Grand Rapids station uses RCA 50-Kw transmitter and 12 bay antenna for 25,000 square mile coverage
Source: RCA Broadcast News, November 1962
Author: Bruce M. Glycadgis, Chief Engineer
To the people of Western Michigan "FM" means WJEF-FM with true FM quality service with power. For twenty-one hours each day, WJEF-FM radiates its stentorian voice of 500,000 watts (ERP). WJEF-FM began broadcasting with one-half-million watts (ERP) November 15, 1961. It was a great day for FM listeners within the reach of its signal because it meant that all could receive noise-free programming whether they owned small receivers, large receivers, cheap receivers or expensive receivers...whether they had or did not have antennas. It brought on a great resurgence in the purchase of FM receivers within the area this signal reaches, especially in areas that had never before heard FM. But, in reality, this was not the beginning but merely the ending of a great struggle to bring powerful quality-FM broadcasting to the listening public of Western Michigan.
The Beginnings of WJEF-FM
The birth of WJEF-FM goes back nearly seventeen years ago to 1946. It was during 1946 that the Fetzer Broadcasting Company obtained its first construction permit for WJEF-FM. This CP was for the, in those days, unheard-of power of 500,000 watts (ERP). The company was immediately confronted with many complications arising from the fact that equipment capable of producing 500,000 watts (ERP) such as the "RCA 50 kw Transmitter" and "RCA 12-Section High-Gain Antenna" were not readily obtainable. There was also the problem of obtaining a suitable antenna site with adequate ac power available for such a powerful transmitting plant.
In 1950, the Fetzer Broadcasting Company constructed WKZO-TV. It immediately became apparent that the TV tower would also be suitable for an FM antenna at reduced power. On June 25, 1951, WJEF-FM took to the air waves with an effective radiated power of 115,000 watts. WJEF-FM operated from this site for ten years and, in 1961, WKZO-TV moved its transmitter to the new Gun Lake site, located half-way between Grand Rapids and Kalamazoo, Michigan. When the new TV transmitting equipment was placed into operation, it made equipment on hand, such as the "RCA 25AL TV amplifiers", available for the FM operation and to fulfill, after ten years, WJEF-FM's dream of serving the people of Western Michigan with a one-half-million watt signal.
During this entire period of time, the income of WJEF-FM was not great enough to pay the power bill, but, the Fetzer Broadcasting Company has always had great faith in the possibilities in FM and felt that it was in the interest of all of the radio public to keep this FM facility on the air for the public's enjoyment. In order to realize some income from the operation, the Fetzer Broadcasting Company purchased a Muzak franchise for Western Michigan and began the first multiplexed operation in this part of Michigan. The increase in power to one-half-million watts (ERP) produced even greater multiplex potentials which coincided with the initial decision to purchase the Muzak franchise. All this took place during the years that FM stations all over the country were going off-the-air because they felt FM could not exist with TV and AM. WJEF-FM radiates its signal to an area ninety miles in radius from the transmitter site. In addition to its metropolitan-area coverage, it covers a great rural area that would not, otherwise, receive service from a lower-powered transmitter.
WKZO-TV Moves to Gun Lake
During 1960, Fetzer management decided that it was time for a modernization program. This resulted in the conclusion that WKZO-TV should locate its transmitter and antenna at a point midway between Kalamazoo and Grand Rapids so as to serve both communities equally well. Since the planned antenna tower for the new site would be 1100 feet high, it would make an excellent location for WJEF-FM's antenna. To keep WKZO-TV's signal on the air during the move from Kalamazoo to Gun Lake, management purchased a new TV transmitter for the new site thereby releasing the two 25-kilowatt TV-power amplifiers at Kalamazoo. These were Type TT-25AL, amplifiers and, since they operated on Channel 3, it was a relatively simple task to raise their operating frequency from 61 and 66 megacycles to 93.7 mc...WJEF-FM's assigned frequency...to diplex the amplifiers and raise the 10-kw output of the new RCA Type BTF-10D driver transmitter to 50 kilowatts of FM power.
The Type TT-25AL amplifiers use the well-known cluster of seven Type 5762 triodes operating in parallel in a grounded-grid configuration. This cluster design, owing to the physics of VHF frequencies and the mechanics involved, lends itself excellently to frequency conversions. The RCA BTF-50B transmitter design utilizes two TT-25AL amplifiers diplexed and driven by the BTF-10D. The modification of our units, as made in the field by RCA engineers resulted in the first BTF-50B transmitter. The performance of the system has been very satisfactory.
Side-Mounted Antenna System
WJEF-FM uses a 12-section, gapped-ring antenna (BFA-12A) attached to one leg of the TV tower at the 800-foot level. Center-fed, this array provides a power gain of 12.5 and raises the 50-kw transmitter output to 500 kw ERP. With the antenna system mounted on one leg of the triangular cross-section tower, it provides substantially circular coverage over a 25,000 square-mile area. This includes Kalamazoo and Battle Creek on the South, Grand Rapids on the north and Lansing on the east, plus dozens of smaller municipalities at all points of the compass. For 90 miles in any direction, FM receivers can receive WJEF-FM.
