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1A4: Difference between revisions
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series=500-series scopes | | series=500-series scopes | | ||
manuals= | manuals= | ||
* [ | * [[Media:070-0545-00.pdf|Tektronix 1A4 Manual]] (PDF) | ||
* [http://bama.edebris.com/manuals/tek/1a4 1A4 manual | * [http://bama.edebris.com/manuals/tek/1a4 1A4 manual @ BAMA] | ||
* [[Media:Tek 1a4 fcp jan 1967.pdf|Tektronix 1A4 Factory Calibration Procedure, January 1967]] | * [[Media:Tek 1a4 fcp jan 1967.pdf|Tektronix 1A4 Factory Calibration Procedure, January 1967]] | ||
* [[Media:Tek 1a2 cal outline.pdf|Tektronix 1A4 Calibration Outline (PDF, OCR)]] | * [[Media:Tek 1a2 cal outline.pdf|Tektronix 1A4 Calibration Outline (PDF, OCR)]] | ||
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It has four input channels and 50 MHz bandwidth. | It has four input channels and 50 MHz bandwidth. | ||
Type 1A4 was [[introduced in 1967]] and lasted until the end | Type 1A4 was [[introduced in 1967]] and lasted until the end of the [[500-series scopes]] line. | ||
of the [[500-series scopes]] line. | |||
The four channels are grouped into two groups of two channels. | The four channels are grouped into two groups of two channels. | ||
Type 1A4 has a special "trace slaving" mode which, | Type 1A4 has a special "trace slaving" mode which, when used in a [[547]] mainframe, allows channels 1 and 2 to be displayed using the A time base, | ||
when used in a [[547]] mainframe, | and channels 3 and 4 to be displayed with the B time base. This allows high-speed and low-speed signals to be displayed together, | ||
allows channels 1 and 2 to be displayed using the A time base, | |||
and channels 3 and 4 to be displayed with the B time base. | |||
This allows high-speed and low-speed signals to be displayed together, | |||
similar to what a dual-beam scope can do, but without some of the cost and complexity. | similar to what a dual-beam scope can do, but without some of the cost and complexity. | ||
Like the Type [[1A2]] and unlike the Type [[1A1]], | Like the Type [[1A2]] and unlike the Type [[1A1]], the Type 1A4 has a Trigger Output selector that controls | ||
the Type 1A4 has a Trigger Output selector that controls | |||
which channel provides triggering when the mainframe trigger is in Plug-In mode, | which channel provides triggering when the mainframe trigger is in Plug-In mode, | ||
for scopes having this feature ([[544]], [[546]], [[547]], [[549]], [[556]], late [[555]]). | for scopes having this feature ([[544]], [[546]], [[547]], [[549]], [[556]], late [[555]]). | ||
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==Internals== | ==Internals== | ||
The signal path of each channel | The signal path of each channel begins with the signal passing through the attenuators. | ||
Then it is clamped by two diodes and applied to the gate of a JFET source follower. | Then it is clamped by two diodes and applied to the gate of a JFET source follower. | ||
The source of the source follower is the trigger pickoff point. | The source of the source follower is the trigger pickoff point. | ||
From there the vertical signal path goes through an NPN emitter follower | From there the vertical signal path goes through an NPN emitter follower, then an NPN differential amplifier, at which point the signal becomes differential. | ||
Next, the signal passes through an analog multiplexer made with [[1N4152]] silicon switching diodes. | |||
at which point the signal becomes differential. | After the multiplexer network, the signal passes through a common base amplifier followed by [[6DJ8]] tube operating in common grid configuration. | ||
Next, the signal passes through an analog multiplexer | |||
made with [[1N4152]] silicon switching diodes. | |||
After the multiplexer network, the signal passes through a common base amplifier | |||
followed by [[6DJ8]] tube operating in common grid configuration. | |||
There is an "identify" switch for each channel, which when pressed shifts the trace up by ~3mm, to aid identification of the corresponding signal/channel. This is achieved by offsetting position control circuitry with a small resistance to shift position | There is an "identify" switch for each channel, which when pressed shifts the trace up by ~3mm, to aid identification of the corresponding signal/channel. | ||
This is achieved by offsetting position control circuitry with a small resistance to shift position. | |||
The 12.1V and -15V power for the plug-in is generated onboard using a step-up transformer, whose primary is connected to the 6.3 V heater supply from the mainframe and the two secondaries drive the onboard series regulators. | |||
==Pictures== | ==Pictures== | ||