope trace. Placing this switch in the ON position
introduces ac coupling into the amplifier whenever the VOLTS/DIV. switch is in one of its five most sensitive
positions (1 mVOLTS through 20 mVOLTS). This prevents small dc drift conditions in the Input Amplifier of the
module from causing trace shift on the screen. When the VOLTS/DIV. switch is at 1 mVOLTS and the AC STABILIZED
switch is ON, the lower bandpass limit (3-db point) of the module is about 10 Hz.
Note that the small neon lamp to the left of the AC STABILIZED switch lights when either AC-DC-GND switch is in
the DC position while the AC STABILIZED switch is ON. This is to warn the operator that the amplifier is ac coupled
when the VOLTS/DIV. switch is in one of its five most sensitive positions, even though the AC-DC-GND switch is in
the DC position. (The light can be ignored if the VOLTS/DIV. switch is not in one of these positions.) If you wish
to measure dc levels in one of the five most sensitive positions of the VOLTS/DIV. switch, you must set the
AC STABILIZED switch to OFF.
above excerpts from Tektronix Type 2A63 Instruction Manual
| Knobs |
| 366-113 | Knob, Small Charcoal (POSITION) |
| 366-113 | Knob, Small Charcoal (DC BAL) |
| 366-038 | Knob, Small Red, 1/8 hole part way (VARIABLE) |
| 366-144 | Knob, Large Charcoal, 17/64 hole thru (VOLTS/DIV) |
| Pots/Switches |
| R436 | 311-240 | 200 ohm var (DC BALANCE) |
| R479 | 311-228 | 2 x 10K 2W var (POSITION) |
| R497 | 311-221 | 2K var. (GAIN ADJ) |
| R498 | 311-189 | 2K var (VARIABLE) |
| SW400/SW410 | 260-450 | Slide Sw (AC-GND-DC) |
| SW404 | | Rotary (VOLTS/DIV) |
| SW408 | 260-447 | Slide Sw (AC STABILIZED) |
| Tubes |
| V424 | | 6DJ8 (checked) |
| V484 | | 6CB6 |
| V494 | | 6CB6 |
| V503 | | 6CB6 |
|
