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[[File:Tek 112 front.jpg|thumb|200px |right]]
{{Instrument Sidebar
|manufacturer=Tektronix
|model=112
|class=Amplifier
|series=
|summary=Differential amplifier
|image=Tek 112 front.jpg
|caption=Tek 112 front
|introduced=1949
|discontinued=(?)
|designers=
|manuals=
* [[Media:070-053.pdf|Tektronix 112 Manual]]
}}
The '''Tektronix 112''' is a DC-coupled differential amplifier [[introduced in 1949]].   
The '''Tektronix 112''' is a DC-coupled differential amplifier [[introduced in 1949]].   
The voltage gain can be set from 0.5 to 5000 V/V. 
The frequency response is DC to 2 MHz when the gain is set below 166, and DC to 1 MHz for gain settings greater than that.


The 112 is intended for use with the [[511]], [[512]], [[514]], and [[524]] oscilloscopes.
The 112 is intended for use with the [[511]], [[512]], [[514]], and [[524]] oscilloscopes.
The input impedance is 1 MΩ in parallel with 47 pF. The output impedance is 8000 Ω. 
 
{{BeginSpecs}}
{{Spec | Amplification    | 0.5 to 5000 V/V }}
{{Spec | Bandwidth        | DC to 2 MHz @ gain < 166; DC to 1 MHz above }}
{{Spec | Input impedance | 1 MΩ // 47 pF }}
{{Spec | Output impedance | 8 kΩ }}
{{EndSpecs}}
 
==Internals==
 
The amplifier's schematic and response are identical to that of a [[512|Tek 512]].
The amplifier's schematic and response are identical to that of a [[512|Tek 512]].


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The 112 has a differential output intended for directly driving the vertical deflection plates of a CRT.
The 112 has a differential output intended for directly driving the vertical deflection plates of a CRT.
The output terminals of the 112 are on the right side in the rear, so the 112 can sit to the left of an oscilloscope
The output terminals of the 112 are on the right side in the rear, so the 112 can sit to the left of an oscilloscope and short wires can connect the 112 to the oscilloscope's CRT.
and short wires can connect the 112 to the oscilloscope's CRT.
 
A two-position switch on the rear panel of the Type 112 controls the common-mode output voltage.
A two-position switch on the rear panel of the Type 112 controls the common-mode output voltage.
In one position, the common-mode output voltage is +150 V,
In one position, the common-mode output voltage is +150 V, which is the plate voltage of the [[6AG7]] tubes of the output amplifier.
which is the plate voltage of the [[6AG7]] tubes of the output amplifier.
In the other position, the common-mode output voltage is 0 V.
In the other position, the common-mode output voltage is 0 V.
The shifting of the common-mode output voltage 150 V downward is accomplished
 
by enabling a pair of 680 μA DC current sinks that cause a voltage drop on 220 kΩ series output resistors.
The shifting of the common-mode output voltage 150 V downward is accomplished by enabling a pair of 680 μA DC current sinks that cause a voltage drop on 220 kΩ series output resistors.
[[6CB6]] pentodes form the current sinks, with their cathodes tied to -150 V.
[[6CB6]] pentodes form the current sinks, with their cathodes tied to -150 V.
The 220 kΩ output resistors also provide short circuit protection.
The 220 kΩ output resistors also provide short circuit protection.
The Type 112 manual recommends 0 V for driving the CRT of the [[511]],
and +150 V for driving the CRT of the [[512]], [[513]], or [[514]].


