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by F. F. BATEMAN Technical Operations Manager, WBTV

Recently WBTV logged its 5.OOOth hour of RCA television tape recorder operation from its studios at "One Julian Place" in Charlotte, North Carolina. *1)

• *1) Editor's Note: WBTV installed its first television tape recorder in September of 1958 when it took delivery of one of the seven preproduction models of the recorder (also Labormuster) built by RCA. This recorder was in extensive use in on-the-air programming at WBTV until June of 1959 when it was replaced by a production model.

The first RCA production television tape recorder, TRT-1AC, was received at this station May 22, 1959 and put in service on the same date.

The second production model television tape recorder, TRT-1AC, was received and put in service on October 4, 1959. Both recorders are in extensive use in day-to-day studio operations at the present time.

During these first 5.000 hours, WBTV has been getting excellent headwheel life. In our two present machines, we have averaged 348 hours on headwheels which have run to the normal end of life.

The average life of all headwheel assemblies used (including those taken out of service because of mechanical defects, etc.) has averaged 238 hours per unit. To date, seven separate headwheel assemblies have racked up over 300 hours each.

• Anmerkung : Als es 1956/57 mit den Quadruplex Kopfrädern anfing, wurde die "Standzeit" für die anfängliche Studioquelität von Ampex mit ca 150 Stunden (s/w) angegeben. Danach wurde das Bild zusehends schlechter. Die oben genannte durchschnittliche Standzeit eines Kopfrades bis zur Aussonderung von 238 Stunden ist sehr schön- gerechnet. Diese Standzeiten / Laufzeiten wurden bei unseren Sendern nie erreicht, vielleicht weil bei uns die Ansprüche einfach deutlich höher lagen. Meine Erinnerungen an den Fernsehabend 1985 im größten Hotel in Carson City sind nur an dem damals schlechten Farbbild im Kopf hängen geblieben.

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How does WBTV get such good life from the headwheel assemblies in use here? We believe that this is due primarily to the fact that one man has been given responsibility for operation and maintenance of the television tape recorders since the first machine was installed.

This man is on a daytime shift. He does the bulk of the tape recording, and during the time the machines are not in use, his time is spent in preventive maintenance.

Presently, all our technical operations personnel are checked out on use of the tape machines, but one man continues to have primary responsibility for the condition of the equipment.

The man chosen for this particular job must be one who has a feeling of responsibility, who understands and respects the equipment, and has the initiative required to accomplish adequate preventive maintenance.

This, of course, involves tube checking on a fairly routine basis and continual close observation of the equipment while in normal operation.

• Anmerkung : Die Überprüfung der Röhren hat mit der Lebensdauer des Quadruplex Kopfrades nicht das Geringste zu tun.

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Cleanliness is also important in obtaining satisfactory head life. The television tape recorders at WBTV are installed in an air-conditioned room which helps keep dust problems at a minimum. The operator cleans the headwheel and vacuum guide assembly each time a half-hour or hour tape is played on the machine, and he also takes care to clean lint from the air intake around the edges of the headwheel motor where the cooling air enters.
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Since roughly 90% of the taping we do is for our own use in-the-house, we have established a dual-standard operation in regard to tip penetration on recording.

When taping for shipment out of the station, or for keeping indefinitely, we follow the proposed SMPTE standard of operation.

The eccentricity between the vacuum guide's center of curvature and the headwheel axis of rotation has a value of 0.0003 inches, and tip penetration is set approximately equal to headwheel tip protrusion. This condition is determined by use of the RCA M1-407 71 test tape.

We keep the hours of use fairly well balanced between the two machines, which means that the two headwheel assemblies are continually accumulating about the same number of hours total wear.

This allows us, when taping for in-the-house playback within a few days, to limit tip penetration on recording to 2 mils beyond the drop-out point (as long as the head-wheel tip protrusion exceeds 2 mils).

Naturally, when the headwheel tip protrusion has worn down to 2 mils, our in-the-house recording is done from then on according to the proposed SMPTE standard.

While most of our tape operation does not involve tip penetration over about 2 mils, all tapes made for outside use or for indefinite storage are fully compatible with the proposed SMPTE standards. We feel this philosophy of operation contributes materially to our good headwheel life record.
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In summary, it would seem that the good headwheel life obtained at this station is due first, to the assignment of one particular man of high qualifications to operation and maintenance of the recorder; second, to cleanliness in operation and maintenance of the equipment; and, third, to use of minimum necessary tip penetration when recording.

The RCA television tape recorders which have been in use here for over two years have proved to be extremely dependable and reliable in operation. There has been, of course, the normal amount of maintenance to be expected from such a piece of electronic equipment.

However, the basic design of the television tape recorder has proved itself in our day-to-day operations.

FIG. 1. The author : Frank Bateman inspects one of the tv tape headwheel panels. In 5.000 hours of operation. WBTV has averaged 238 hours per panel, including those still in service. Seven separate headwheel panels have racked up over 300 hours each.
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