Tektronix 11A34 User Reference Supplement page 18

Overdrive Recovery
The waveform cbmge is due to skin effect loss in the longer cable. What is
total cable delay is only 5 ns. At 4W 11s the loss is still 0.02%.
This experiment shows tba
A second surprise is that skin effezt loss disappears almost completely (after
two cable delays) when one end is unterminated.
To observe this, use the short cable again, and selwt 1 hK? input impedance on
the llA34. Insert a 7X attenuator between the cable and the pulse generator to
improve the reverse termination and to provide the same amplitude signal as
before. Observe the -I-LX
division the skin effect loss is hard to detect without
The reason for this is that the skin effect loss is an increase in the efktive
series resistance of the cable.
voltage drop. see Qure 23.
Figure 23. Overdrive recovery using long (top) and short
unterminated Traces are offset two divisions and the photograph is a double
exposure.
2-6
importance of using a short cable to test overdrive
and
Without current, the cable develops no series