Having stared at this mast so many times over the years, from the time when it was bristling with dishes, to the present day, I thought it was overdue a drone visit just to show how little remains of its original hardware.....it is 118m (387ft) tall and stands on a hill in Northamptonshire which is already about 217m (712ft) ASL Charwelton was selected around 1946 to provide a repeater station for the London to Birmingham televison link. This operated on 900 MHz and provided an alternative to a coaxial cable which was also available over the same route. The station is also listed on the 1956 "Backbone" map showing the TV route to Birmingham and other links to sites at "Coalville" and "Tring". These correspond to Copt Oak and Stokenchurch respectively in the network which was eventually devoped. As with the other 900 MHz sites the first provision was a guyed mast and later a small square tower but at Charwelton the 1960s development was a concrete tower of the "Chilterns" design. The original television link was routed via Turners Hill however with the new structures at Charwelton and Birmingham the intermediate site was no longer required. Photos from BT Archives show the tower strucurally complete by 1964 and apparently fully-equipped with horn antennas during 1966. A 1955 OS map shows "mast" and "Television Relay Station" and the 1980 plan at 1:2500 shows two small buildings, to the south of the tower, apparently in the same position as those on the 1955 map. These are still present on current aerial views and have possibly been retained for site sharing. (There is an unrelated steel tower in a separate compound to the south of the BT site.) Charwelton's location at the intersection of the London - Birmingham and Stokenchurch - Copt Oak links resulted in a "busy" site eventually having many large dishes facing in each direction. Although some "pruning" had occurred by 2009 a number of large dishes still remained in position as late as 2011, though apparently concentrated on the London/Birmingham route with none facing Stokenchurch but possibly some remaining towards Copt Oak. BT Archives has reports of an experimental 11 GHz link between Charwelton and Dunstable being in operation by 1974 and the use of "phase control height diversity" to overcome long-term fading which was experienced. The top of the structure appears to have been modified at some stage - the top section appears to have been removed giving a slightly "unfinished" look to the structure (a planning application in 1986 "Alteration to Existing Radio Tower" may be related). The site code YBFM may reflect an earlier name "Blackdown Farm" which appears on a 1948 diagram of the Control Circuit (a 4-wire telephone cable) for the original TV link.

• published: 25 Jul 2018
• views: 272