Abstract: High-power transmitter valves are located in a housing through which a fan feeds a cooling air stream between an inlet point and an outlet point, the inlet air temperature being required to lie within a range set by the valve manufacturer. The device according to the invention, which is located outdoors, comprises a first duct connected to the inlet point of said housing and a second duct connected to the outlet point thereof. Both the first and second ducts are connected to the outside atmosphere, the first by way of a filter and the second by way of a throttle valve which enables a fraction of the air flowing through the second duct to be recycled to the first duct upstream of the filter, and which for this purpose is controlled by a temperature transducer located in the first duct downstream of filter.