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The Tektronix Type 512 is a | {{Oscilloscope Sidebar | | ||
title=Tektronix 512| | |||
summary=2 MHz scope | | |||
image=Tek 512 front.jpg | | |||
caption=Tek 512 | | |||
introduced=1948 | | |||
discontinued=(?) | | |||
manuals= | |||
* [http://w140.com/tek_512_early.pdf Tektronix 512 Manual (early, PDF)] | |||
* [http://w140.com/tek_512.pdf Tektronix 512 Manual (late, PDF)] | |||
}} | |||
The '''Tektronix Type 512''' is a 2 MHz oscilloscope [[introduced in 1948]]. | |||
Tektronix engineer Logan Belleville did most of the | Tektronix engineer Logan Belleville did most of the | ||
design work for the 512. The maximum sensitivity is | design work for the 512. The maximum sensitivity is 5 mV/cm. The vertical signal path, fully differential and DC coupled from the front panel A and B inputs to the vertical deflection plates, is as follows: | ||
fully differential and DC coupled from the front panel A and B inputs to the vertical deflection plates, | |||
is as follows: | |||
* Stage 1: differential, [[5879]] pentodes | * Stage 1: differential, [[5879]] pentodes | ||
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Built-in true differential inputs are also seen in later scopes such as the [[502]], [[503]], and [[504]]. | Built-in true differential inputs are also seen in later scopes such as the [[502]], [[503]], and [[504]]. | ||
The input impedance is | The input impedance is 1 MΩ in parallel with 45 pF. The 512 uses a total of 3 kV of acceleration voltage: -1500 V for the cathode, +1500 V for the anode. It weighs 54 pounds and uses 280 watts. It has no [[thermal cutoff]]. | ||
voltage: - | |||
Up to serial number 2525, the 512 used the [[5CPA]] CRT. After that, the [[5ABP]] CRT was used. | Up to serial number 2525, the 512 used the [[5CPA]] CRT. After that, the [[5ABP]] CRT was used. | ||
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Tektronix 512 oscilloscopes with serial numbers 101 through 2146 | Tektronix 512 oscilloscopes with serial numbers 101 through 2146 | ||
have an unregulated HV power supply that uses a | have an unregulated HV power supply that uses a 2 kHz oscillation frequency and | ||
has no regulation. Starting at serial number 2147, the HV power | has no regulation. Starting at serial number 2147, the HV power | ||
supply runs at | supply runs at 70 kHz and has regulation in form that is typical | ||
of Tek scopes of the 1950's and 1960's. | of Tek scopes of the 1950's and 1960's. | ||
The CRT cathode voltage is compared with the - | The CRT cathode voltage is compared with the -150 V supply and | ||
an error signal is produced, which controls the screen voltage on | an error signal is produced, which controls the screen voltage on | ||
the HV oscillator pentode. | the HV oscillator pentode. | ||
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the blanking signal from the sweep circuit to control the DC voltage | the blanking signal from the sweep circuit to control the DC voltage | ||
of the "grounded" end of the secondary that produces the CRT grid voltage. | of the "grounded" end of the secondary that produces the CRT grid voltage. | ||
When the grounded end is shifted up and down by | When the grounded end is shifted up and down by 50 V, the CRT grid voltage | ||
is shifted up and down by | is shifted up and down by 50 V relative to the constant cathode voltage, | ||
thereby controlling CRT beam current. | thereby controlling CRT beam current. | ||
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taken in the 512 was to modulate the blanking signal on a carrier, | taken in the 512 was to modulate the blanking signal on a carrier, | ||
much like a CW transmitter sending morse code (or any other on-off signal). | much like a CW transmitter sending morse code (or any other on-off signal). | ||
The signal passes through a transformer which has approximately | The signal passes through a transformer which has approximately 0 V<sub>DC</sub> | ||
on the primary side and approximately -1500VDC on the secondary side. | on the primary side and approximately -1500VDC on the secondary side. | ||
The signal from the secondary is demodulated, recovering the blanking signal, | The signal from the secondary is demodulated, recovering the blanking signal, | ||
which controls the grid voltage on the CRT. | which controls the grid voltage on the CRT. | ||
==Pictures== | |||
<gallery> | <gallery> | ||
Image:Tek 512 front.jpg | Image:Tek 512 front.jpg | ||
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Image:Tek 512 bottom rear.jpg|Bottom rear | Image:Tek 512 bottom rear.jpg|Bottom rear | ||
</gallery> | </gallery> | ||
[[Category:Tube scopes]] | |||