| Indicator Unit - Bandpass determined by plug-ins |
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General Information
The Tektronix Type 561A Oscilloscope is essentially an indicator unit with provision for two of a number of
plug-in units. The plug-in unit in the right-hand opening controls the horizontal (X-axis) deflection, and the
plug-in unit in the left-hand opening controls the vertical (Y-axis) deflection. The plug-in units can be
selected from any of the Tektronix '2' Series or '3' Series groups to privide the desired oscilloscope
performance.
Bandpass, Risetime, Vertical Deflection Factors, Input Impedance, and Sweep Rates are determined by the
plug-in units used.
Cathode-Ray Tube
Type -- T561(rectangular ceramic-envelope).
Phosphor -- P32
Unblanking -- Deflection type, dc-coupled, with grid intensification.
Graticule -- Variable edge lighted "no parallax" internal graticule. Marked in 8 vertical and 10 horizontal
divisions with each major division divided into 5 minor divisions on centerline.
Accelerating potential -- 3.5 kv.
Usable viewing area -- 8 divisions vertical by 10 divisions horizontal.
Deflection plate sensitivities -- 18.5 to 20.5 volts per division vertical, and 17.5 to 19.3 volts per
division horizontal.
Calibrator
Waveform -- Square waves at the line frequency.
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Output voltage -- 0.2 millivolt to 100 volts, peak-to-peak, in 18 steps.
Accuracy -- Peak-to-peak amplitude within 3% of indicated voltage.
Risetime -- Typically 4 microseconds.
Power Supplies
Electronically regulated for stable operation with widely varying line voltages and loads.
Line voltage requirements -- 105 to 125 volts, or 210 to 250 volts, rms, 50 to 400 Hz, single-phase ac.
Fuse -- 2-amp slow-blowing type for 117 volts, 1-amp slow-blowing type for 234 volts.
ventilation
Convection air cooled. Thermal cutout interrupts instrument power in the event of overheating.
Construction
Aluminum-alloy chassis and 2-piece cabinet.
Photo-etched anodized panel, blue vinyl paint over textured aluminum on cabinet.
Dimensions -- Height 13½ inches, width 9¾ inches, and depth 21½ inches.
Weight -- 30½ pounds, indicator unit only.
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above excerpts from Tektronix Type 561A Instruction Manual
Cooling
The air must be able to flow freely around the instrument so that it may cool. Vacuum tubes should not be
operated with envelope temperatures above 150° C when the ambient temperature is at 25° C, or above
175° C when the ambient temperature is at 50° C. The Type 561A can operate in ambient temperatures
up to 50° C. If the instrument overheats, the thermal cutout will turn off the power.
Operation
Operation or the Tektronix Type 561A Oscilloscope with two plug-in units in place is much the same as that
of a conventional Tektronix oscilloscope with corresponding vertical and horizontal deflection systems. The
plug-in units take the place of the vertical and horizontal deflection systems in a conventional oscilloscope;
their outputs connect directly to the deflection plates of the cathode-ray tube. The plug-in units can be
selected to give the Type 561A Oscilloscope the degree and type of performance demanded of it by a particular
application.
The front and back panels of the Type 561A have controls or switches that affect the display; however,
the plug-in units determine the major characteristics of the display.
Front Panel
The POWER ON switch permits turning the instrument on or off.
The SCALE ILLUM. control permits adjustment of the brightness of the graticule markings.
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The FOCUS control permits proper trace or spot focus for most intensity values.
The ASTIGMATISM control works in conjunction with the FOCUS control, and improves the focus over the
entire crt display.
The INTENSITY control permits changing the crt display brightness.
The ALIGNMENT control permits electronically tilting the level of the crt trace to agree with the
horizontal graticule markings.
The 18-position CALIBRATOR switch determines the peak-to-peak amplitude of the signal at the CAL. OUT
connector. It also permits turning the CALIBRATOR off. The calibrator output is used to set the gain of the
amplifier plug-in units and to check the basic timing of the time-base units.
Display Combinations
The plug-in unit in the right-hand opening of the Type 561A controls the horizontal (X-axis) deflection of
the crt beam. The unit in the left-hand opening controls the vertical (Y-axis) deflection.
To obtain the conventional display of a horizontal sweep with vertical deflection by the input signal,
insert a time-base plug-in unit on the right and an amplifier unit on the left. If a vertical sweep is desired
with the input signal displayed horizontally, insert the time-base unit on the left and the amplifier unit on
the right. If an X-Y display is desired, insert amplifier type plug-in units in both plug-in openings.
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above excerpts from Tektronix Type 561A Instruction Manual
| Knobs |
| 366-113 | Knob, Small, Charcoal (INTENSITY) |
| 366-113 | Knob, Small, Charcoal (FOCUS) |
| 366-117 | Knob, Large, Carcoal (CALIBRATION) |
| 366-113 | Knob, Small, Charcoal (SCALE ILLUM) |
| Pots/Switches |
| SW601 | 260-014 | Toggle Switch (Power ON) |
| R833 | 311-314 | 2 meg (Intensity) |
| R84 | 311-313 | 5 meg (Focus) |
| SW870 | 260-253 | Rotary (CALIBRATOR) |
| R601 | 311-055 | 50 ohm Var. (Scale Illum.) |
| Tubes |
| V609 | 154-291 | OG3 |
| V627 | 154-307 | 7233 |
| V634 | 154-187 | 6DJ8 |
| V654 | 154-022 | 6AU6 |
| V667 | 154-020 | 6AS7G |
| V674 | 154-022 | 6AU6 |
| V800 | 154-167 | 6CZ5 |
| V814 | 154-046 | 12BH7 |
| V822 | 154-051 | 5642 |
| V832 | 154-051 | 5642 |
| V859 | 154-400 | T5610-31-1 CRT P31 Phosphor (T561) |
| V884 | 154-278 | 6BL8 |
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