First progress report on a multi-channel magnetic drum inner ...

6,1 Static Tester on Brush Tape BK 914
VI-3
Tests were made to determine the nermissible packing of pulses on
BrMsh Tape BK 914 under various recording and reading circumstances.
For this purpose dipoles were recorded on the tape with the disc
stationary by discharging a capacitor through the head. The recorded
dipole was then studied by rotating the disc and picking up the
signal with the same head. This signal was amplified, put on the
oscilloscope, and photographed. The peak-to-peak amplitude and the
span of the pulse were then determined by measuring the photograph.
If, was experimentally verified that the peak voltage induced in the
head is proportional to the speed of the magnetic material past the
head, and therefore amplitude measurements were all reduced to
microvolts at a standard peripheral speed of 1000 inches per second.
V'/hat is herein called the "extrapolated length" (see J'^rawing C-5-2021)
is taken as a criterion of permissible safe packing, so that the
reciprocal of this gives the allowable pulses per inch. That the
extrapolated length is a signifigant criterion of maximum packing
is shown by the experimental results of the next section. It should
be kept in mind, however, that this criterion does not necessarily
set a safe upper limit of maximum packing, but that in actual practice
some lower value will probably be used to give a safety factor of sufficient