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2A60: Difference between revisions
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{{Plugin Sidebar | | {{Plugin Sidebar | ||
manufacturer=Tektronix |series=560-series scopes |type= 2A60 | | |manufacturer=Tektronix | ||
summary=1 MHz amplifier | | |series=560-series scopes | ||
image=Tek 2a60 front2.jpg | | |type=2A60 | ||
caption= 2A60 front view | | |summary=1 MHz amplifier | ||
introduced=1962 | | |image=Tek 2a60 front2.jpg | ||
discontinued=(?) | |caption= 2A60 front view | ||
|introduced=1962 | |||
manuals= | |discontinued=(?) | ||
* [ | |manuals= | ||
* [[Media:Tek type 60 irb.pdf|Tektronix Type 60/2A60 Instrument Reference Book (OCR | * [[Media:070-263.pdf|Tektronix 2A60 Manual] | ||
* [[Media:Tek type 60 irb.pdf|Tektronix Type 60/2A60 Instrument Reference Book]] (OCR) | |||
}} | }} | ||
The '''Tektronix 2A60''' is a 1 MHz, single-channel amplifier plug-in for [[560-series scopes]]. | The '''Tektronix 2A60''' is a 1 MHz, single-channel amplifier plug-in for [[560-series scopes]]. | ||
It was designated "Type 60" before being renamed 2A60 at serial number 820. | It was designated "Type 60" before being renamed 2A60 at serial number 820. | ||
The V/div positions of the 2A60 are somewhat unusual among Tektronix plug-ins. | The V/div positions of the 2A60 are somewhat unusual among Tektronix plug-ins. | ||
Most plug-ins use the | Most plug-ins use the 1−2−5 scale factors, e.g., 10 mV/div, 20 mV/div, 50 mV/div, 100 mV/div, etc. | ||
The 2A60's V/div positions are multiples of ten: 50 mV/div, 500 mV/div, 5 V/div, 50 V/div. | The 2A60's V/div positions are multiples of ten: 50 mV/div, 500 mV/div, 5 V/div, 50 V/div. | ||
This unusual feature was presumably a cost-cutting measure. | This unusual feature was presumably a cost-cutting measure. | ||
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(The [[59|Type 59]] was even cheaper, at half the price of the 2A60.) | (The [[59|Type 59]] was even cheaper, at half the price of the 2A60.) | ||
The 2A60 is similar to the [[3A75]], but the 3A75 has the standard | The 2A60 is similar to the [[3A75]], but the 3A75 has the standard 1−2−5 V/div positions and 4 MHz bandwidth. | ||
The linearization trick of diodes bypassing the cathode resistor (discussed | The linearization trick of diodes bypassing the cathode resistor (discussed below) is also used in the 3A75. | ||
In the [[Tek_Catalogs|1963 Tektronix catalog]], both models were listed. | In the [[Tek_Catalogs|1963 Tektronix catalog]], both models were listed. The 3A75 was 1.7× the cost of the 2A60. | ||
The 3A75 was 1.7× the cost of the 2A60. | |||
{{BeginSpecs}} | {{BeginSpecs}} | ||
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==Internals== | ==Internals== | ||
The input signal passes through a compensated attenuator and then into the input amplifier, a differential | The input signal passes through a compensated attenuator and then into the input amplifier, a differential amplifier formed from two [[6AU6]] pentodes. | ||
amplifier formed from two [[6AU6]] pentodes. The differential signal is then applied to a cathode-follower | The differential signal is then applied to a cathode-follower stage which drives the output stage. | ||
stage which drives the output stage. | |||
The output stage is a differential amplifier formed from both halves of a [[6DJ8]] dual-triode. | The output stage is a differential amplifier formed from both halves of a [[6DJ8]] dual-triode. | ||
To help linearize the output stage when it is making large positive or negative excursions, | To help linearize the output stage when it is making large positive or negative excursions, | ||
a pair of germanium diodes is placed in parallel with the resistor that connects the cathodes of output triodes. | a pair of germanium diodes is placed in parallel with the resistor that connects the cathodes of output triodes. | ||
The effect is that when the signal swings far in either direction, the gain degeneration (negative feedback) | The effect is that when the signal swings far in either direction, the gain degeneration (negative feedback) is reduced. | ||
is reduced. This helps keep gain stable across the range of signal voltages. | This helps keep gain stable across the range of signal voltages. | ||
==Pictures== | ==Pictures== | ||