By John Schneider, W9FGH


Copyright 2015 -
John F. Schneider & Associates, LLC

 [Return to Home Page]

(Click on photos to enlarge)

WJZ Scientific American
A studio view, showing the beginnings of WJZ at the Westinghouse factory in Newark (Scientific American, 1922)

WJZ Scientific American 1922
A  view of the WJZ transmitter plant  at the Westinghouse factory in Newark (Scientific American, 1922)

WJZ Newark 1923

Musicians perform in the studio of WJZ in Newark, 1923.  A candlestick microphone and a large suspended cone-shaped microphone can be seen, along with a horn speaker.  Early radio studios were typically lined with heavy draperies to deaden the acoustics.  (Author’s collection)

WJZ Newark, 1923
This view of the WJZ operating room from 1923 shows a newer, 500 watt transmitter.  The cabinet at left contains six rectifier tubes that supply the plate voltage for the transmitter, at right, which has five modulator and four oscillator tubes.  The engineer in the center is checking the transmitter’s frequency with a wave meter.  

WJZ studio, Aeolian Hall
WJZ studio at Aeolian Hall in New York, about 1924.    (Colorized by author)

WJZ studio, Aeolian Hall
Another view of the WJZ studio at Aeolian Hall in New York, about 1924.

WJZ and WJY transmitters, 1923
This was the operating room of WJY and WJZ in the Aeolian Hall Building, 1923. The transmitters can be seen in line behind the operator’s desk. 

Edwin Armstrong on WJZ tower
This famous photo shows inventor Edwin Armstrong performing acrobatics on one of the WJZ towers on the roof of the Aeolian Hall, 400 feet above street level, on the day of the station’s official opening in May, 1923.  Armstrong reportedly did it to impress RCA president David Sarnoff’s secretary, who later became his wife.  Sarnoff was not amused, and declared the roof to be permanently “off limits” to Armstrong.

WJZ Bound Brook building
This is an outside of view of the WJZ transmitter house and antenna at Bound Brook, 1926.  The 455 meter antenna downlead and tuning house can be seen at the left.  The 100 meter antenna is on a pole to the right of the building.  The second tower is out of view at the left of the photo.  (Author’s collection)

WJZ shortwave antenna
This view of the WJZ transmitter building shows the 100 meter shortwave antenna.  The water cooling tower is in the background at right.  (Author’s collection)

Antenna Tuning House
This was the antenna tuning house, located directly underneath the antenna.  (Author’s collection)

Antenna tuning house
Interior view of antenna tuning house, showing the tuning network with its motorized adjustable capacitor plates.  The wooden box at the top contains a 30 ampere antenna current meter.  (Author’s collection)

Bound Brook transmitter room
This was the main operating room of WJZ at Bound Brook, New Jersey, 1926.  Shown are the two 455 meter Westinghouse oscillator panels against the back wall, and one modulator panel and two rectifier panels along the right wall.  The operator’s desk with its radio receiver and horn speaker is in the center.   The coiled tubing that carried the cooling water to the rectifier tubes can be seen in the far right cabinet.  The glass feed-through window on the back wall was where the transmitter power exited the building and went to the tuning house.  (Author’s collection, colorized by author)

WJZ oscillator cabinet
This is a view of one of the two 455 meter oscillator cabinets.   The coiled water tubing and six oscillator tubes with their water jackets attached were clearly visible to the operator.  In fact, everything was exposed and only an iron railing protected the operator from accidental contact with lethal voltages. (Author’s collection)

WJZ shortwave transmitter
This was the 100 meter shortwave transmitter, which sat on the opposite end of the room from the medium wave equipment.  The three panels, left to right, are the rectifier, modulator and oscillator.  (Author’s collection)

Modulator cabinet rear view

A WJZ engineer shows a rear view of one of the modulator cabinets.  The lineup of power tubes with their water jackets attached can be seen at the top center of the cabinet.  (Author’s collection)

Power control cabinet
This was the main power control panel for all equipment at WJZ.  (Author’s collection)

Motor generators
These two motor generators in the basement provided the 15 volt DC current for all the tube filaments.  The switching equipment for the 4,400 volt three phase incoming power can be seen in the background.  Filter capacitors for the plate voltage are at the right.  (Author’s collection)

Operator's desk
This was the main operator’s position for WJZ in Bound Brook.  The operator was responsible for maintaining the station on frequency and keeping the program log and meter readings.  The cabinets at right contain audio amplifiers for the incoming program lines. (Author’s collection)



WJZ debuted on October 1, 1921, founded by Westinghouse Electric.  Originally, the station was located in a shack, accessible only by ladder, on the roof of a Westinghouse factory located at Orange and Plane Streets in Newark, New Jersey.  This was Westinghouse’s radio station – preceded by KDKA in Pittsburgh and WBZ in Springfield, Massachusetts.   The 500-watt WJZ transmitter was an exact duplicate of the one built for KDKA.  Before long, a more comfortable two-room studio suite was opened inside the factory walls.

