112: Difference between revisions

From TekWiki
Jump to navigation Jump to search
No edit summary
No edit summary
(18 intermediate revisions by 2 users not shown)
Line 1: Line 1:
The Tektronix 112 is a DC-coupled differential amplifier [[introduced in 1955]].   
[[File:Tek 112 front.jpg|thumb|200px |right]]
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 voltage gain can be set from 0.5 to 5000 V/V.   
The frequency response is DC to 2MHz when the gain is set
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.  
below 166, and DC to 1MHz for gain settings greater than that.
The 121 is intended for use with the
[[511]], [[512]], [[514]], and [[524]] oscilloscopes.
The input impedance is 1 megohm in parallel with 47 pF.
The output impedance is 8000 ohms.  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
The 112 is intended for use with the [[511]], [[512]], [[514]], and [[524]] oscilloscopes.
[[5879]] pentodesNext is a differential amplifier using
The input impedance is 1 MΩ in parallel with 47 pF. The output impedance is 8000 Ω.   
a pair of [[12AU6]] pentodes.
The amplifier's schematic and response are identical to that of a [[512|Tek 512]].


The 112 has an unusual output coupling stage
The first stage is a differential amplifier using a pair of [[5879]] pentodes.   
It provides output short circuit protection and
Next is a differential amplifier using a pair of [[12AU6]] pentodes.   
shifts the common-mode DC level of the differential output to 0V.
The plate voltage of the final gain stage
(just before the output coupling stage) is about +150V.   
When enabled,
the output coupling stage is a a pair of constant current sinks.
It uses [[6CB6]] pentodes for this.   
This shunt current causes a constant voltage drop
across output resistors,
resulting in 0V at the output. 
The cathodes of the output coupling stage are
supplied by the -150V rail,
allowing them to operate as proper current sources
when their plates are at 0V.


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]].
==Manuals==
* [http://w140.com/tek_112.pdf Tektronix 112 Manual (PDF)]
* [http://w140.com/tek_112.pdf Tektronix 112 Manual (PDF)]


Internal photos needed.
==See Also==
* [[121]]


==Photos==
<gallery>
<gallery>
Image:Tek 112.jpg|1955 Catalog photo
tek_112_18.jpg
Image:Tek 112 front.jpg|Manual photo
Tek 112.jpg|1955 Catalog photo
Tek 112 front.jpg|Manual photo
Tek 112 main schematic.png|Main schematic
Tek_112.power_supply.png|Power Supply Schematic
Tek 112 calibrator schematic.png|Calibrator Schematic
tek_112_10.jpg|Bottom deck. Fan is missing; fan yoke still present.
tek_112_11.jpg
tek_112_13.jpg|Underside of bottom deck, front.
tek_112_14.jpg|Underside of bottom deck, rear.
tek_112_15.jpg|Underside of top deck.
tek_112_16.jpg|Vibration-isolated front-end amplifier
tek_112_20.jpg|Deflection sensitivity switch.
tek_112_3.jpg|Top internal
tek_112_4.jpg|Top front internal
tek_112_5.jpg|Top rear internal
tek_112_6.jpg
tek_112_7.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|Rear of front panel has sockets for holding spare tubes.
tek_112_2.jpg
tek_112_1.jpg
</gallery>
</gallery>
[[Category:Differential amplifiers]]
[[Category:Introduced in 1949]]

Revision as of 08:14, 8 August 2020

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 input impedance is 1 MΩ in parallel with 47 pF. The output impedance is 8000 Ω. 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.

Manuals

See Also

Photos