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.
|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|
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.
Be aware during servicing that the thermal breaker is on full mains and has no protection cover!
- Jim Williams, Linear Technology Application Note 120, "1 ppm Settling Time Measurement for a Monolithic 18-Bit DAC" - see Appendix H (p.30)
- Report comparing RG-58 with RG-174 using Tek 109 and Tek 661 (PDF)
- Tek 109 page @ amplifier.cd
017-067 Charge network for 109