Jim Hawkins WCBS WFAN Transmitter Tour

High Island showing bridge from City Island

Official web pages



Location Marker

Accessed times since January 24, 2003

Click on thumbnails to obtain enlarged images.


Thanks to Scott Fybush and Garrett Wollman for inviting and driving me on this trip on 1/15/2003.
Thanks to Mike Erickson, WFAN Staff Engineer, for arranging the tour for us; Dick James, WFAN Engineering Maintenance Supervisor; Dan Lohse, WCBS Engineering Supervisor; and Mark S. Olkowski, Engineering Manager of WINS/WCBS/WFAN/WNEW, for the tour.
Scott Fybush writes Northeast Radio Watch and writes for Radio World and other industry magazines. His web site can be found at
fybush.com. Garrett Wollman works for M.I.T. and maintains the Boston Radio Archives at www.bostonradio.org.

Some Background

Both WCBS and WFAN are owned by Infinity Broadcasting Corp. WNBC, starting out as WEAF, was renamed WNBC (1946), then WRCA (1954), then back to WNBC (1960). WEAF moved to Bellmore on the south shore of L.I. before moving to Port Washington on the north shore. The call letters were changed from WEAF to WNBC in 1946, which later moved from Port Washington (Sands Point), L.I. to High Island in 1963. WNBC radio vacated the 660 frequency in 1988. WFAN, which was on 1050 at the time, took over that spot.

WABC/WCBS moved from Wayne, NJ to Columbia island in 1940, then joined WNBC on High Island in 1963, which is now accessed by a fairly new single lane bridge from City Island. The top photo was taken from the City Island end of the bridge. The history of the stations and transmission locations go farther back.

The island, also owned by Infinity, was once a resort with small log cabins. The main office or log cabin is still there and is the residence of the island care-taker and family as shown in a photo below.

For more complete historical backgrounds with more dates and details, please visit the links listed below.

Transmitter Building

The transmitter building is divided into two sides for WCBS and WNBC. Each side is separated by a (sort of) breezeway. One must go outdoors to pass from one station to the other.

WCBS 880 Side

Harris DX-50 Main
50KW solid state

Harris DX-10
second aux.
moved from the
WABC site.

Continental 317C-1
50KW tube aux.
Uses Doherty type

Phase rotator and
matching unit with
impedance measurement

Auxiliary Equipment racks.
Audio processing, etc.

WCBS on Columbia Island

WCBS Transmitter at Columbia Island

Photo Supplied by Rick Sedlak
Johnson City NY

WCBS Tower with Capacity Hat
on Columbia Island

From "The Modern Wonder Book of Knowledge" 1949
Columbia Island was surrounded by a 10 foot sea wall. The tower legs go through the building, but never "touch" it. They were buffered by insulating grommets. The nautical looking poles at the island corners were designed to serve as a back up antenna in the event of a loss of tower.

The transmitter was built by Federal Telephone of Newark, NJ.

--Pete Tauriello, 1010 WINS Morning Traffic Anchor

WFAN 660 Side

Continental 317C-1 and DX-50 in rear. There is an unseen
5 KW Gates transmitter at the end of the equipment racks
on the right side. My understanding is that this was, but is no
longer used as an auxiliary transmitter.

Phase rotator and matching unit with impedance measurement
bridge. This unit is used to match the phase of the outputs of
the DX-50, DX-10, and C317 transmitters to the impedance
looking into the transmission line. R+jX impedance matching
is done to keep sidebands balanced. I was told that this is
an uncommon practice at omnidirectional sites.

Some Historic Pictures of WEAF

before it became WNBC, WRCA, WNBC then WFAN

Bellmore, L.I. (South Shore)

WEAF 50KW transmitter in Bellmore, Long Island, NY
View of 32 water-cooled tubes. Water circulates through
coils of rubber hose at the base of each tube.

Photo: "Radio Telegraphy and Telephony"
Duncan and Drew 1929 pp 634. Click for enlargement.
RF Power amplifier and high power tuning system of WEAF's
50KW transmitter at Bellmore.

