The Erection and Installation of 2YA

Radio Record, Volume I, Issue 1, 22 July 1927, Page 6

The Erection and Installation of 2YA

Comprehensive Survey of Equipment by : Station Engineer

(By MR.

J. M.

BINGHAM

Assoc;

M.1.R.E.)

‘The new broadcast station 2YA, just completed, marks another milestone in the progress of the Radio Broadcasting Company, Ltd. It is only a matter of eight months or so since the company decided to erect a high-power station in the neighbourhood of Wellington, and immediately following this decision the first matter to be given consideration was a selection of a suitable site for the transmitter. With this end in view a certain. amount of exploration work was done before the present site ‘on Mount Victoria was finally decided upon. There has been some criticism levelled against the company for having erected the new station in close proximity to Wellington city, but the selection of the present site was made ‘only after due consideration had been ‘given to the requirements of the type of station to be installed. , Factors in Situation. First and foremost was the question of "getaway." It was obvious that in a hilly location such as Wellington, it was not possible to place the station in a valley, owing to the screening effects of the surrounding hills ‘The station, therefore, had to be high up. Then there was the question of landline communication. The studio from which the artists were to broadcast would be situated mear the heart of the city, and in order to have the landlines connecting the studio with the station as free as possible from interference and other defects, the distance had to be as short as possible. Then again it was inadvisable to use up val~

avs wessulity sited aah ver cusy aCcess had to be obtained from the city Directional effects, water supply for the valves, and other details had to be looked into, and in all these respects the Mount Victoria site came nearest to the ideal. Negotiations for purchase of the land required were immediately put in hand, levels were taken, and plans for the building were prepared. Excavations were made and the foundations for the

building were laid out approximately in the middle of the strip of land on the ridge of the hill, Anchor blocks were. set in for the towers, wkich had previously been ordered, and which were to be similar to one of the towers at 8YA. Work proceeded apace, bu when the building was partly completed it was found necessary to make alteratious to the original design owing to the fact that certain details of the -izes of the equipment to be supplieu were found to be imcorrect. Meantime the equipment arrived, and in order to facilitate assembly a galvanised iron shed was erected wud the equipment stored therein. About this same time the tower material arrived, and as the anchor blocks were already in position, the work of erecting the towers was also put in hand. This work

had to be done piecemeal, as it was impossible to do any tower erection on windy days and windy days were more often the rule than the exception. Towers Very Satisfactory. A word here about the towers may not .be amiss. The towers supplied were manufactured by the Canadian Bridge Company, of Toronto, Canada,. and were specially designed to with-

stand the hurricane conditions likely to be encountered in the exposed location of. Mount Victoria. All tower materia is of steel, hot galvanised and arrived in bundles drilled and marked ready for erection. The accuracy with which the tower manufacturers did their work can be gauged from the fact that both the towers fitted together like a meccano set without the necessity for drilling or drifting. The towers as completed stand 154 feet high from base to cap, and have a spread at the base of 28 feet. Each of the anchor blocks for the legs of the towers is designed for over 25 tons uplift, and as the towers themselyes are designed to withstand a wind pressure: of 120 miles per hour, together with an aerial pull of ae L500Ib., a value considerably in excess of anything likely to be encountered in

Wellington, the safety of the structures is practically assured. While the towers and building were in the course of erection, the engineers were busy with the assembly of the various units of the radio equipment, and as soon as the building was ready the assembly work had reached a stage where the various units could be movel in and erected in position. A skidway was constructed between the assembly shed and the main building, and one fine day all the equipment was moved ‘n, The actual installation then commenced, and the whole of the work from the initial assembly to the final tuning up was done by the. writer with one assistant. Adjusting the Plant. When the power was first switched on, it was found that there were certain minor defects in various portions of the apparatus. These points were scon rectified, however, and the plant worked in a highly satisfactory manner, The transmitter equipment is located im a room approximately 25 feet hy 30 feet, while a separate room 25 feet by 12 feet houses the various water pumping machinery, and motor generators for grid bias, high tension and filament lighting. ‘The valyes used in the transmitter are water cooled, and itt connection with the water system is a series of radiators and expansion tank which are placed in a louvred house on the roof of the main building. AN inter-unit wiring is in galvanised run conduit in ducts beneath the floor level. These ducts also contain the water supply pipes to the valves, Lhe aerial system consists of a 4-wire flat top ‘I’ aerial with 200 feet top measurement and cage down lead. ‘The wires in the top are spaced approxiwately seven feet and cach terminates in a string of four 50,000 volt strain insulators, The lead-in comes throngh the roof almost immediately above the transmitter through a 110,000 volt leadin bushing. No counterpoise is as yet erected, and although full provision was made for this arrangement in the original layout of the station, it is doubtful if its erection would increase the efficiency of the station in any way. The ground system, which consists of a fan-like arrangement of buried earth wires, has proved highly satisfactory, and on measurement it was found that the whole aerial-earth system had a radiation resistance of approximately 24 ohms at 420 metres, The Studio and Layout, | The studio from which the pro-

gramimes are to be broadcast is sitnated in the city, a distance of approximately two miles from the transmitting station. The furnishings of the studio are described elsewhere, but apatt from this there are many technical points which have to be taken into consideration Yo facilitate the easy working of the programmes, it was considered necessary to have two studios, one large and one small, with facilities for changing from one to the other instantaneously. To do this, it was necessary to make .certain structural alterations to the building. .As now finished, the control room is placed between the small and large studios and the control operator ‘has an uninterrupted view into both studios through large plate-glass windows. In the control room is placed the amplifying and monitoring equipment, by means of which the control operator has absolute control over the volume level of the signal to ‘the station on the hill, as-well as checking up apparatus for rhe purpose of comparing the actual item as put into the line With the same item as broadcast from the station In the control room also is another panel for selecting the particular :nicrophone in use or for chang ing over for announcements or to outside relays. The necessary: batteries for this apparatus are contained in a small room in another part of the building, together with the charging arrangements. . The sounding properties of the tw studios is a matter which also had to be considered. Yo obtain good quality reproduction, it is necessary to keep down the reverberation ‘time, of the room to about one secoud." Tt must be remembered that reverberation is not echo. A small echo is desirable, as it gives a pleasant ring to ‘he item and is

more in accordance with what a lstener would actually hear if the artis: were performing on the stage of a sage auanolum. Keververasion, however, is more or less persistence o1 small echoes and has to be to a large extent elimmated for best quality. In the case of the studios at 2YA it has been accomphshed by arranging ‘thick felt pads ot predetermined sizes on various parts of the walls, these paus, of course, being covered with a suitable material to harmonise with the scheme of turnishings. In addition to these pads, there are a few curtains suitably placed. Care had to be taken not to overdrape, as otherwise everything would sound dead and unnatural, and yet excessive reverberation had to. be eliminated. ‘The small studio has been treated in a like manner, but the reverberation time. has heen kept dow here to a somewhat greiter extent than in the large studio owmg to the fact that it will be used for an entirely different class of item. l’rom start to finish the utmost attention has been paid to detail in al) parts of the arrangements, both at the studio and at the station, and in conclusion, the writer wishes to express lis indebtedness to various gentlemen and departments which have rendered every assistance, particularly the oflicials of the Post and Telegraph Department, Wellington City Council, and the Public Works Department.