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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: | ||
* 70ps risetime pulse, 200mV | * 70ps risetime pulse, 200mV, 50kHz repetition rate | ||
* 1GHz sine wave, 100mV | * 1GHz sine wave, 100mV | ||
* 100MHz sine wave, 100mV | * 100MHz sine wave, 100mV | ||
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[[2N3478]] RF NPN transistor-based oscillator. | [[2N3478]] RF NPN transistor-based oscillator. | ||
The 284 generates the | The 284 generates the 70ns risetime pulse using a 21mA tunnel diode, | ||
D180, Tektronix part number 152-0329-00. D180 is mounted | |||
inside of a 50-ohm airline (rigid coaxial transmission line with | |||
only air between the center conductor and the shell). | |||
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. | |||
The other end of the airline is the GR-874 pulse output connector. | |||
For each pulse (every 20us): | |||
* 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 | |||
* the biasing current is switched off, causing the tunnel diode to fall back to the low-voltage state | |||