Photo: "Radio Telegraphy and Telephony"
Duncan and Drew 1929 pp 632. Click for enlargement.

Thanks to Bob Kozlerek WA2SQQ for enhancing these photos.
A Later view of WEAF
On left is the crystal controlled exciters.

Photo: Nationa Broadcasting Company
"The Radio Amateur's Handbook" Collins 7th Ed. 1933
WEAF transmitter at Bellmore, upgraded to RCA 50B

Photo: "Radio News January" 1932

WEAF TOWER, Bellmore

Source: Radio News January 1932

Port Washington, L.I. (North Shore)

WEAF Port Washington Transmitter building 1941 showing
water basin in front, used to cool the tubes.
Two quarter wavelength antennas are in the background.

Photo supplied by John Schneider - "
Voices Out of the Fog."
The interior transmitter toom.

Photo from Jan 1941 issue of "Radio & Television" magazine.

Tuning House

Tuning House


Austin Transformers

The tuning house contains a diplexer, which combines the signals of WCBS and WFAN, before applying them both to the antenna. The diplexer/combiner is basically two bandpass filters with outputs tied together to feed the antenna. The band of frequencies contained in the modulated signal in each case is passed through the filter to the antenna, but blocked by the other filter so that energy is not passed to the other transmitter. Impedance matching circuits are placed at the input of each side to match the transmitter to the input of the diplexer. The tower, ultimately is handling 100 KW of combined power
when unmodulated.

The Austin transformers couple the 110 V source to the 110 V line on the tower to light the tower lights, while isolating the RF high voltage of the tower. The interlocking rings are the primary and secondary of the transformer with a gap wide enough for the isolation.
Click button to hear sound of WCBS and WFAN in tuning house coils.

Diplexers/Combiners Made Simple

by Jim Hawkins

VERY simple example of a diplexer circuit.

The above schematic is an example of how reactive components can be arranged to combine the input signals to the antenna, while blocking signals to opposite transmitters. In the top network C1 and L1 are tuned to antiresonance to reject 880 KHz, while C2 and L1 are tuned to pass 660 KHz in series resonance. In the bottom network, L2 and C3 are tuned to antiresonance, blocking 660 KHz, while C3 and L3 are tuned to series resonance, passing 880 KHz. In the real world, additional components are used to shape the bandwidth and implement more complete attenuation to the opposite input.

Note, that a cross-over network for a high fidelity combination of speakers for an audio system is also a diplexer, except that it works in reverse. Energy is applied to the common node and the networks split (rather than combine) the frequency bandpass for the speakers that handle those ranges. Thus, the diplexer is said to be bilateral.

Combiners are less common in the AM broadcast band than they are in television and microwave applications. Combiners are used, for example, on the Empire State Building to combine the signals of many FM and Television stations onto shared antenna arrays.

Antenna Towers

Head's up view from the base of the
528' main tower. The tower is top
loaded and the guys to the first
insulator before the top, capacity hat
section of the guy are Phillystran
fiber rope.

View of end, which used to be
a separate insulated section, but
is now attached to the lower
part of the tower.

The RF is series fed to the tower
base through looped tubing,
which helps to block lightning strike
current. In conjunction with the
spark gap, lightning is diverted to
ground. The metal extensions on
each corner enable jacking up the
tower to replace the base insulator.

Guy Insulators

Auxiliary tower

Dick James next to guy insulator
assembly to show its relative

One of the guy wire anchors.

R.I.P. Pieces of mutilated antenna
resulting from airplane collision in


Inward Blowers for the WFAN Continental
317C-1 plate transformer, which is behind
the wall.

The WCBS 317C-1 is cooled using a closed
loop air system.

The Island Care Taker lives in this
Log Cabin at the southeast end
of High Island.

