Broadcasting (July - Dec 1942)

Maintaining Broadcast Operations in War Ingenuity in Utilizing All Available Material Required in Canada By J. A. OUIMET Assistant Chief Engineer, Canadian Broadcasting Corp. Outside of winning the war itself, no subject is closer to the heart of. the American broadcaster than the problem of plant maintenance under wartime rest7-ictions. Broadcasting has published two noteworthy contributions on the subject recently — one, excerpting some of the Canadian experiences as related at in Army work, in the March 9 edition; the other by Charles H. Singer, WOR technical supervisor, now also with the Army, in the March 30 edition. We urged then that every manager require his technical staff to study the articles intently, and this one, excerpting some of the Canadian experiences as related at the Cleveland IRE convention this week, should also be read with the thought of profiting by experience. FOR THE CBC the problem of maintaining its operations in wartime is essentially the same as that which faces American broadcasters. It is con fronted with the same serious economic difficulties, with the same dangers of sabotage, and finally with the same possibilities of enemy action which may bring Mr. Ouimet about the destruction of its facilities. With 10,000 miles of transmission lines operating through five time zones, the CBC network extends from Sydney, N. S., to Vancouver in B. C. and links together a total of 57 stations. To man these facilities a technical staff of more than 150 is maintained, exclusive of the engineering personnel of its headquarters in Montreal. The first wartime measures were introduced right at the start of the war, in the fall of 1939, and were directed against possible sabotage. These included the construction of barbed wire fences, the installation of flood lights, the erection of sand bag barricades, and finally the establishment of armed guards at all main outside plants. Sand Barricades To protect vital parts against destruction by explosive projectiles that may be directed from outside of the fenced enclosure, sand barricades have been erected around the guy anchors and at the base insulator of all vertical radiators. The same precaution is also taken for the outside power substations and in front of certain sections of the transmitter buildings such as the large glass brick section of the transmitter at Vercheres. It may be interesting to note that sand bags are not used here but loose sand between wooden supports. This construction is in sections so that damage to one part of the structure will not cause all the sand to pour out, rendering the whole barricade useless. It was learned by experience early in the game that sand bags are not suited to long exposure to Canadian climatic conditions, all the sand bag barricades that were originally installed having collapsed within 12 months, due to rotting of the bags. Protection against sabotage is, of course, only a small part of the measures we have had to take. The situation in Canada with regard to sabotage of equipment and difficulties of procurement are just as serious as in the USA and perhaps even more so, since practically all the major radio parts and transmitter tubes used in Canada have to be purchased from American manufacturers. As a contribution towards the solution of the general problem of equipment shortage and as the surest way of insuring the continuity of service, the engineers of the CBC are now concentrating their energies in an extensive conservation program. The CBC is taking every possible means to keep its operators, as well as members of other departments, constantly "conservation conscious". War Manual The backbone of this conservation drive is a sort of war emergency manual which is distributed to all who handle equipment. This manual outlines the facts of the problem and indicates practical ways of meeting it. This has been prepared in loose-leaf form so that sections can be modified or added with ease. This is supplemented by releases from Engineering Hdqrs. designed to keep the interest of the staff in conservation matters constantly alive. The material for these releases is generally taken from news items or from articles in newspapers and magazines which provide some striking examples of shortage difficulties or of particularly interesting ways of meeting them. An accurate inventory has been made of all CBC facilities, spare parts, expendables, and even of so called "junk piles" as a preliminary step towards redistribution if necessary. With the number of plants operated by the CBC this is an equivalent, within one organization, of the idea of "pooling of equipment" which is being considered by American broadcasters and under this plan the spares of any one of the CBC stations can be shipped at a moment's notice to any other CBC plant which may be in difficulty. To conserve high-quality microphones, restrictions have been made to limit the number of microphones to be used on any one program. This last measure should actually improve the quality of programs since good engineering indicates the use of as few microphones as possible. Similarly, for turntables and reproducers all high-quality units are used only where the higher performance can actually be appreciated and they have been replaced with the cheaper types for such work as sound effects, auditions, etc. In addition, a survey has been made of all so-called obsolete equipment, and antiquated amplifiers, which have been discarded on account of high noise level, etc., and when needed, these units will be rejuvenated by minor changes in tube types and circuits. Cut in Power Output But perhaps the most important contribution that broadcastingcould make towards conservation of tubes and equipment would be to actually reduce the power output of broadcast stations. A 20% power reduction might double the life of tubes and yet hardly affect the service to the listener. The CBC engineers are convinced of the advisability of this measure and have already taken active steps towards its application in recommending its adoption to the Canadian Radio Administration. Pending official decision the necessary simple modifications to the control and protective circuits have been made at all CBC stations to switch over to reduced power operation without delay as soon as permission is granted. Tests that have already been made show that many tubes that had to be taken out of service as unable to deliver full power can give many more hours of useful life in operation with reduced power output. To counteract the inevitable degradation of operating standards as inexperienced staffs gradually replace fully qualified personnel, an extensive educational program has been established to give the necessary theoretical background to the newscomers as well as to refresh the knowledge of the regular men who have been able to remain. These advantages are available to the office staff in the hope of developing a trained reserve. There are three other methods by LARGE-SIZE HALO above head of M. W. Scheldorf, GE radio transmitter engineer, in upper picture is a new type FM antenna he has developed. It was displayed at the Institute of Radio Engineers summer convention July 1 in Cleveland and is said to simplify radiation of radio waves in all directions horizontally. New motif in antennas for automobiles of the future is displayed by Mr. Scheldorf in lower picture. This can be installed a short dis, tance above the roof of automobile:., it was said, and will provide tht same operation secured from buggywhip antennas used today. The toy locomotive was merely a prop. which the effect of fire and sabotage losses can be minimized should they occur in spite of these precautions. These are the dispersion of facilities, the provision of standby or emergency facilities, and finally the prearrangement of facilities and operations in such a way as to allow readily the shifting of operations from one point to another if necessary. Emergency Aerials At transmitters, to meet the possibility of destruction of the regular antennae, emergency aerials will be installed at all transmitters. Having already lost one of our aerials in a gale, the 525-ft. radiator of CBM near Montreal, the CBC engineers have practical experience in the subject of antenna losses. These emergency antennae are simple, inexpensive, and designed to save material as much as possible. They have come to the conclusion that a simple structure of the L or T type with 80 foot masts is adequate. On a frequency of 1070 kc. calculations give a field strength of 158 mv/kw at a mile and this is enough for emergency operation. Such an antenna costs only $1,000 complete. A similar structure with masts of 150 feet would cost twice {Continued on page H) Page 20 • July 6, 1942 BROADCASTING • Broadcast Advertising