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284: Difference between revisions
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The Tektronix 284 is a pulse generator. | The '''Tektronix 284''' is a pulse generator. | ||
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 pulse comes out one output connector. | ||
The sine wave and square wave come out another output connector. | The sine wave and square wave come out another output connector. | ||
Both outputs are 50 | Both outputs are 50 Ω [[Connectors#GR-874|GR-874]]. | ||
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 is mounted | D180, Tektronix part number [[152-0329-00]]. D180 is mounted | ||
inside of a 50 | inside of a 50 Ω airline (rigid coaxial transmission line with | ||
only air between the center conductor and the shell). | 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 | ||
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File:Tek 284 td.JPG|Tunnel diode in housing | File:Tek 284 td.JPG|Tunnel diode in housing | ||
</gallery> | </gallery> | ||
[[Category:Pulse generators]] | |||