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The Tektronix SD24 is a dual-channel TDR/Sampling Head. This sampling head has a rise time of 17.5 ps or less, with a typical 20 GHz equivalent-time bandwidth. The input impedance of the SD24 is 50 ohms, and the maximum safe input voltage is ±3 V. The SD24 can be inserted into an 11801, 11802, SM11, or they can be attached to Sampling Head Extender Cables. Each channel of the SD24 is also capable of generating a TDR pulse. The TDR pulse is a fast-rising step that is activated when the SD24 is in TDR mode. Each TDR pulse is applied to the input signal path for that channel. The acquisition portion of the sampling head is still functional for monitoring the incident pulse and this pulse's reflected components. The polarity of each channel's TDR pulse can be selected independently of the other channel. This allows for differential or common-mode testing of two coupled lines, besides independent testing of isolated lines.
Specifications.
Dot Transient Response: Adjustable to ±5% for signals from 0 to 0.5 V p-p; adjustable to unity for signals from 0.5 V to 1.0 V p-p.
Input Termination: 50 ±0.5 ohm.
Displayed Noise: With unity dot response typically 1.3 mV RMS; with smoothing: typically 0.6 mV RMS.
Max (Nondestructive) Input Voltage: ± 3.0 V.
Rise Time: <=17.5 ps.
Bandwidth: >= 20 GHz typical.
Time Coincidence Between Channels: <=10 ps.
Dynamic Range:1 V p-p within a ±1.6 V range.
Displayed Incident Rise Time: <= 28 ps, typical.
Displayed Reflected Rise Time: <= 35 ps.
TDR Pulse Amplitude: Adjustable to ±250 mV (polarity of either pulse may be inverted).
Time Coincidence Between TDR Pulses: Adjustable to less than 1.5 ps.
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