This is my version of Pirat. It works with 280 pps, and 140us time pulse, I add one transistor in the final stage to improve sound. The coils has 320uh , and the damping resistor is about 600 ohms. The coil has 3 turns of network cable with 8(295uh) or 9(325uh) inch. The 9 is best than 8.