846 
cable circuit was too small for direct application to the oscillograph 
and therefore was applied to the amplifier portion of a Hewlett Packard 
Model 400 C Voltmeter which served as a pre-amplifier for the DuMont Type 
248 Cathode-Ray Oscillograph. 
Plate 11(a) shows the wave form of the single-ended output of 
the square-wave generator when applied directly to the oscillograph. One 
period of the 10 ke wave is shown and hence the time base for the complete 
wave form shown is 100 microseconds. 
Plate 11(b) shows the test wave form after it had passed through 
the pre-amplifier used with the oscillograph. This was obtained by passing 
the output of the square-wave generator through the pre-amplifier only 
before reaching the oscillograph. However the cable with its termination 
was also connected to the output terminals of the square-wave generator to 
serve as the normal load on the square-wave generator during this test. 
Plate 11(c) for k = 0, m = 2, shows the extreme overshoot of 
the initial response and the'violent oscillations that continue throughout 
the 50 microsecond time interval after the initial response for the case 
where the terminating resistance is zero. Similar oscillations throughout 
the 50 microsecond time interval were obtained for values of m= 1, 4, and 
6, with k s O in each case. 
Plate 11(d) for k = 1, ms 2, shows an initial overshoot of 
approximately 30 percent. The corresponding calculated curve of Plate 8 
predicts an initial overshoot of 50 percent. The curve of Plate 8 also 
indicates the oscillations to be expected out to time t w= 5RC, but yields 
no information after this time value because only two terms were retained 
in the series expansion for the relative amplitude. Plate 11(d) shows 
oscillations in close agreement with the calculated curve out to time 
t = 5RC, and also indicates that the oscillations are completely damped 
out after time t = 5RC. For Plate 11 the test length of 955 feet of 
special Simplex twin coaxial cable has a transit time RC of 1.47 microseconds. 
Since the initial response occurs at time t = RC, the oscillations predicted 
by Plate 8 and obtained by measurement in Plate 11(d) exist over a time 
interval from t = RC to t s 5RC or for 5.88 microseconds. This time interval 
can readily be identified in Plate 11(d) when it is remembered that the time 
base shown after the initial response is 50 microseconds. 
Plate 1l(e) for k = 1.5, m =» 2, shows a greatly reduced initial 
overshoot which is not greater than 10 percent. This is to be compared with 
a 20 percent overshoot predicted by Plate 8. The oscillations are again 
evident for a time interval corresponding to the calculated interval of 
5.88 microseconds, after which they are completely damped. 
Plate 11(f) for k = 2, m=#.2, shows the complete elimination of 
the initial overshoot. Indeed an "undershoot" on the order of 10 percent 
_ can be seen. This compares with zero overshoot predicted by Plate 8. The 
oscillations again exist only during the 5.88 microsecond time interval out 
to t » 5RC. 
= § = NOLM 10467 