Transmission for WFAN and WCBS lines in center
section of the transmitter building. A third is a
pressurized spare. The lines run out of the top of
the phase rotator units, then down the center to run
underground to the antenna.


by Jim Hawkins - WA2WHV


Amplitude modulation is a process which uses the audio signal to modulate or vary the actual power of the radio frequency signal called the carrier. When no modulation is applied, a steady radio frequency signal is transmitted, creating a "quiet" spot on your radio dial. When analyzed, the AM signal is quite complex. It can be shown to be made up of 3 basic components: a steady carrier, an upper sideband signal and a lower sideband signal, which I will not explain here. AM is susceptible to static interference from lightning, motors, light dimmers, fluorescent lights, etc. When I am listening to an AM program at home and hear a steady, static "buzz", I find that it is usually one of the light dimmers in one of the bathrooms. I also remember the buzz of the electric shavers on an AM station playing while sitting in the barber's chair and hearing a POP when the shaver was turned on or off. These sources of interference are, themselves, forms of AM signals, which is why they easily infect your listening pleasure on AM with undesirable sounds.

In contrast, FM (Frequency Modulation), discovered by Edwin Armstrong, is a method where the carrier frequency is varied or modulated rather than the amplitude of the carrier. It is almost free of the aforementioned types of interference and is now the most popular means of broadcasting music programming. AM remains the choice for "TALK/NEWS" radio formats. AM broadcasting signals also have a longer range than FM, which is more because of the frequency at which they are transmitted than the method of modulation.


Digital Amplitude Modulation was invented by Harris Senior Scientist Hilmer I. Swanson. In older vacuum tube AM broadcast transmitters, the carrier was modulated by using an analog modulator, which was essentially the output of a powerful audio amplifier superimposed on the supply voltage to the transmitter. For reasons I won't explain here, this type of modulation required an audio signal which was 1/2 the power of the transmitter. That is, for a 50,000 watt transmitter, you needed a 25,000 watt audio amplifier! That is a slightly simplified explanation, but it suffices for this comparison. These modulators also required large modulation transformers to couple the modulation output tubes to the power supply system.

In the Harris solid state digital transmitters, the audio signal enters the transmitter through an A/D converter, which converts the signal to a digital audio form, much like you would find on a CD or a "WAV" file on your computer. The digital audio is a stream of binary numbers, which represent the amplitude of points sampled at particular time intervals along the audio input signal.

The digital audio output of the A/D converter is fed to the "integrator" board, containing logic which uses the digital input information to turn on (and off) the appropriate RF modules. There are four module step sizes: 100 Watt, 300 Watt, 500 Watt and 1000 Watt. The integrator module logic figures out which modules to switch on or off during the course of modulation. For example, as the audio waveform value goes up, a 100 watt module turns on. Then it is turned off and replaced by a 300 watt module, then a 500 watt module, then finally a 1000 watt module. As the audio waveform value continues on the upward slope, the 100 watt module turns back on, but this time, leaving the 1000 watt module turned on. Then the low power switching sequence continues as before, but this time, adding to the first 1000 watt module. As the audio signal value continues to climb, 1000 watt modules are added together and the smaller modules are swapped to handle the smaller steps. So, the output power step sequence might be 100, 300, 500, 1000, 1100, 1300, 1500, 2000, 2100, 2300, 2500, 3000 and so on, until it reaches the positive peak of the modulation signal. The same thing happens as the audio values swing toward the negative peak, but this time, the small module steps are swapped to smaller steps, and the 1000 watt modules are continually shut off as the modulation signal moves toward the negative peak. The lowest possible output is 100 watts, where only one 100 watt module is turned on. This occurs only at maximum modulation percentages. This is a form of pulse modulation, but is not like the Pulse-Step modulation used in ASEA BROWN BOVERI shortwave transmitters, which employ a combination of this additive stepping and pulse width modulation. As an additional bonus, if half of an output module fails, the integrator detects it and switches to a working module. So, a single module failure results in no reduction of power. In fact, ten modules could fail without it being noticed until the engineer actually goes to the transmitter and notices the failure lights turned on.

The multi-ton, multi-KW modulator is thus replaced by a few small printed circuit boards!

There are other types of digital modulation such as PWM (pulse width modulation) and PPM (pulse position modulation), which I will not discuss here.