 WJZ initially shared its 360 meter (833 kHz) frequency with several other New York area stations until it was able to move to its own 455 meter (660 kHz) channel in 1923.  In May of that year, RCA acquired the station from Westinghouse, and WJZ moved from the Newark factory to the Aeolian Hall at 29 West 42nd St in New York, where it shared studio and transmitter facilities with a sister station, WJY.  Each station had its own finely-decorated studio on the sixth floor, and there was also a large glass-enclosed studio at street level that could be used by either station.  The two stations shared a single antenna suspended from a pair of hundred-foot towers on the roof of the building.  RCA’s opulent new broadcast complex was dubbed “Radio Central”.   In 1926, RCA purchased AT&T’s showplace station WEAF for $1 million, and its studios were moved over to Radio Central.  (WJY, the runt of the litter, quietly disappeared from the air).  The purchase agreement included guaranteed access to AT&T long lines, and RCA immediately established a network of several stations in the Northeast, which it called the “WJZ Chain”.  WEAF also had its own chain of stations.  Later in 1926, after RCA inaugurated the National Broadcasting Company, this chain was expanded to become the NBC Blue Network, and the WEAF chain became the Red Network.  By that time, WJZ was operating with 1,000 watts and WEAF with 5,000 watts.


Up through mid-twenties, radio stations were still broadcasting with relatively low power, and atmospheric noise and signal fading were significant impediments to listener satisfaction, especially during the summer months.  In 1925, five kilowatts was still considered to be high power, and most stations were still operating with 1,000 watts or less.  To overcome the reception issues, a group of major broadcasters pressured Secretary Herbert Hoover at the Department of Commerce to authorize higher transmitter powers.    Hoover responding by permitting higher power on an experimental basis for a few stations – principally those belonging to RCA’s “Radio Group”.  Westinghouse station KDKA was the first to be authorized, with 10 kW in 1924, later increasing to 40 kW.  In August, 1925, General Electric’s WGY was permitted an experimental 50 kW, becoming the first station in the country to operate at that power.   In December, Hoover approved WJZ as the country’s second 50 kW station – a fifty-fold increase from its Aeolian Hall transmitter power.  WEAF was to be the fourth super-power station, and it would follow WJZ on the air in October, 1927.

 Due to concerns that such a powerful signal would overload the vast concentration of consumer radios in the New York metropolitan area, a rural antenna location was needed.  RCA engineers scoured the countryside within a 50 mile radius of New York, and finally chose a 54 acre site at One River Road near the town of Bound Brook, New Jersey -- population 6,000 -- 35 miles West of New York.  The location was determined to have “excellent atmospheric qualifications for broadcasting”.


 RCA’s two major manufacturing partners were awarded the contracts to build the transmitters for WJZ and WEAF.  Westinghouse would build the WJZ transmitters, while General Electric took on the WEAF project.  The two companies chose substantially different topologies, with the Westinghouse design suffering from a number of technological limitations.  It was simply a brute-force implementation of the standard transmitters of the time -- essentially a free-running modulated high-power oscillator (“self-excited”).  This was before the invention of crystal frequency control, and so they required continuous monitoring and manual adjustment of the carrier frequency.  Meanwhile, radio technology was advancing so fast that the extra few months that G.E. had on the WEAF project resulted in a much more modern device.  It featured crystal control, and used the MOPA (Master Oscillator – Power Amplifier) configuration that would quickly become the standard for transmitter construction.  (See the December issue for a full description of this transmitter).  Nonetheless, all of the transmitters built on this contract would be obsolete and replaced in less than four years’ time. 

