PURPOSE: To enable the stable cooling of a high-power amplifier by providing a plurality of fans in the lower stage of an equipment rack mounted in the operation room and by circulating the cool air of an air-conditioner set in the operation room to the high-power amplifier to cool it so that waste heat is exhausted outside the vehicle.
CONSTITUTION: An operation room 5 and a high-power amplifier 6 are housed in the same space, and a plurality of fans 24 are mounted in the bottom of an equipment rack 4 to cool the high-power amplifier 6 so that cool air is blown in the direction of arrow 22. The equipment rack 4 is backed with a cover 23 to exhaust its heat, and heat of the high-power amplifier 6 is exhausted 20 from a plurality of exhaust ports 21. On the other hand, a dynamo 9 surrounded by a wall 17 sucks air through an intake 19 and exhausts air through an exhaust port 14, thereby making an air conditioner 3 circulate, cool, and exhaust heat. This enables the stable cooling of a high-power amplifier.