Link: http://wgsf.oldgleaner.com/
The WGSF Television Transmitter
A multi-page post -
Part 1: The Transmitter - At the Heart of WGSF
Most people never see the apparatus that constitutes the final link between the television production system and the receiving audience. The transmitter equipment in most stations is typically located at some remote hilltop site, far from the studio and production controls, or at least tucked into some inaccessible and off-limits room in that mystical realm seen only by the eyes of broadcast engineers and technicians.
The WGSF television station was therefore most unique, in that all the operating controls, including the transmitter, were located in one room. At WGSF, the transmitter and activities of the control operator were right there for everyone to see and experience.
The production control room sat in front of the transmitter, sharing controls in the same console. The announcer could look out from the audio production booth and gaze upon the glowing electronic tubes in that expansive box that occupied most of one wall of the control room. One entry door into the studio took you right past the entire length of the transmitter. The station office shared space with the maze of plumbing behind the transmitter that connected it to the antenna located 410 feet above. Even the rest rooms were just a few steps from the center of operations.
In addition to controlling the parameters of the transmitter’s ‘behavior,’ the duty operator was also responsible for programming, that is, switching from program source to program source as listed on the broadcast schedule, controlling the appropriate video or audio recorder, film chain, or network and pre-loading fifilms, slides, and tapes. The transmitter, therefore, was essentially the heart and soul of the entire operation.
It was a special challenge for student staffers to operate station breaks, under the watchful eye of the duty operator.
I dare say that no person in television broadcasting other than Leland Hubbell has had the experience of leaving the host’s chair in the studio in the middle of a live broadcast, replacing a failed audio final transmitting tube, then returning to the studio to finish the broadcast. Only at WGSF!
Written by Leland Hubbell
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Part 2: Pulling Transmitter Duty
The Federal Communications Commission (FCC) required that a person holding a valid FCC “First Class Radiotelephone” license be at the controls of a broadcast transmitter during the years WGSF was broadcasting. (Those rules have since been modified.)
Passing the required FCC exams, then posting the crucial license at the transmitter is indeed a proud moment for all who seek such status.
Obtaining the “1st Phone Ticket” made one a member of a select group, signifying the successful passage of a series of challenging examinations from the FCC. The licensing requirement also meant that a very limited pool of people were available for employment as a transmitter operator. Several of WGSF’s operators either came through the electronics programs at the Newark Air Force Station, or worked there as their primary job.
Although there was a certain challenge to it, transmitter duty could be described as hours of tedium and boredom interspersed by moments of pure panic!
WGSF had a turn-on and turn-off routine. The engineer would first switch electrical power on to the equpment at the main electrical control panel behind the transmitter. The transmitter would be switched to “standby” or warm-up status to avoid sudden electrical stress to the expensive transmitting tubes. The auxillary equipment would be checked, and the sign-on tapes and slides would be loaded and previewed. After a few minutes of warm up, the actual broadcast mode would be activated, first at low power, and gradually increased to full operating licensed power. A slide with a test pattern and station identification was broadcast on the visual transmitter, and a test tone of 600 hertz frequency on the aural, which provided standard signals to evaluate the transmitter’s performance. At sign-off, the broadcast power units were first turned off, and the system allowed to cool down gradually, again to minimize stress to those expensive transmitting tubes.
Broadcast stations are required to keep both a record, called a log, of all programs and announcements broadcast, and a technical record for the transmitter itself. It was the custom at WGSF to take a complete set of meter readings on the hour, and a short check of operating power and channel frequency on the half-hour. The power and frequency readings were the critical ones, required by the FCC, but the other operating parameters were essential at times for the maintenance engineer to evaluate when it was necessary to make critical adjustments or change tubes. Advancements in technology have brought automation, remote and computer control to transmitter operation. The FCC rules have been changed accordingly. That was never an option for WGSF.
The first years of operation were the really lonely ones.
Robert Brooks, the first paid employee, kept a hand-written Program Log (A listing of programs broadcast, Announcements, Station Identification, times, etc.), plus the Transmitter Log. Except for the Station ID (Call letters, visual and aural) - all programming came off-air from WOSU-TV, Channel 34, in Columbus, Ohio.
WGSF broadcast only on weekday evenings from March 18, 1963, until September of 1964.
