284

Tektronix 284
Pulse generator Front Panel Produced from 1967 to (?) Manuals Tektronix 284 Manual 070-0754-00 Tektronix 284 Manual 070-0754-00 (later version) Tektronix 284 Manual 070-0754-01 (no schematics) Tektronix 284 Factory Calibration Procedure, October 1967 Tektronix 284 Mod Kit 040-0487-02: Selectable Lead Time (All manuals in PDF format unless noted otherwise)

Manuals – Specifications – Links – Pictures

The Tektronix 284 is a pulse generator introduced in July 1967. It was designed by Fred Kawabata. 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. 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.

Links

284-based PPPG
Tek 284 page at amplifier.cd with detailed internals and repair/cal report
Tek 284 Repair at shaunmerrigan.info Photos of TD and output waveforms
284 rebuild including Airline and D-180 / Testing on Tek 577 by Zenwizard Studios @ YouTube

Documents Referencing 284

Document	Class	Title	Authors	Year	Links
Tekscope 1970 V2 N3 Jun 1970.pdf	Article	Tektronix Signal Sources		1970	2101 • 2901 • 114 • 115 • R116 • 106 • 191 • 284 • 140

Patents that may apply to 284

Page	Title	Inventors	Filing date	Grant date	Links
Patent US 3453403A	Power selection device	Eldon Hoffman	1966-08-18	1969-07-01	115 • 140 • 141 • 141A • 144 • 145 • 146 • 147 • 148 • 149 • 149A • 230 • 284 • 286 • 453 • 454 • 491 • 520A • 521A • 522 • 545B • 547 • 556 • 561B • 564B • 568 • 576 • 611 • 647A • 2101 • 2601 • 5030 • R5030 • 5031 • R5031 • 7503 • 7504 • 7704 • 7704A • 7904 • R7903
Patent US 3510690A	Transmission line coupled tunnel diode pulse generator	Fred Kawabata	1967-07-17	1970-05-05	284

Internals

The 284 generates a 1 GHz sinewave using a 2N3478 RF NPN transistor-based oscillator.

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 inside of a 50 Ω 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 20 μs):

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

The tripper pulse is produced by a snap-off 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 because they are really just stray capacitances. One side of each capacitor is the unconnected center pin of the bulkhead-mount female SMB connectors in the side of the airline. The other side of the 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.