 The 30 x 70 foot two-story transmitter building that RCA built in Bound Brook was a virtual duplicate of the one that RCA was building for WEAF about the same time at Bellmore, Long Island.  The attractive colonial-style building was designed to blend in with the rural, residential environment.  However, inside it was strictly a serious commercial structure.  All of the power and mechanical equipment was located in the basement, with the transmitting and operating equipment being housed on the second floor.  External structures behind the transmitter house included a power substation, an antenna tuning network, and a heat exchanger for the recirculating water-system that cooled the transmitter tubes. 

 The 450 meter antenna was a conventional T-type design, supported by two 300 foot towers.  They were separated by 700 feet, although the horizontal antenna itself was only 220 feet long.  It consisted of a six-wire horizontal cage with a download wire in the center.  At both ends, the antenna halyards ran through pulleys atop the tower down to 2,000 lb. suspended concrete counter-weights which maintained the proper tension on the antenna.   The antenna was fed through a tuning network installed in a hut located directly under the antenna.  Motor-operated variable air capacitors were adjusted by remote control from inside the transmitter building.

 In addition to WJZ’s normal frequency of 455 meters (660 kHz), there was also a shortwave transmitter operating on 100 meters (2,998 kHz).  The antenna for this station consisted of a vertical copper pipe mounted on a wooden pole.  A loading coil with an antenna current meter were located in the center of the antenna.

 The local electric utility delivered 3 phase 4,400 volt power to the Bound Brook building.  In the basement, huge transformers converted this to 10,000 volts needed for the transmitter plate voltages.  This voltage was sent upstairs to the rectifier tubes, and then it returned to the basement where the filter capacitors and chokes were located.  Also in the basement, a duplicate pair of motor-generators provided 15 volts for the tube filaments.

 There were three transmitters on the main floor:   duplicate 450 meter transmitters and a 100 meter shortwave transmitter.  Each one consisted of three independent open-frame panels – the rectifier panel contained six rectifier tubes; the oscillator panel had eight tubes; and the modulator panel had twelve.  All of these tubes were cooled by a closed-circuit circulating water system that ran 3,300 gallons per minute of distilled water through an outdoor heat exchanger cooling tower.  Also on the main floor, a large seven-panel switchboard controlled the power for all equipment.  There was also an operator’s audio control panel in a separate room.


 On December 7, 1925, WJZ fired up the new Bound Brook transmitter for the first time, broadcasting with the experimental call sign 2XAR.   The response from Bound Brook residents was instantaneous -- they complained that the powerful new signal was blanketing out all other stations on their radios!  In just a few weeks, the Department of Commerce received 1,500 letters of complaint from unhappy listeners.  Herbert Hoover noted:  “This particular station (WJZ) has been broadcasting for some ten days using about forty kilowatts of power.  This is a very large amount, and the department has received a considerable amount of complaints from broadcast listeners in its immediate vicinity.“   Until the problem could be rectified, Hoover ordered WJZ’s power reduced to 5 kW.

 RCA sent out teams of engineers to visit homes in Central New Jersey to deal with the complaints, but this effort had limited results.  The principal cause of the problem was the lack of selectivity in the early TRF and regenerative radios that consumers owned.  They were designed to pick up the weak signals of the early and mid-twenties and were simply overwhelmed by such a strong local signal.  The more selective super-heterodyne receivers were just starting to come onto the market, but they were expensive and limited to a handful of models being made by RCA, who jealously controlled the patents on the technology.  Also, the AVC (automatic volume control) circuit had yet to be invented.  The final solution to WJZ’s problem would have to wait for the next generation of receivers to reach consumers’ hands.  In April of 1927, WJZ was permitted to increase its power to 45 kW, but after a barrage of new complaints over two months, it was ordered to cut back to 30 kW.  The station stayed at that power until the F.C.C. finally authorized 50 kW full time operations in 1935.  The Westinghouse transmitter was replaced with a more modern and stable RCA 50B in 1931, although it remained in place as a standby transmitter for a few more years.


 RCA engineers and the Department of Commerce analyzed the results of these first experiments in high power radio broadcasting.  They determined that high power produced louder signals and reduced atmospheric noise over a larger area, but that the gain was not proportional to the amount power increase.  Nonetheless, the 50 kW experiment had proven successful, and several dozen stations around the country – principally on clear channel frequencies – were on the air at that power level by the early thirties. Other methods to improve radio reception would soon be explored, including a conversion from the flat-top “T” antennas to vertical radiators above a ground system, which dramatically improved ground wave reception.  In 1936, WJZ would build a 640 foot anti-skywave tower at Bound Brook that would more than double its nighttime coverage.