WGSF started broadcasting daytime school instructional programs in the fall of 1964. Leland Hubbell, who replaced Robert Brooks as Chief Engineer, would come in for the morning sign-on, and stay until the school schedule ended in the afternoon. The station signed off, and the operator went home. Wayne Gehres then came in, signed on, and worked the weekday evening shift until sign-off.
Most days, the operator would not see another person, or even have a telephone call the entire shift. The only person other than the operating engineers to routinely visit the station on Horn’s Hill was WGSF station General Manager, E. Dana Cox, Jr., who would bring up the program log and perhaps make the announcement tape. His visits often occurred during the gap between the daytime and evening schedules, and neither engineer would even see him.
Allan Smith served as the Sunday transmitter Engineer for many years. Sheri Short took over the daytime shift. Several engineers shared the mid-afternoon shift, including Irv Brown, John Gross, and Charles Cohen.
Except for four locally originated programs broadcast in the spring of 1963, there was no television production to bring anyone else to WGSF for three long years.
Things picked up with the advent of local production in 1966. Still, periods of solitary vigil remained, especially during weekends,.
A salute to the transmitter engineers who sat at their sometimes lonely operating post atop Horn’s Hill, in Newark, Ohio.
December 24, 2007 by Leland Hubbell
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Built by the General Electric Company, the transmitter was designed in the early days of UHF television broadcasting. The WGSF equipment consisted of three cabinets, and was sort of like a Siamese twin. There were actually two transmitters, one for the sound (aural) and one for the picture (visual) broadcast information, joined in the middle by a unit common to both. The visual circuitry, the more complex part, was located on the left side of the transmitter, and the aural to the right, viewed from the control position in front of the transmitter.
The larger, central unit contained the devices to establish the operating channels, and generated both the picture (visual) and sound (aural) carriers of the broadcast signal and ‘modulated’ them with the respective sound or picture information. The low powered 100 watts level signals out of the central cabinet went to the ‘final amplifier cabinets where they were boosted to licensed broadcast strength (1000 watts, visual, 600 watts aural) - one on either side of the central unit.
There was a maze of plumbing behind the transmitter. The respective audio and visual signals were filtered to remove frequencies that might be outside of the assigned broadcast channel, and combined by a device called a "Filtrexer" (filter/multiplexer) onto one transmission line (big copper pipe!) that went up to the antenna at the top of the tower.
Parts of the system used at WGSF, like the Filtrexer, were essentially overkill, as they were designed and rated for much more powerful transmitters that required as much as ten times or more the ratings that WGSF needed, but again, WGSF used whatever was available.
The main duty for the transmitter operator was getting the transmitter on the air, and keeping it there. Getting the box on the air, and keeping it there were two different ball games, however. All of those meters on the transmitter and related monitoring equipment told the operator something about how the transmitter was performing, for better or for worse. The transmitter operator or engineer maintained a record, or log, of the various operating parameters, according to FCC rules and regulations. The settings that kept the transmissions at the proper channel frequencies and output power were cautiously observed, accordingly noted on the log, and adjustments were made if needed.
The FCC (Federal Communications Commission) Rules and Regulations not only assign the frequency (channel) on which a station operates, but also proscribes limits as to how close to those standards one must stay. It was not always easy to keep the WGSF transmitter spot-on. The transmitted power would drift up and down depending upon the voltage supplied by the electric company, usually dropping as the big industrial users came on-line during the day, and soaring in the non-working hours. There was a switch on the central cabinet of the transmitter to boost or reduce the power - within limits. When the big transmitting tubes reached their age limits, it was hard to make minimum power. Temperature also affected both the power and the frequency of operation.
One required monitor displayed the operating frequency of the Aural and Visual transmitters, and the Aural modulation levels.
The device we used at the station to monitor the frequency sometimes drifted off accuracy itself, giving us a false reading, and a possible citation for illegal operation. WGSF used an HP-335 monitor. (See next page) Both the transmitter and the monitor had to be adjusted periodically to stay within legal specifications. The station subscribed to a monitoring service, so we got a monthly frequency accuracy check from Woodward Labs, a company in Mt. Vernon, on retainer for that purpose. Those readings were also logged by the operator, noting any deviation above or below the assigned channel. The monthly report was noted in the transmitting log, and kept on file. Adjustments were made if needed - and they usually were.
