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The Tektronix 284 is a pulse generator. | {{Instrument Sidebar | ||
|manufacturer=Tektronix | |||
|model=284 | |||
|class=Pulse generator | |||
|series= | |||
|summary=Pulse generator | |||
|image=Tek_Type_284_Front.jpg | |||
|caption=Front Panel | |||
|introduced=1967 | |||
|discontinued=(?) | |||
|designers= | |||
|manuals= | |||
* [[Media:070-0754-00.pdf|Tektronix 284 Manual 070-0754-00]] | |||
* [[Media:070-0754-01.pdf|Tektronix 284 Manual 070-0754-01]] | |||
* [[Media:Tek 284 fcp oct 1967.pdf|Tektronix 284 Factory Calibration Procedure, October 1967]] | |||
* [[Media:040-0487-02.pdf|Tektronix 284 Mod Kit 040-0487-02: Selectable Lead Time]] | |||
}} | |||
The '''Tektronix 284''' is a pulse generator [[introduced in 1967|introduced in July 1967]]. | |||
Its output modes include: | Its output modes include: | ||
* | * 70 ps risetime pulse, 200 mV, 50 kHz repetition rate, 1 μs pulse duration (5% duty cycle) | ||
* | * Sine wave, 1 GHz or 100 MHz, 100 mV | ||
* Square wave, 10 MHz, 1 MHz or 100 kHz, 10 mV, 100 mV, or 1 V | |||
* | |||
Only one mode can be used at a time. | Only one mode can be used at a time. The pulse comes out one output connector. The sine wave and square wave come out another output connector. Both outputs are 50 Ω [[GR-874]]. | ||
The pulse comes out one output connector. | |||
The sine wave and square wave come out another output connector. | |||
Both outputs are | |||
The 284 generates a | The 284 generates a 1 GHz sinewave using a [[2N3478]] RF NPN transistor-based oscillator. | ||
[[2N3478]] RF NPN transistor-based oscillator. | |||
The 284 generates the | The 284 generates the 70 ps risetime pulse using a 20 mA, 1.5 pF tunnel diode, D180, Tektronix part number [[152-0329-00]]. | ||
D180, Tektronix part number 152-0329-00. D180 is mounted | D180 is mounted inside of a 50 Ω airline (rigid coaxial transmission line with only air between the center conductor and the shell). | ||
inside of a | |||
only air between the center conductor and the shell). | |||
D180 is in series with the airline's center conductor. | D180 is in series with the airline's center conductor. | ||
One end of the airline contains three resistors for biasing the tunnel diode and terminating the transmission line. | One end of the airline contains three resistors for biasing the tunnel diode and terminating the transmission line. | ||
The other end of the airline is the GR-874 pulse output connector. | The other end of the airline is the GR-874 pulse output connector. | ||
For each pulse (every | For each pulse (every 20 μs): | ||
* the biasing current is switched on, putting D180 close to its peak current | * the biasing current is switched on, putting D180 close to its peak current | ||
* a capacitively coupled "tripper" applies a short current pulse to D180, causing it to switch to its high-voltage state | * a capacitively coupled "tripper" applies a short current pulse to D180, causing it to switch to its high-voltage state | ||
* the biasing current is switched off, causing the tunnel diode to fall back to the low-voltage state | * the biasing current is switched off, causing the tunnel diode to fall back to the low-voltage state | ||
The tripper pulse is produced by a snap diode. | The tripper pulse is produced by a [[snap-off diode]]. | ||
Air gap capacitors couple the tripper pulse to the tunnel diode. | Air gap capacitors couple the tripper pulse to the tunnel diode. | ||
These capacitors, C185 and C186, are drawn with dashed lines in the schematic | These capacitors, C185 and C186, are drawn with dashed lines in the schematic because they are really just stray capacitances. | ||
because they are really just stray capacitances. | One side of each capacitor is the unconnected center pin of the bulkhead-mount female [[SMB connector]]s in the side of the airline. | ||
One side of each capacitor is the unconnected center pin of the bulkhead-mount female | The other side of the capacitor is the conductive tunnel diode mount in the core of the airline. | ||
[[ | |||
capacitor is the conductive tunnel diode mount in the core of the airline. | |||
Modification kit [[040-0487-00]] changes the times selectable with the lead time switch. | |||
==Links== | |||
* [https://www.youtube.com/watch?v=8kweJOFoi1g Zenwizard Studios - Unit I rebuild including Airline and D-180] | |||
* [https://www.youtube.com/watch?v=xvBzUflcYmE Zenwizard Studios - Unit I rebuild including Airline and D-180 testing on Tek 577] | |||
==See Also== | |||
* [[284-based PPPG]] | |||
* [http://www.amplifier.cd/Test_Equipment/Tektronix/Tektronix_other/284.html Tek 284 page at amplifier.cd] with detailed internals and repair/cal report | |||
==Photos== | |||
<gallery> | <gallery> | ||
Tek_Type_284_3-4.jpg|3/4 View | |||
Tek_Type_284_Rear.jpg|Rear Panel | |||
Tek_Type_284_Interior_Top.jpg|Interior Top | |||
Tek_Type_284_Interior_Bottom.jpg|Interior Bottom | |||
Tek_Type_284_Interior_Left.jpg|Interior Left | |||
Tek_Type_284_Interior_Right.jpg|Interior Right | |||
Tek 284 td.JPG|Tunnel diode in housing | |||
284-oscillator.jpg | Oscillator | |||
Tek 284 diode pulser.png|Fast pulse output schematic | |||
Tek 284 pulser drawing.jpg|Pulser module drawing | |||
Tek 284 front.jpg | |||
Tek 284 front2.jpg | |||
Tek 284 side.jpg | |||
Tek 284 rear.jpg | |||
Tek 284 clean front.jpg | |||
Tek 284 clean rear.jpg | |||
Tek 284 and 067-0508-00.jpg | 284 with [[067-0508-00]] | |||
</gallery> | </gallery> | ||
[[Category:Pulse generators]] |
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