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1A4 (view source)

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{{Plugin Sidebar | designers=|
{{Plugin Sidebar
manufacturer=Tektronix | type=1A4 |
|manufacturer=Tektronix
summary=50 MHz quad input amplifier plugin |
|series=500-series scopes
image=Tek 1a4 frontx.jpg |
|type=1A4
caption=Tektronix 1A4 front |
|summary=50 MHz quad input amplifier plugin
years=1967 - 1975 |
|image=Tek_1A4_Front_–_Tight.jpg
introduced=1967 |
|caption=Tektronix 1A4 front
discontinued=1974 |
|introduced=1967
series=500-series scopes |
|discontinued=1974
manuals=
|designers=Al Allworth
* [http://w140.com/mmm/tek-1a4.pdf Tektronix 1A4 Manual (PDF)]
|manuals=
* [http://bama.edebris.com/manuals/tek/1a4 1A4 manual on BAMA (offline?)]
* [[Media:070-0545-00.pdf|Tektronix 1A4 Manual]] (PDF) / [https://w140.com/mmm/tek-1a4.pdf Alternate]
* [[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 1a4 mods.pdf|Tektronix 1A4 Product Modification Index]]
}}
}}
The '''Tektronix Type 1A4''' is a 1-series vertical plug-in for [[500-series scopes]].
The '''Tektronix Type 1A4''' is a 1-series vertical plug-in for [[500-series scopes]].
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 which channel provides triggering when the mainframe trigger is in Plug-In mode,
the Type 1A4 has a Trigger Output selector that controls  
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 of the 1A4 is as follows. 
The signal path of each channel begins with the signal passing through the attenuators.   
First the signal passes 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.   
followed by an NPN differential amplifier,  
Next, the signal passes through an analog multiplexer made with [[1N4152]] silicon switching diodes.   
at which point the signal becomes differential.   
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.
After the multiplexer network, the signal passes through a common base amplifier followed by [[6DJ8]] tube operating in common grid configuration.


The 12.1V and -15V power for the plug-in is generated onboard using a step-up transformer, whose primary is connected to the 6.3V heater supply from the mainframe and the two secondaries drive the onboard series regulators.
There is an "identify" switch for each channel, which when pressed shifts the trace up by ~3 mm, to aid identification of the corresponding signal/channel.  
This is achieved by offsetting position control circuitry with a small resistance to shift position.


The 12.1 V and −15 V 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==
Retrieved from "https://w140.com/tekwiki/wiki/Special:MobileDiff/62618...81787"

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