| Height of concrete shell:   | 
                   274.32 m (900 ft) | 
                  
                     NEW 
  
IBA / NTL 
                            data sheets 
  | 
                
                
                  | Height of microwave link room:  | 
                   274.32 m (900 ft) | 
                
                
                  | Length of aerial structure at top of mast:  | 
                   55.7 m (184 ft) | 
                
                
                  | Diameter of shell at base:  | 
                   24.4 m (80 ft) | 
                
                
                  | Diameter of shell at top:  | 
                   6.5 m (21ft 3 in) | 
                
                
                  | Wall thickness at base:  | 
                  533 mm (21 in) | 
                
                
                  | Wall thickness at top :  | 
                  350mm (13.5in) | 
                
                
                  | Amount of concrete used:  | 
                   7 000 m3 (1 900
                    yd3) | 
                
                
                  | Overall
                    weight:  | 
                   11200 tonnes | 
                
                
                  | Weight of foundations:  | 
                   5 400 tonnes | 
                
                
                  | Overall depth of foundations: | 
                   6.1 m (20 ft) | 
                
                
                  | Weight of transmitting aerial structure: | 
                   63 tonnes | 
                
                
                  | Loss
                    in co-axial feeder:  | 
                   1.5 dB | 
                
                
                  | Collapse of previous mast:  | 
                   19-Mar-1969 | 
                
                
                  | Initial briefing for new structure:  | 
                   16-May-1969 | 
                
                
                  | Start of design work:   | 
                   June 1969 | 
                
                
                  | Contractor on site :  | 
                   August 1969 | 
                
                
                  | Concrete structure completed:  | 
                   September 1970 | 
                
                
                  | Aerial mast in position: | 
                   November 1970 | 
                
                
                  | Start of UHF service:  | 
                   21-Jan-1971 | 
                
                
                  | Start of VHF service  | 
                   21-Apr-1971 |