Tektronix 7S12
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Time Domain Reflectometer / Sampler
Tektronix 7S12 TDR/Sampler with S-6 and S-52 heads
Compatible with 7000-series scopes
Produced from 1971 to 1989
Manuals
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The Tektronix 7S12 is a Time Domain Reflectometer / Sampler plug-in for 7000-series scopes.
It occupies two mainframe plug-in bays (one vertical, one horizontal).
The 7S12 has two bays for S-series plug-in modules ("heads").
The right bay accepts a pulse generator or a trigger recognizer plug-in, whereas the left bay accepts a sampling plug-in.
The typical configuration is to have an S-6 on the left and an S-52 on the right for time domain reflectometry,
or a sampling head like the S-4 on the left and an S-53 on the right as a generic sampler.
The 7S12 can also control an optional 7S11 through its left side contacts, adding a second input channel.
Y axis can be scaled in voltage (mV) or distance (ρ) units, X axis in time or distance.
Specifications
Sweep modes
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Single / Repetitive / Manual / External input
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With S-6 and S-52
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- Pulse: 200 mV into 50 Ω
- Rise time: < 35 ps for incident step, < 45 ps for displayed reflection
- Jitter: < 10 ps
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With S-5 and S-54
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- Pulse: > 400 mV into 50 Ω
- Rise time: < 1.5 ns for displayed reflection of a shorted line
- Jitter: < 20 ps
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Sweep modes
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- free-running
- single
- manual
- external input
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Air Dielectric Range
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- 15 m (49 ft)
- 150 m (490 ft)
- 1500 m (4900 ft)
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Weight
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2.13 kg (4.7 lbs)
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Links
Pictures
Front view without sampling head plug-ins
Front view with S-6 sampling head and S-52 pulse generator
7S12 TDR "self portrait" in 7613 storage mainframe
7S12 as a sampler, displaying a 1 GHz sine using a S-6 sampling head and S-53 trigger recognizer, 2nd channel (top) on a 7S11 with S-4 sampling head.
Inside
Left side with cover. Side contacts to interface 7S11 are exposed.
Measurements
TDR
TDR "Self Portrait" — pulse reflected on S-6 "through" path (approx. 120 ps one way)
7S12 displaying the incident pulse from an S-52 (nom. < 25 ps) through an S-6 head (nom. < 30 ps). Displayed rise time ~35 ps confirms spec.
7S12/S-6/S-52 displaying pulse reflection from ~ 5 in semi-rigid SMA cable. Stored display of two traces. Left trace: cable only, right trace: cable plus SMA-to-BNC adapter (~ 25 mm)
7S12/S-6/S-52 displaying reflected pulse from end of 5 in semi-rigid SMA cable. Stored display overlaying multiple traces, left to right: cable alone, SMA-to-BNC adapter added, BNC f-f adapter added, (cheap) 50 Ω terminator added.
Full pulse pattern of a 7S12/S-52 in real time (top trace) and sampled (bottom trace) shown simultaneously on 7844. 7S12 trace at slowest possible sweep.
S-52 pulse in real time (top trace) and sampled (bottom trace) shown simultaneously on 7844. Approximately equal time scales.
Probe rise times
Rise time of a P6202 500 MHz FET probe measured on a 7S12 with S-52 and S-4 (in a 7844 mainframe), at 1 ns/Div
Rise time of a P6202 500 MHz FET probe measured on a 7S12 with S-52 and S-4 (in a 7844 mainframe), at 100 ps/Div
P6230 Rise time, no ground lead
P6230 Rise time, no ground lead, enlarged – 9.2 * 20 ps = 184 ps (equiv. to 1.9 GHz bandwidth)
P6230 with "low inductance" ground lead – rise time 400 ps, bandwidth 875 MHz
As a generic sampler
7S11 with S-4 and 7S12 with S-6 and S-53 displaying a 1 GHz sine in normal mode without storage. Sampling is evident.
7S11 with S-4 and 7S12 with S-6 and S-53 displaying a 1 GHz sine in high-res mode with variable-persistence storage on a 7613.