NAEB Newsletter (Apr 1958)

that orginally used. At one time rejections sometimes ran over 90 per cent of the tape supplied' to the user. ^ At present there is only one method of testing the tape and that is by recording a video signal and play¬ ing it back. This practice is recommended when a new reel of tape is received. We used one reel of tape for tests during the week, erasing it manually when the occasion demanded. I saw no evidence of drop¬ outs, which were once the major defect making the tape unfit for use. To enable the tape to be spliced, an “edit” pulse is laid down along the bottom edge of the tape over the control track. These pulses are “developed” by applying a carbonyl iron powder suspended in a volatile fluid to the coated side of the tape. This so¬ lution dries rapidly and the tape is cut by the use of a razor blade, a straight edge and a splicing jig fur¬ nished with the machine. The cut is made parallel with the “swipe” of the head across the tape and on the edit pulse. The edit pulses are timed so that the splice comes during vertical blanking to eliminate picture roll over or noise due to the splice. The pres¬ ent splicing jig is but a milled plate to align the tape so that the cut may be made at the proper angle. We saw an engineering model of a splicer which will be of considerable advantage, where splicing and edit- ing is required. Since the head tips, when new, pro¬ trude less than four mils from the drum, a special splicing tape must be used which is very thin. It also must be applied to the back of the tape without wrinkles since the tolerance between the tape guide and drum is but a few thousandths of an inch. At the time of our visit to Redwood City, over fifty video tape recorders had been produced and the machines were coming out of final test at a rate of one per day. Ampex expects to have its initial pro¬ duction run completed and in the hands of users well in advance of the advent of Daylight Saving Time April 27. Training classes consist of no more than ten students. Ours had an international flavor, with a representative of Siemens-Halske, a German firm which will handle export distribution, an engineer from a Havana station, and representatives from TV stations in Boston, New York, San Antonio, Lubbock, Tex., and Los Angeles, besides the writer. We be¬ lieve it was time well spent. Our only regret is that we will not be able to put the training obtained to immediate use in educational television. ***** The February 1958 RCA Broadcast News contains ^ a comprehensive twenty-six-page article on WTJNC- TV at Chapel Hill, N. C. It is profusely illustrated and has diagrams of the microwave relay system used to connect the studios in Raleigh, Greensboro and Chapel Hill to the transmitter near the latter studio. Audio and video block diagrams are included as well as the video schematic which is common to all studios. The same issue of Broadcast News contains a brief article by A. H. Lind and a block diagram show¬ ing how a color television signal is processed for re¬ cording on a video tape recorder. ***** We see by Radio-TV Daily that WOSU-TV has recently put into service two complete remote units (a total of four cameras) to telecast special events. It is also expected that these units will be used for instructional purposes, either by closed circuit or broadcast on the Ohio State University station WOSU-TV. All of which brings up a point we’ve been wanting to mention for some time. It would be nice to hear from our readers occasion¬ ally and also to be included when publicity releases are sent to the press regarding new equipment or other technical improvements. We’d like to know, too, whether anyone besides Ralph Townsley at Pur¬ due has purchased any of the used image orthicons from NBC which we announced in a December mail¬ ing and also in the January Newsletter. Purdue liked' the first four 5820’s they received so well, they im¬ mediately ordered four more. We do appreciate the notes some of you have written but we’d like to hear from more of you. With 31 ETV stations now on the air it’s difficult to make frequent visits, so drop us a line to tell us of the progress you’re making and pass along any items you think would interest others. ***** The FCC is proposing to add a new section to Part 4 of its rules and regulations to provide for licensing low powered' auxiliary transmitters used to transmit cues and orders to production personnel and participants of broadcast programs. The proposed rules provide for operation in the 26.10 - 26.48 MC and 450 - 451 MC bands. Plate power input to the final rj amplifier is limit¬ ed to one watt. No operator’s license is required of the person actually using these low powered units, provided that a licensed operator is on duty at the place of operation. A Radiotelephone first or sec¬ ond class operator license is required when any ad¬ justments or changes are made which would affect the proper operation of the transmitting units. Call letters will not be assigned, however adequate records must be kept of the periods and place of operation. Comments on this proposal, Docket No. 11696, are due April 15, 1958, with reply comments due ten days later. APRIL, 1958 9