The present invention relates to a cooling device for an electron tube designated to amplify a high frequency signal. The invention is particularly suitable for cooling electron tubes that amplify radio frequency signals used for television or radio. The electron tube installed on a portal frame designed to hold the frame. The device includes a first hydraulic circuit inside which a first fluid circulates to cool at least part of the tube. The device also includes fluid exchanger to transfer heat transported by the first fluid to a second hydraulic circuit. The exchanger is also located on the portal frame.