NAEB Engineering Newsletter (June 1957)

AEB ms Engineering Newsletter NATIONAL ASSOCIATION OF EDUCATIONAL BROADCASTERS 14 GREGORY HALL JUNE, 1957 URBANA, ILLINOIS TV TECHNICAL TIPS NO. 31 —By Cecil S. Bidlack, NAEB TV Engineer This column is being written on the road in order to meet the deadline. It seems each month the deadline dates move closer together. Perhaps it is because it takes a while to get the Newsletter into print, and by the time it’s out, copy for the next one is due. * * * * I have been honored by membership on Panel 4 (Propagation Data) of the TV Allocations Study Or¬ ganization. TASO’s function is limited to technical study, fact finding and investigation, and interpreta¬ tion of technical data. This information will be made available to the FCC so the Commission may be able to determine the soundest approach to TV channel allocations. Panel 4 held its first meeting in Washing¬ ton on March 13, with 20 of the 26 members present. The standardization of field strength measure¬ ments is one of the first objectives under study by the panel. The Association of Maximum Service Tele¬ casters now has two mobile field strength measuring units in operation. Two other units, a CBS unit and a Westinghouse unit, will soon be in the field. UHF transmission is also of primary concern; however, VHF measurements are also needed over different types of terrain. Please contact me if you have field strength data available. * * * * The Institute of Radio Engineers held its annual Convention in New York March 18-21. Fifty-five technical sessions were held during this period, rang¬ ing in topics from airborne radar to ultrasonics. The radio engineering show filled four floors of the New York Coliseum with 840 exhibitors taking part. From an organization of radio engineers having its beginning in 1912, the IRE now has grown to ^ 55,494 members. Due to this growth, 24 professional groups have been formed which cover specialized fields of interest. For instance, most radio and TV engineers will be found in the Professional Group on NAEB Engineering Newsletter June, 1957 NAEB Engineering Newsletter, a quarterly publication issued by the National Association of Educational Broad¬ casters, 14 Gregory Hall, Urbana, III., $2 a year, edited by Cecil S. Bidlack. Application for 2nd class mail privileges pending at Urbana, Illinois. Broadcast Transmission Systems. TV TECHNICAL TIPS NO. 32 I finally made it—to Minneapolis, that is—and the home of KUOM, NAEB President Burton Paulu, and KTCA. In addition to participating on a panel on the “Use of Closed Circuit TV by Schools” at the Central State Speech Association Conference April 5, I was able to take a look at the facilities of KUOM and KTCA. KUOM occupies the 1st floor of Eddy Hall on the main campus of the University of Minnesota. Every square foot of this space is being utilized to provide offices, three studios (one of which also serves as a TV studio), a combination video control and recording room, and a master radio control room. They are presently converting their trans¬ mitter to remote control operation. We believe many ETV stations could benefit by the procedures used by KUOM for checking and aging miniature tubes used in TV equipment. Upon receipt, KUOM checks each new receiving tube on a mutual conductance type checker. Those which give a sub-normal mutual conductance reading or show other defects are immediately returned to the jobber for replacement. In some instances as high as 20 per cent of the tubes received have been returned. The tubes which pass this first test are then aged with rated voltages applied for 24 hours. A special aging device has been constructed which will age 24 tubes at a time. A plug and jack arrange¬ ment permits the application of appropriate voltages to the tube elements. 1