PG508

Manuals – Specifications – Links – Pictures

The Tektronix PG508 is a 50 MHz pulse generator plug-in for the TM500 system.

Pulses can be triggered by an external input, a manual trigger button, or an internal period generator (optionally gated by the trigger input). The trigger signal can be undelayed, delayed by a selectable time, or both (in which case double pulses are generated). The pulse duration, leading and trailing edge transition times, high- and low-level amplitude can be controlled independently.

Period, delay, duration, and transition time switches each feature a custom position where a user-supplied internal capacitor determines the timing.

Key Specifications

Period	external, or internal <20 ns to >200 ms in 7 decade steps plus variable; ≥200 ms possible in custom range
Jitter	<0.1% +50 ps
Delay Time	<10 ns to >100 ms in 7 decade steps plus custom position and variable control; ≥100 ms possible in custom range
Pulse Duration	square, or <10 ns to >100 ms in 7 decade steps plus custom position and variable control; ≥100 ms possible in custom range
Transition time	Ranges 5 ns to 500 μs in decade steps plus custom position; separate  ×1 to ×100 variable controls for leading and trailing edge (5 ns to 50 ms effective)
Output level	High and low levels adjustable independently in −20 V to +20 V range, limited to max. 20 Vp-p / min. 1 Vp-p (open circuit), 50 Ω source impedance (−10 V to +10 V, 0.5 to 10 Vp-p into 50 Ω)
Trigger/Gate input	Sensitivity 80 mVp-p to ≥10 MHz, 250 mVp-p to ≥50 MHz at 50 Ω impedance, max. ±5 Vpeak; 1 MΩ // 20 pF optionally selectable (internal switch), max. ±20 Vpeak

Rear Interface

(right-hand plug-in slot as viewed from front)

• 27B/28B(GND) Trig output (complement polarity installed; for normal polarity, front panel input requires optional cable and front output disconnection) [note error on manual p.1-12; table 1-13 is correct]
• 24B/25B(GND) Trig input (with optional cable, front panel input must be disconnected)
• 25A/26A(GND) Amplitude Monitor (from output via 27 kΩ)
• 22A External Low Level Control Input (requires internal jumper and trim)
• 22B External High Level Control Input (requires internal jumper and trim)

Custom connection solder pads are available on the left plug-in slot, which is otherwise used only for the associated pass transistors in the mainframe.

References

• Designs by the Masters – ±20 V, 5 ns, 50 Ω Amplifier (detailed discussion of the PG508 output stage). Horowitz & Hill, Art of Electronics - The x-Chapters, p.150+

Links

• Zenwizard Studios - PG508 Repair and Calibration

Pictures

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  Output board (The black coax connection from the output stage to the left plug-in slot is non-standard.)

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Custom ICs used in the PG508