Gun Lake Facility
The transmitters of both stations, TV and FM, are housed in a modern, well- engineered building of prestressed concrete, clad in aluminum and buff-colored brick. The 1100-foot antenna tower stands immediately outside the north wall to practically eliminate outdoor-horizontal runs of transmission lines to the antennas. Locating the tower so close to the building presents a falling-ice problem during the Michigan winter. However, this is overcome through a specially-designed roof on the structure that withstands the potential damage of the falling ice.
A novel arrangement in building design places all of the electronic gear of the transmitters on grade level with the power transformers and blower equipment arranged in a basement room. This set up makes the transmitter room extremely quiet since the hum of transformers and the sounds of moving air stay confined to the lower level. Further, this arrangement reduces, considerably, blower vibration in addition to increasing the accessibility to the equipment.
Massive Plenum Chamber
Each of the blowers operating in the basement performs without an individual air filter. Instead, all of the air in the room is filtered prior to its entry into the room. Outdoor air, entering the side of the building, is first filtered via spun-glass filters. This air then passes through electrostatic filters to axial fans, which "pressurize" the basement room and thus make it a massive plenum chamber. Since the blowers operate in a dust-free atmosphere, there is no need to provide each blower with an air-filtering device. The blowers, mounted on concrete piers, push the filtered air upwards through the basement ceiling and into the bases of the transmitter equipment. Ducting, at the top of the transmitter cabinets, is thermostatically controlled so that the warmed air from the equipment goes directly outdoors in summer or, indoors in winter to thus heat the transmitter room. This loop system, using entirely-outdoor air, reduces the BTU requirement of the air-conditioning equipment in summer and, delivers fresh, warmed air in winter. Another advantage in prefiltering the air before it enters the basement room is the elimination of a settled-dust problem in the basement as well as providing a dust-less atmosphere in the transmitter room. This of course, simplifies maintenance.
When the station went to the half-megawatt ERP, management decided that the station should be an entity in itself and, for that reason, should generate its own programming. The staff spent many months in surveying and devising the programming that is now a part of everyday operation. WJEF-FM programs its educational and informational shows throughout the day instead of the early hours of the morning. The surveys also pointed out that the listener desires large blocks of time set aside for each musical category. As a result, WJEF-FM maintains a considerable disc- and tape-recorded library which provides an excellent range of literature in each musical category.
Discs and tapes supply the high-fidelity program material. The discs are played on BQ-51 Turntables and tapes on RT-21 and RT-7 tape machines. The RT- 21 is a reel-to-reel tape transport while the RT-7 operates with endless-loop cartridges.
RT-21 Stereo Equipped
To play commercial stereo tapes, the RT-21 Tape Recorder is equipped with a four track playback head in addition to the separate erase, record and play heads for two-track stereo tapes. This is a special feature of the RT-21 in that it permits the machine to play virtually all quarter-inch-tape recordings; full-track, half-track-stereo and four-track stereo tapes.
BQ-51 Turntables Use Lightweight Tone Arm
In the center of a horseshoe arrangement is a BC-6B Audio Consolette while the turntables are at either elbow of the announcer. Each turntable contains its own preamp and attenuator pad. The knob for the pad is located conveniently next to the turntable controls. Each RCA Lightweight Tone Arm supports a stereo phono cartridge famous for its quality reproduction. For Cueing purposes, BA-8 Cue Amplifier with self-contained speaker is used.
Cartridge Tape Simplifies Cueing
The self-cueing feature of the RCA RT-7 Cartridge-Tape Machine serves ideally for spot announcements. This, of course, permits greater use of the turntables for programs material. The cartridge-tape facility, being monophonic only, serves only in non-stereo announcements; the stereo commercials being played on the RT-21 or either of the two turntables.
Muzak Programming on Long-Play Tape
The SCA subchannel programming comes from two long-play tape machines located in the main control center adjacent to Studio 1. These two machines operate almost completely unattended in that the tapes come from Muzak pre-programmed for such operation. The signal from these machines travels via multiplexed microwave to the transmitter site. Here it modulates a 67-kc sub-carrier of a Type BTX-1A Multiplex Generator which, in turn, modulates the BTE-10B Exciter in the FM transmitter.
FM Stereo Programming
A portion of each day's programming is transmitted in multiplex stereo (FM Stereo) using an RCA BTS-1A Stereo Subcarrier Generator mounted at the top portion of the center cabinet in the BTF-10D FM transmitter. Since introducing stereo programming, WJEF-FM has built up a separate stereo record library.
The primary signal-coverage area serves more than a million families. More than 50 per cent of these families have indicated, via mail, that WJEF-FM was the first FM station they had ever heard. In many cases, the primary reason for buying an FM receiver was word-of-mouth praise for WJEF-FM programming by a neighbor or a friend. It's important to note that most of these new listeners are located in rural areas and, quite possibly, would have no FM service were it not for the half megawatt signal of WJEF-FM.
Fulfils A Dream
Fetzer Broadcasting management believes that high power and high fidelity go hand in hand. The two converted RCA TV amplifiers provide 50 kilowatts of transmitter power for WJEF-FM. The combination of this transmitter power and the new BFA-12A Antenna produces 500 kilowatts (ERP) of power. The availability of this equipment made it possible to fulfil a dream of serving the people of western Michigan with a one-half-million-watt signal.
More on WJEF-FM: Xen Scott of ABC News transcribed the following from the FCC microfiche files, August 22, 1994