A multitrack head for low frequency applications

The magnetic circuit of the head consists of two identical laminations each carrying alternate "C" and "L" shapes attached to a common selvedge. The read and write gaps are formed by the juxtaposition of the upper limbs of the "L" elements with the "C" elements, a shim of suitable thickness being inserted between them. The circuit is completed by welding the lower limbs of the "L"s to the "C"s, after a prewound coil has been slid over each "C" element. The pair of laminations are sandwiched between housings and the selvedge is ground off, separating the elements of each track. Heads have shown excellent read and write characteristics in the standard 9-track, 1/2 inch tape format at 1600 bits/inch, phase-encoded, at speeds up to 25 inches/s. At higher frequencies, the eddy-current losses in the magnetic circuit cause the performance to deteriorate.