The Regional Scheme in England

Radio Record, Volume III, Issue 24, 27 December 1929, Page 4

The Regional Scheme in England

"Brookman’s Park Transmitter LATE in September the first of the B.B.G.’s new regional transmitting stations for the provision of alternative programmes commenced broadcasting. By the adoption of the regional scheme, the B.B.C. hopes to bring the whole of England within. crystal range of one of their stations. In fulfilment of this object the present broadcasting: nétwork of stations is gradually being replaced by a number of powerful transmitters strategically situated throughout the country. The first of these new stations to commence broadcasting is located at Brookman’s Park, a few miles north of London. The buildings which comprise this station are situated in a flat field of some 30 acres in area. At the four corners of the field are steel masts, which are of the lattice tower type and are insulated from earth at the base. The masts are only 200 feet. high -much lower than the height which would have been chosen from an engineering point of view. Unfortunately, there are Air Ministry limitations on the height of masts which may be erected near London. Other regional stations throughout the country, however, will have masts which will probably be about 700 feet high. The distance between each of the masts at. Brookman’s Park is 600 feet, and there are 900 feet between the building and each aerial. There is an electrically lit red lantern at the top of each mast which serves to warn aircraft attempting to land in the neighbourhood. Below the centre of each aerial is a small, square, stone building, containing the feeder system, coupling the feeder wires- from the main building to: the aerial itself, and underneath, radiating from this building is the earth system consisting of a number of wires buried one foot below the surface of the ground, the ends of the wires forming an oval extending about 200 feet on each side of its par- =

ticular aerial, and 150 feet beyond each mast, . The power-house itself contains four 300 horse-power Diesel enginés, to each of which is coupled a direct-current dynamo generating 220 volts. These engines, which are each of six cylinders, are mounted on a single bed of concrete which is s0 constructed that vibration cannot be transmitted to other parts of the building. The supply is direct currént at 220 volts in. order to make possible the use of a "puffer" battery. The storage battery has a capacity of 2000 ampere hours, and is intended to supply current when the transmitters are not running. The main motor generator room contains six large motor generators besides smaller ones, While the station is running on full load two motor generators will be in use-one for each transmitter, while the third will act as a spare for either transmitter. The other three large machines in this room are for heating the filaments of the transmitting valves. It is interesting to note that while, the average wireless set absorbs about .6 ampere to light the valves, the transmitting valves at this new station absorb 2600 amperes! The transmitters normally deliver 30kw. to each aerial and employ modulation at low power. There is first a drive stage, for which special precautions are taken to keep the frequency constant to within about 200 cycles. The output from the drive valve is applied to the separator stage, after which comes the modulated amplifier. This is the stage at which the moidulation takes place, and the power level is approximately ikw. Next to the main transmitter Hall are two control, rooms where the programmes are received on the land-lines running to the studio at Savoy Hill. These two rooms, one for each transmitter, contain all the necessary amplifiers and controlling gear, while the lines to Savoy Hill are underground all the way to ensure constancy of. performance and reliability. In these control rooms are also small receiving sets built-in so that the modulation can be tested as received from the aerial of each transmitter, as well as controlled and watched in the ordinary line circuits. Everything has been done to make the station as up to date and as. per-t

= fect as possible, and there is no doubt that it is a wonderful achievement from a technical point of view, and also from the point of view of appearance, for the station is systematically and artistically laid out. The cost of this modern wonder is stated to be under £150,000, and its. opening marks the beginning of a most important era in he history of British broadcasting. .