Each output module is fed with a square wave from the driver section and outputs a square wave. The square wave output from each module is fed through a coil wrapped around a toroid. A pipe runs through the center of all the toroids, acting as a secondary transformer winding for all the toroids, which picks up the combined output of all energized toroids. The toroid filters most of the square wave harmonic components out, leaving an almost pure sine wave which represents the radio signal. There are other filtering networks before it gets to the output network in the transmitter, so by the time it gets to the output, the signal is a pure sine wave.

You can think of the modules as pistons in an engine, each putting out bursts of power, and the toroid coil as a flywheel which smooths the oscillation. In fact, if just one burst of power were applied to the toroid, it would continue to "ring" momentarily just as a fly wheel would continue to spin if you gave it one push. Without continued pulses of energy, the energy would eventually spin down due to losses. In the case of a flywheel, the losses are due to friction. In case of the toroid, the losses are due to resistance in the conductors. A toroid transformer is a donut shaped piece of iron, with coils of wire wrapped around it.

When there is no modulation (silence), 48 modules will be turned on simultaneously to generate approximately 55 KW (5 KW is lost on the way to the antenna). To modulate the transmitter, modules are turned on and off. As you turn more modules on, you have more RF carrier and when you turn more off, you have less RF carrier.

The digital technique used in these transmitters is extremely efficient (90%) as opposed to about 64% with the old high level plate modulated vacuum tube transmitters. That is, the older transmitters might use 78,000 watts to obtain a 50,000 watt output signal where the modern, solid state transmitters might use 55,000 watts to obtain a 50,000 watt output signal. That's a 23,000 watt savings (not to mention the absence of a 25,000 watt modulator) and quite a difference in the electric bill! The voltage applied to the output units is 240V and current runs about 300 AMPS. The power supply is fully contained within the cabinet and basically consists of a transformer which steps 440 VAC down to 240 VAC with some big diodes for rectification.

From power line to output, the efficiency is approximately 78% for these transmitters.


If you could stop the modules from putting out a squarewave at the carrier firequency and set the outputs to a steady DC voltage, the DX-50 would simply be a high powered D/A converter/power amplifier, one that converted low power digital, to high powered analog output!


In the older transmitter, huge blowers were used to cool the tubes. The air heated by the tubes was typically around 130 degrees F. With the new transmitters, relatively small air conditioners are used for cooling. Upon putting my hand in front of the output air vent, the air was barely warm.

See the Harris DX SERIES page for more information.

This is one of the output modules containing 8 output transistors. The module is capable of delivering approximately 1.5 KW output. The input and output is a squarewave whose fundamental frequency is that of transmitter's radio frequency. In the case of WCBS or WFAN, it is 880KHz or 660KHz. Note the Quarter next to the unit for size comparison. Each has a pair of green lights to show the modulation occurring and a red trouble indication light.

More on High Island

In 1913 Nora and Jack Beatty lived on High Island in a two-story, wooden farmhouse, renting out campsites. In 1925, the Miller family purchased the island and built 20 bungalows there, providing a summer resort for about 100 people. Before a footbridge was constructed to connect it to City Island in 1928, residents accessed the island by walking on a sandbar at low tide or took a boat at high tide. Residents began to park their cars on City Island, transporting furniture, groceries and other necessities to the island by wagon.

About eight of the families who leased bungalows became attached to the island and decided to make it a permanent home. In 1960 they unsuccessfully fought a zoning change that enabled WCBS and WNBC ultimately to buy the island for their transmitter facilities. A few years later, the bungalows were razed, the trees were cleared, the bridge was widened, and the transmitter facility was built.

A remaining log cabin is the last vestige of the old community, which is now owned by a care-taker paid by WCBS and WFAN to maintain the island.

The island is regrown with a variety of trees and brush and shores of the island are rocky.

Reference: "The Other Islands of New York City - A Historical Companion" by Sharon Seitz & Stuart Miller,
© 1996

© Copyright MMIII James P. Hawkins