Until colorization,WGSF was only authorized to broadcast in monochrome (black and white. )There was a circuit in the transmitter video modulator which was supposed to delete the color information from the picture, but some people reported that they sometimes still received network programs with color. We had no way of knowing; WGSF had no equipment for checking for a color picture (Not even a color-capable television) until after receiving the color equipment.
All of the original equipment at television station WGSF used vacuum tubes - lots of vacuum tubes. Vacuum tubes wear out: their performance drops over time, or they even short out entirely. Most of the test equipment owned by the station when it initially went on the air was from a radio/TV repair shop that was bought out. The device used to test vacuum tubes was essentially for home type electronics, but covered most of the common tubes used in the WGSF equipment, but still mostly "go/no go" readings. The purchase of a more industrial oriented model made the task of preventative maintenance both easier and more accurate. Every tube was checked on a periodic basis, and the readings kept in a database.
Most vacuum tubes used at the station could be purchased locally from an electronics supply store, the same place the radio and TV repair shops bought theirs. The major transmitting tubes, the power amplifiers, or ‘finals,’ were made only by General Electric, cost over a thousand dollars, and had to be obtained from a dealer of industrial tubes in Columbus, OH. We babied those beasties, and kept a special card under a serial number on file for each one.
WGSF followed a special turn-on routine for the transmitter, starting at reduced power, and gradually increasing to the normal operating power. The transmitter also had special circuitry designed to ease the tube up to normal parameters, so as not to damage the ‘heater’ or ‘filament’ in the tube. Still, most of the power tubes didn’t just wear out; they would die of an open filament, burning out like a light bulb, their distant cousins. They could also sustain an internal short between elements, no matter how carefully we watched over them. Still, some of the specialized transmitting tubes could not be checked, except by the operating readings monitored and indicated by the meters on the transmitter itself. Thus the chore of taking and recording an hourly set of readings had a practical aspect besides meeting FCC rules and regulations. The maintenance technicians could note the performance of those tubes, and replace them when necessary.
Broadcast signals must conform to very stringent standards. Meeting those standards was always a challenge at WGSF.
Changing any tube in the radio frequency chain that generated the broadcast signal necessitated retuning the amplifier stage. The aural transmitter was fairly straightforward, and generally required only a minimum of attention.
The visual section was literally a nightmare! The visual transmitter required a tuning process called ‘broadbanding.” That meant that more than a dozen adjustment points had an impact on the proper overall performance. Further, WGSF never had the proper test equipment, a ‘sweep generator’ and sideband analyzer that would trace a picture of the bandpass on an oscilloscope screen. Initially, the station had one oscilloscope to display a video signal, a Tektronix model 524 AD on a ‘Scopemobile.’ It doubled as test equipment for any video signal work. Eventually, a dedicated oscilloscope monitor for the transmitter was obtained.
All sorts of things could go wrong to distort the picture in some way, and often did. There were about 15 adjustments, any of which had the ability to really mess up everything else. It was a frustrating task, since WGSF never had all the proper equipment to make accurate adjustments. Replacing a critical tube could take hours and hours of fiddling to get things right again. The visual modulator never did operate exactly as designed, and was at best of times rather frustrating to keep within specifications.
Trying to tune that thing properly was about like trying to get the toothpaste back into a squashed tube. Squeeze that tooth paste tube here, you get a dip. Squeeze another place, that dip changes, but you get another dip. Pretty soon you no longer have the nice, smooth tube that you started with. Now multiply that to the square of 12 - or more. That’s what it was like to tune the visual transmitter without the proper test equipment. Pretty much “by guess and by golly!”
Add to that the device that put the picture information on the radio frequency carrier. The video modulator was maddening. It never worked as designed, ever. It nearly drove GE’s own engineer to total despair during the conversion from channel 28 to channel 31. He would get on the telephone to the guys in the engineering department back at GE, mumbling things uncomplimentary about the modulator. He came to hate a particular, though essential, piece of test equipment. It would simulate a picture change from total white to total black. The meters on the transmitter would flip wildly, the protective circuitry would kick in with a ‘klunk,’ and kick the whole box off the air. Over and over! Yes, he despised both the modulator and the standards that it would not - could not - attain.
