NAEB Engineering Newsletter (December 1, 1957)

program was being recorded. Four kinescope recorders (two 16 and two 35 mm.), two magnetic sound re¬ corders and an optical recorder were used. No doubt a videotape copy was being made too, but that facili¬ ty is located some distance away from the kine room. The same use of a “protection” copy is made on playback. I saw a videotape recording on the air backed up by a 35 mm. kinescope recording. They just don’t take a chance of losing a program on the air - it costs them money. Of course I realize that ETV stations don’t have the funds or the personnel which are necessary for this type of operation. However, it does point up the fact that 100% reliability is difficult to achieve unless some such procedure is followed. ***** Another operating practice which ETV stations can, and which many of you I hope are following, is that of showing “ corners” on your image orthicons. If you’re using second-hand camera tubes, then I realize you’re limited because of previous scanning. But if you’re using new tubes, don’t be afraid to overscan them on the air. I was surprised to see “big, fat corners” showing on the live monitors which ob¬ viously had to be adjusted to show the entire raster. I was informed that this is standard operating procedure. By following such a procedure, you get increased operating life, increased resolution because you are using more of the target, and if deflection drifts, the video control operator is aware of it. Yet, I have visited stations where there was no monitor adjusted so that the entire raster could be seen and no corners could be seen on the camera viewfinders. Consequent¬ ly, no one knew how much they were underscanning the target. ***** For these NAEB stations who have Magnecord PT6-A and PT6-J magnetic tape recorder combina¬ tions, factory modification information is now avail¬ able which will bring these machines to conformity with those having NARTB approved response. The changes are simple for those PT6-J amplifiers that in¬ corporate the 5881 output tubes and a 5879 input tube. We’ll be glad to supply Thermofax copies upon request; or you can get the original by writing to Mr. Hugh J. Daly, General Sales Manager, Magnecord, Inc., 1101 South Kilbourn Ave., Chicago 24, Illinois. The schematic is on 8% x 11 paper which makes some component values a bit hard to read on our copy. Necessary modifications for the PT 63-J and PT 6-BN will be made available later. A search through the files of these columns fails to disclose mention of an article in the SMPTE Journal for February 1955, “A Short History of Television Recording” by Albert Abramson. It con¬ tains an excellent bibliography on television recording. On writing to Mr. Abramson for permission to re¬ print his article, we discovered that the material it contains is taken from his Electronic Motion Pic¬ tures, published late in 1955 by the University of California Press. We suggest this book as recom¬ mended reading for any television engineer, for it is really a history of the television camera and con¬ tains a very complete bibliography on the develop¬ ment of television equipment and processes. We had the opportunity of meeting Mr. Abramson who is employed by CBS-Television in Hollywood. He graciously conducted Merlyn Rawson and me on a very complete tour of the CBS Television facilities. ***** “Is Portable Test Equipment Portable?” is the title of a short article in September 1957 Electronic Industries and Tele-Tech. It’s a summary of a cur¬ rent test equipment study being conducted at the U.S. Navy Electronics Laboratory in San Diego. The military services have found that technicians fre¬ quently will not use certain items of test equipment simply because they are too large and bulky to carry easily. The factors of weight, width, height and length were investigated. On the basis of this investigation, the maximum acceptable dimensions have been set at 8 inches wide, 18 inches by 18 inches long with a maximum acceptable weight of 14 pounds. It’s good to know someone is making a study to determine what portable really means. Maybe this study will help break down the usual criterion of portability - “it has handles.” Much has been done in recent years to improve the design of radio and television equipment for field use. We can remember the old radio days when amplifiers, mixers and volume indicator meters were built as units on iron panels with audio transformers encased in iron cases and then packaged in oak cases an inch thick. Those too, were the days of battery operated amplifiers where you lugged a 6-volt A battery and 180 volts of B battery, also in a sturdy oak case, to the top of the stadium. The present-day engineer can carry his transis¬ torized amplifier and the rest of his equipment in a camera gadget bag or briefcase, ride to the heated press box in an elevator, plug the amplifier into the AC line, attach the broadcast line and he’s ready to 2 ENGINEERING NEWSLETTER