The RAAF High Frequency Direction Finding (HF/DF or “Huff Duff”) Station was built as an aviation navigational aid during 1942, and was later used by the Australian Special Wireless Group (ASWG) for intelligence gathering purposes. It is located between Tolga and Kairi, on the north side of Shead Road, northwest of the junction with Yadgin Road.

The site comprises two reinforced concrete buildings. One is a concrete room, 6.3 metres by 3.35 metres and about 2.8 metres high, which housed a power generating plant. This building contains a doorway and one window, and is now incorporated under a large open workshop.

A second concrete building is located in open farm land about 200 metres to the north-west. This round building, called the Set Room, housed the HF/DF receiver console, and is constructed of concrete with a flat roof. The interior was formerly lined with a ‘caneite’ type board which was fixed to timber battens on the walls and roof. The Set Room, 4.4 metres in diameter, 3 metres high, with walls and roof 400mm thick, has one doorway (with a recent steel door) and four high ventilation openings screened by steel louvres. The four vertical antennae and copper mat earthing system have been removed.