There were certain vacuum tubes in the modulator that could be pulled from their supposedly ‘normal’ locations and placed in sockets labeled “Emergency Operation. “ Every transmission at WGSF was an “Emergency Operation.
The Chief Engineer also took care of major maintenance, not only on the transmitter, but on most of the rest of the equipment as well. In later years, some of the technical staff had the expertise to deal with minor repairs, but the transmitter went above and beyond ‘normal,’ requiring expertise with high power radio frequency equipment, and of course the FCC First Class Radiotelephone License. Each station is required to do a thorough testing of all broadcast systems, called a “Proof Of Performance.” This was done by an outside company before the station first went on the air in 1963, when the station changed from channel 28 to channel 31, and again when the transmitter was ‘colorized;” that is, it was equipped and certified to handle color programming.
Written by Leland Hubbell
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The HP 335 modulation monitor provided the visual and aural carrier frequency monitoring. I don’t think I visited a transmitter that didn’t have one for many, many years. Even if they had a later unit, most places kept the HP also. Actually we did have the Marconi sideband analyzer that was provided by the State after the colorization. I know Jeff (Campbell, WGSF Engineer) felt he never did quite master the unit, though it apparently had some advantages over a general purpose spectrum analyzer and a sweep generator. It was at the bottom of the left hand rack that we added for the color conversion. The scope used to monitor the visual modulation was the Tektronix 529. The important thing was learning to use the zero carrier pulse to generate a reference point and then remember that we actually looked at the modulation upside down: the higher the waveform got the less the modulation. We had one color monitor, a Ball-Miratel 12 inch unit, to see how we looked in color. The Tektronix 144 and 147 test generators the State provided made us the envy of a lot of stations that were still using first and second generation test generators. Even when I got to WBNS, they were still using a Riker solid state test generator at the transmitter and a tube type test generator down in master (control.) There was a Tek 144 making bars into the router. When we got the direct PBS microwave feed the color certainly started looking better. The color programming that we got off air from WOSU was somewhat impaired. The other piece of modern test gear we had was a Tek 453 oscilloscope that we used in place of the 524 and even took on remotes and minimotes when necessary. The odd thing about that scope was that one channel occasionally acted up. If you banged on it, it would be fine for a while. I accidentally found the problem a year or so after we got the scope. One end of the resistor connecting the input connector to the circuit board had never been soldered at the factory.
The Hickok tube tester with the built in roll chart listing the tubes was actually a lot of fun for the first 20-25 tubes. After that it got tedious.
You mentioned the GE engineer, Sabeff, who disliked the modulator so much. Do you remember his comment one evening when he got disgusted with the progress he was making? And do you remember asking WCLT to shut down their transmitter long enough to confirm that the birdie he was chasing wasn’t an external signal? He was amazed when he walked in and saw the iconoscope (camera chain) still operating. Do you remember where he’d last seen one working? (Brazil)
You didn’t mention the pretty blue glow of the mercury rectifier tubes. Imagine the EPA permits you’d need today to run those tubes.
Daniel
Part 3 From Daniel Black
Sign Off
The transmitter was turned off for the last time on June 30, 1976. The transmission line, the 3 1/2 inch copper pipe leading up to the antenna, was switched over to the new translator that was installed and operated by the Ohio ETV Network Commission. The new box operated on the same channel as WGSF, Channel 31, and at the same power. The station, however, was quiet, except for the hum of the new unit as it automatically turned on when WOSU-TV, Channel 34 in Columbus, began their broadcast day on July 1, 1976.
The Federal Communications Commission was accordingly notified, WGSF's license to broadcast was canceled. The WGSF transmitter sat dark and cold, never to be turned on again.
The school district, owner of the station, had one query with intent to purchase the transmitter, but no further response occurred once the technical information was sent to them.
The city and county use the WGSF tower for their two-way radio antennas. The equipment, which was housed in a room in the south east corner of the building. They requested permission to utilize the now unneeded space, stripped of all but the old transmitter, to install additional equipment for their communication services. Permission was granted to the local amateur radio club, who had moved their amateur repeater equipment into the former WGSF audio production room, to dismantle the transmitter. None of the former WGSF staff was there to witness that final phase of the history of WGSF.
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03:31:48 am, by admin 
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