A NOVEL USE FOR WIRELESS-EQUIPPED VANS.
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A Fleet of Vulcan Vans Engaged on a Special Class of Work.
GRAHAM AMPLION, LTD., 2526, Savile Row, London, W.1, which, as is well known, manufactures electrical equipment and various wireless appliances, has recently put into ,service a fleet of Vulcan vans fitted with Amplion public-speech and band-repeater equipment, and the company antici
pates that in order to cope with the increasing installations of Amplion equipment, the number of machines employed for this specific purpose will be greatly augmented during the coming months. We reproduce on this page a picture of one of the vans which is attached to the company's Manchester branch, and a description of its equipment will serve to give a good indication of the all-round usefulness of the motor vehicle in connection with this branch of the company's activities. Although, outwardly, the body is of conventional build, its interior equipment is specially arranged and so designed that plenty of spaceis available for carrying amplifiers and other wireless equipment. Accumulators are housed on sPecial racks below wide shelves which carry the amplifiers, and they stand on acid-resisting trays which, in turn, are mounted on sponge rubber, so that the effects of vibration are
satisfactorily damped ottt. Glasscelled accumulators are used, each
being contained in a crate that can be nested on others. By following this procedure every available inch of space is utilized to the best advantage, and the weight is evenly distributed over the chassis. The roof is fitted at the corners With triangular metal plates to which are bolted brackets to hold a number of Amplion public-speech horn-type loud speakers. Installations, of course, vary considerably both in size and in character. Sometimes it is possible to make use of the van complete, with its loud speakers on the roof, as a compact unit that can stand in one position and form not only a control room, but also a relay point. In other instances the van is used purely as a control room, and wires are run from it to the loud speakers, which can be Mounted on poles or suitable trees and lamp-posts. •
In the case of an installation having four loud speakers only, use is made of a Minor amplifier, which is of the five-valve, four-stage, two-output type, and ,which uses six volts low-tension and 288 volts high-tension. In the case of an eight loudspeaker installation, the five-valve Minor amplifier is used as the microphone amplifier, and this is followed by a WW amplifier utilizing four valves, one-stage, four outputs; this consumes 12 volts low-tension and 648 high-tension. When an even bigger installation using 32 loud speakers is employed, the apparatus consists of a Minor amplifier followed by two eightvalve, one-stage, eight-output ampli. tiers. These make use of a total of 30 volts low-tension and 1,008 hightension. For equipments of greater capacity than those mentioned, it is only necessary to add further amplifiers, but it is usually found that a 32-loud-speaker installation is Sufficient to cover all normal requiremeats. In all cases it is possible to house the complete apparatus in the van.
As our picture clearly shows, the driver's cab is totally enclosed (its doors have drop windows) and it makes an excellent " studio " from which announcements can be made, whilst music may be obtained from a gramophone record by means of an Amplion patent gramophone transmitter. The change from speech to music and viceversa is extremely simple to carry out, a special switch which is incorporated in all Minor amplifiers being employed for the purpose. The body of -the van which we illustrate was built by Glover, Webb and Liversidge, Ltd., and the vehicle is shod with Goodrich pneumatic tyres of 34-in. by 7-in. dimensions. The interesting model fitted to the radiator filler-cap should be noted.