 Another solution being considered to reception issues was a further increase in power – this time up to 500,000 watts.  In Cincinnati, Powel Crosley’s WLW was given the experimental authority to operate at that power.  For that project, Westinghouse, General Electric and Westinghouse all combined forces to build a monstrous two-story transmitter.  When it went on the air in 1934, its primary daytime coverage area encompassed six states, and at night it covered the entire eastern half of the country.  With this kind of coverage, WLW essentially became a one-station network, and Crosley was making money hand-over-fist in spite of the immense power bill. 

 Many other broadcasters observed the Cincinnati gold mine, and decided they wanted in on the action.  In short order, a number of stations around the country, including WJZ and WEAF, had also filed for super-power authority.  This created a political problem for the F.C.C., because the AM band was unable to support very many of these stations without sacrificing local service.  The battle eventually became politicized and it ended up in the halls of Congress, who in 1939 finally settled the matter by declaring a 50,000 watt ceiling for all broadcast stations in the United States.   WLW was ordered to reduce power to 50,000 watts on March 1, 1939.

 At one point in these negotiations when the outcome seemed more positive, RCA had been confident enough to build a 500 kW transmitter for WJZ, which became a white elephant after Congress’ decision.  RCA eventually sold it to the British Secret Service for £165,000.  It was shipped to the U.K., where it was placed in service during World War II as the famous black propaganda station Aspidistra.  


 WJZ saw a number of other changes and improvements over the succeeding years.  In November of 1928, it moved from 660 to 760 kHz, with sister station WEAF taking over the 660 frequency.  In 1941, it moved again to 770 kHz as part of the nationwide NARBA frequency shift

 In October of 1943, under an anti-monopoly court order, NBC sold the Blue Network, including its key station WJZ, to Edward J. Noble, and it became the American Broadcasting Company (ABC).  In January, 1944, the WJZ transmitter was relocated to a new tower on Route 17 near Lodi, New Jersey.  NBC continued to operate Bound Brook as a shortwave facility for its stations WNBX and WNBC until the end of World War II.  The site was then shut down, and today it is part of a housing tract.

 In 1953, WJZ’s call sign was changed to WABC, to reflect its role as the key station of the ABC network.  (This should not be confused with CBS’s New York station, which had been known as WABC for many years but became WCBS in 1946.)  WABC continues to operate today on 770 kHz with 50 kW from the Lodi site.  The WJZ call letters were brought out of retirement by Westinghouse in 1957, and continue to be heard today, on AM, FM and TV stations in Baltimore.




  • The Beginning of Broadcast Regulation in the Twentieth Century by Marvin R. Bensman
  • History of Radio to 1926 by Gleason Archer
  • “Scientific American” Magazine, March, 1922. “Radio For Everybody”
  • “The Electragist”, 1923, Vol. 22 No. 9, pg. 58
  • “Wireless Age” Magazine, July, 1923.  “Radio Broadcast Central” 
  • “Radio World” Magazine, Jan. 23, 1923 – page 16.  “Monster radio tower installed on roof of New York Skyscraper” by Robert L. Dougherty
  • “Radio News”, January, 1925
  • “Boys Life” Magazine, February 1926, page 26.  “Through Stations WJZ and WGY (sic)”
  • “Wireless World” Magazine, March 31, 1926, page 495.  “America’s New High Power Broadcasting Station” by A. Dinsdale.
  • “Radio News” Magazine, April 1926, pg. 1405.  “Views of the New Super-Power Station WJZ”. 
  • “Boys Life” Magazine, December 1927, page 68, “Sparks Visits WEAF’s New Home”
  • “WJZ and WJY, Fraternal Twins”, Arcane Radio Trivia,  http://tenwatts.blogspot.com/2013/12/wjy-and-wjz-fraternal-twins.html
  • "Tower site of the week” by Scott Fybush, May 27, 2005.   http://www.fybush.com/sites/2005/site-050527.html
  • Wikipedia articles about WABC, WJZ-TV, Aspidistra
  • An Aerial view of the WJZ tower site at Bound Brook can be viewed here:
    Library Company of Philadelphia, digital collections



NOTE:  This article appeared in the Spectrum Monitor Magazine, July, 2016.


John F. Schneider & Associates, LLC
Copyright, 2016