Newly developed sendust video head for high coercive tape

The effective permeability (μeff) and the loss factor (\tan\delta/\mu_{eff}) of the sendust alloy in extremely thin condition were measured at the video frequency region. Results show that around the thickness of 15 μm, the effective permeability and the loss factor of the sendust alloy become comparable to those of Mn-Zn single crystal ferrite at high frequency region(>5MHz). A narrow track sendust video head was developed, for the first time, and its output properties were measured for both a high coercive tape(metal tape) and a conventional tape(CrO2tape). It was found that the output signal of the sendust head for the metal tape was 5 ∼ 6dB larger than for the CrO2tape at 0.5 ∼ 4MHz, and reached 6 ∼ 10dB larger at 5 ∼ 7MHz.