==Manuals==
The Type 112 manual recommends 0 V for driving the CRT of the [[511]], and +150 V for driving the CRT of the [[512]], [[513]], or [[514]].
* [http://w140.com/tek_112.pdf Tektronix 112 Manual (PDF)]


==See Also==
==See Also==
* [[121]]
* [[121]]


==Photos==
==Prices==
* 1949: $495  (~ $6,300 in 2023 dollars)
 
==Pictures==
<gallery>
<gallery>
tek_112_18.jpg
tek_112_18.jpg
Line 44: Line 63:
tek_112_14.jpg|Underside of bottom deck, rear.
tek_112_14.jpg|Underside of bottom deck, rear.
tek_112_15.jpg|Underside of top deck.
tek_112_15.jpg|Underside of top deck.
tek_112_16.jpg
tek_112_16.jpg|Vibration-isolated front-end amplifier
tek_112_20.jpg
tek_112_20.jpg|Deflection sensitivity switch.
tek_112_3.jpg
tek_112_3.jpg|Top internal
tek_112_4.jpg
tek_112_4.jpg|Top front internal
tek_112_5.jpg
tek_112_5.jpg|Top rear internal
tek_112_6.jpg
tek_112_6.jpg
tek_112_7.jpg
tek_112_7.jpg
tek_112_8.jpg
tek_112_8.jpg|Left rear. Power supply tubes on the left: three [[5V4G]] rectifiers (one missing) and one [[6AS7]] triode series pass tube.
tek_112_9.jpg
tek_112_9.jpg|Rear of front panel has sockets for holding spare tubes.
tek_112_2.jpg
tek_112_2.jpg
tek_112_1.jpg
tek_112_1.jpg
Tek 112 ad - Electronics-1949-12.jpg | Tek 112 ad from Electronics, Dec 1949
</gallery>
</gallery>


==Components==
{{Parts|112}}


[[Category:Differential amplifiers]]
[[Category:Differential amplifiers]]
[[Category:Introduced in 1949]]

Latest revision as of 12:39, 9 February 2024

Tektronix 112
Differential amplifier
Tek 112 front

Produced from 1949 to (?)

Manuals
(All manuals in PDF format unless noted otherwise)
Manuals – Specifications – Links – Pictures

The Tektronix 112 is a DC-coupled differential amplifier introduced in 1949.

The 112 is intended for use with the 511, 512, 514, and 524 oscilloscopes.

Key Specifications

Amplification 0.5 to 5000 V/V
Bandwidth DC to 2 MHz @ gain < 166; DC to 1 MHz above
Input impedance 1 MΩ // 47 pF
Output impedance 8 kΩ

Internals

The amplifier's schematic and response are identical to that of a Tek 512.

The first stage is a differential amplifier using a pair of 5879 pentodes. Next is a differential amplifier using a pair of 12AU6 pentodes.

The 112 has a differential output intended for directly driving the vertical deflection plates of a CRT. The output terminals of the 112 are on the right side in the rear, so the 112 can sit to the left of an oscilloscope and short wires can connect the 112 to the oscilloscope's CRT.

A two-position switch on the rear panel of the Type 112 controls the common-mode output voltage. In one position, the common-mode output voltage is +150 V, which is the plate voltage of the 6AG7 tubes of the output amplifier. In the other position, the common-mode output voltage is 0 V.

The shifting of the common-mode output voltage 150 V downward is accomplished by enabling a pair of 680 μA DC current sinks that cause a voltage drop on 220 kΩ series output resistors. 6CB6 pentodes form the current sinks, with their cathodes tied to -150 V. The 220 kΩ output resistors also provide short circuit protection.

The Type 112 manual recommends 0 V for driving the CRT of the 511, and +150 V for driving the CRT of the 512, 513, or 514.

See Also

Prices

  • 1949: $495 (~ $6,300 in 2023 dollars)

Pictures

Components

Some Parts Used in the 112

Part Part Number(s) Class Description Used in
12AU6 154-0040-00 Vacuum Tube (Pentode) RF pentode 81 112 1L10 1L20 1L60 3L10 512 556 575 545 547 549 581 585 A B C G K H L ML M N O R S Z
5879 154-0055-00 Vacuum Tube (Pentode) sharp-cutoff pentode 112 512 D E Hickok 1825
6AG7 154-012 154-0012-00 Vacuum Tube (Pentode) 9 Watt power pentode 104 104A 105 112 511 511A 512 513 514 517 517A 524
6CB6A 154-0030-00 Vacuum Tube (Pentode) pentode 105 112 316 317 503 504 513 517 517A 541 535 545 63 2A63