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 |
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. Component News 259, 5 May 1978 says:
The most critical usage of mercury reed switches is in Tek's Type 109 Pulse Generator. (The 109 is used in-house for calibrating virtually all our product lines.) Unfortunately, there are no plans to replace this instrument line, which is dependent on the 260-0282-01 mercury reed switch for a 250 ps rise time pulse capability. To make matters worse, these switches are single-sourced from C. P. Clare, who must import them from Belgium. We are also having problems obtaining quality parts. (The raw switch costs approximately $5, but when the cost of rejects and added tooling are figured in , the cost per switch approaches $55.)
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
- 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
Pictures
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Front view
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Right internal
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Left internal
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Rear view (connector not original)
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flying spot caught with 7904, S6, 7T11, 7M11. 2.5 Vpk, Tr=240 ps
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schematic
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017-067 Charge network for 109
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017-067 Charge network for 109 (description)
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