From the November 1962 issue of RCA Broadcast News, Vol. No. 115.
WJEF-FM . . . STEREO AND SCA WITH
HALF-MILLION-WATTS ERP
Grand Rapids Station Uses RCA 50-Kw Transmitter and
12 Bay Antenna for 25,000 Square Mile Coverage
by 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 t 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.
Amplifier Conversion
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.
Building Features
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.
WJEF-FM Programming
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.
Program Sources
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 (see Fig. 9).
Audience Response
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.
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