109

The Tektronix Type 109 is a pulse generator introduced in 1962. It uses a GR-874 50 Ω output connector and has a specified rise time of 250 ps.

Key Specifications

Rise time	250 ps
Pulse frequency	550 to 720 Hz
Pulse length	0.5 ns to 100 ns with a single charge line between the two charge line connectors, or up to 300 ns at half pulse rate with one open-ended charge line (other connector grounded)
Pulse amplitude	Internal supply: 0 to 50 V variable in three ranges (0.5 V, 5 V, 50 V), positive or negative, or external up to ± 300 V

Manuals

Tektronix 109 Manual (PDF)

Internals

The 109's operating principle is that of a charged transmission line pulse generator with a mechanical reed switch and external 50 Ω transmission line/lines attached through two GR-874 50 Ω connectors. The length of the external cables determines the impulse width. Using two transmission lines of non-equal length, alternating pulses having different width can be produced. Alternatively, an R-C network can be used to create pulses with R-C decay characteristic but longer duration.

The pulse-generating switch in the 109 is a mechanical mercury switch, which limits pulse frequency to about 600 Hz. Moreover, this switch has a relatively short life time (200 hours) — if the operator forgets to shut the 109 down over the weekend and some holidays, the reed switch will need replacement.

The internal voltage source is adjustable from 0 to 50 V in three ranges (0.5 V, 5 V, 50 V), either positive or negative. Using external voltage sources, pulses up to 300 V of either polarity are possible, including alternating positive/negative pulses.

Repair issues

Be aware during servicing that the thermal breaker is on full mains and has no protection cover!

Links

Pictures

Front view
Right internal
Left internal
Rear view (connector not original)
flying spot caught with 7904, S6, 7T11, 7M11. 2.5 V_pk, T_r=240 ps
schematic
017-067 Charge network for 109
017-067 Charge network for 109 (description)
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109