Tag Archives: United States Signal Corps

Alpine, New Jersey–My Recent Visit…


W2XMN–Armstrong’s original transmitter building built in 1937, 2010 November 6
W2XMN–Interior of building, 2010 November 6


I had the great pleasure of venturing out to Alpine, New Jersey this past Saturday. I was honored to receive an invitation from Dave Amundsen, the Director of Engineering for CSC Management (the organization who presently owns the Alpine site), to celebrate the 75th anniversary of Major Armstrong’s public demonstration of FM in 1935, through a live radio broadcast.

To be able to stand in close proximity to the original Armstrong tower was truly an incredible experience, and the engaging conversations with the many radio hams in attendance was priceless.

Steve Hemphill was kind enough to serve as a tour guide through the multitude of apparatus, including the one used to transmit the anniversary broadcast. Steve personally built a replica of Armstrong’s 42.8 Mhz FM transmitter, and has lent his helping hand to restore a variety of other instruments on the Alpine site.

The GE BT-1-B 250 watt FM broadcast transmitter that resembles an old refrigerator (photographs immediately below) is Steve’s handiwork. He purchased the GE 250 watt transmitter off Ebay back in August 2002 and refurbished it back to its original shiny and functioning glory.

GE 250 watt transmitter, 2010 November 6
Steve Hemphill with the GE 250 watt transmitter, 2010 November 6








I posted some photographs of the back interior of the GE transmitter to illuminate the amount of work involved in this project. You will see all new wiring–really quite incredible!

GE 250 watt transmitter–backside interior view, 2010 November 6
GE 250 watt transmitter–backside interior view, 2010 November 6










This particular GE transmitter originally belonged to WAVE-FM in the late 1940s and was subsequently sold to the Louisville Free Public Library for use as their transmitter at WFPL-FM, sometime in the 1950s. In 1950, public radio made its debut with WFPL when the Louisville Free Public Library became the first library in the country to obtain a radio license. They started broadcasting using a GE model BT-11-B transmitter (10 watt unit), later upgrading to the model seen here.

GE 250 watt transmitter–backside with "City of Louisville" tag, 2010 November 6


Armstrong’s tower stands as it did decades ago. The bottom of the tower has changed with the construction of a building that serves to house most of the apparatus.

Armstrong Tower, 2010 November 6
Armstrong Tower, 2010 November 6


Armstrong Tower, 2010 November 6







During World War II, Armstrong carried out contract work for the Signal Corps. The tower built for his work on radar still stands (photographs below), albeit with some modifications.

Radar Tower, 2010 November 6
Radar Tower, 2010 November 6







The W2XMN building contains a small museum housing various communications equipment. The photographs below are all from the museum.

Prototype of 30 KHz FM side-channel Multiplex Receiver, 2010 November 6
Prototype of 30KHz FM side-channel Multiplex Receiver, 2010 November 6






The 30 KHz FM side-channel multiplex receiver (photographs above), is a prototype of the receiver designed by John Bose in 1953. The receiver is described in detail in US Patent 2,835,803, issued to Bose in 1958 May 20.

Vacuum Tubes, 2010 November 6
Sample component wiring board–Part of Pulse Generator, Armstrong Experimental Radar, 2010 November 6



David Terwilliger–Radio Ham and textbook of knowledge, 2010 November 6


Double Super-het single knob, 2010 November 6















James O’Neal was kind enough to explain the meaning of Conelrad (CONtrol of ELectronic RADiation) to me. I have seen the CD triangle in a circle emblem on the back of radio apparatus and wondered what it signifies. Mr. O’Neal explained that during the Cold War Conelrad was set up to provide warnings to the public. The system was introduced in 1951, and if an alert was given, radio stations were to go off the air. Chosen stations were to move to either 640 or 1240 KHz, continually alternating so as to avoid enemy direction finding equipment capable of locking into US locations by using radio stations as beacons. In 1963, the Emergency Broadcast System (EMS) replaced Conelrad. Since 1997, the Emergency Alert System (EAS) has been used.

Also in attendance was John Nashmy, who in the aftermath of 9-11, assisted in moving a number of New York television stations to the Alpine site so they could continue broadcasting.



Death Ray?

D. Lippincott to Armstrong, 1942 March 13, page 1
D. Lippincott to Armstrong, 1942 March 13, page 2









No, Armstrong did not invent a death ray, but I did come upon an envelope with "Death Ray" written across the front in the collection. The materials contained within it are incomplete and as a result, there are a variety of holes to this tale. Reading through the documents, let me present a synopsis:

For some years prior to 1942, a Mr. Roberts, residing in New Castle, Delaware, had been trying to sell his death ray to the United States government. He refused to make a disclosure of said invention without a definitive commitment from the government to purchase it.

In 1942, the government engaged in a tentative contract with Roberts for full disclosure of the D.R. invention. The contract called for a disclosure to be made to a board, comprising three individuals. The three would consist of an engineer, a physicist and an Army officer.

Armstrong was contacted by the government through Major Donald Lippincott, who asked if he would be willing to sit on the Board. Armstrong had also been chosen specifically by Roberts attorney, George Finch, as the engineer to fill one of the three spots.  Finch acted as Roberts representative throughout the coming disclosures as Roberts was, at the time, incarcerated. He agreed to serve and signed non-disclosure documents which precluded him from discussing the death ray, at least for the next seventeen years.

Armstrong to Lippincott, 1942 March 21
Lippincott to Armstrong, request for non-disclosure, 1942 July 4

Witnesses were interviewed and gave accounts as to the utility and effectiveness of Roberts creation. The death ray was said to zap ducks out of midair, some thousands of feet high (allegedly, several ducks were retrieved from the road without so much as a mark to indicate cause of death), turn green grass into yellow ribbons, and slice trees horizontally, severing the top from the bottom half.

There are a few notarized witness accounts of the ducks mysterious demise amongst the materials. The following is from William B. Davis, Magistrate at New Castle:

When I saw the ducks and I had them in my possession for a day or two they were dead, their eyes were closed, they were wet, they had not been shot, they had no sign at all as to the cause of their deaths just seemed to be stunned to death.

Walter Borg statement relative to Roberts Death Ray, 1942 August 29, page 1
Walter Borg statement relative to Roberts Death Ray, 1942 August 29, page 2
Walter Borg statement relative to Roberts Death Ray, 1942 August 29, page 3
Walter Borg statement relative to Roberts Death Ray, 1942 August 29, page 4
Walter Borg statement relative toRoberts Death Ray, 1942 August 29, page 5

Walter Borg statement relative to Roberts Death Ray, 1942 August 29, page 6



Major Lippincott investigated the site himself. He visited New Castle to examine any evidence that may remain from supposed death ray invention. His account of the visit is seen in the documents below.

Lippincott memo regarding visit to New Castle, DE, 1942 August 29, page 1



Lippincott memo regarding visit to New Castle, DE, 1942 August 29, page 2













Lippincott memo regarding visit to New Castle, DE, 1942 August 29, page 3

















Lippincott memo regarding visit to New Castle, DE, 1942 August 29, page 4














At some point, either during the disclosure proceedings, or immediately following, Armstrong withdrew from the Board. I can not garner the reason why from the existing documents. Neither can I infer the final outcome or report that was eventually given by the Board. Judging from the last letter in 1943 from Major Lippincott to Armstrong (seen below), the final report was more than likely not in Roberts favor. But the question remains, did the United States government purchase Roberts claimed invention: the death ray?

Lippincott to Armstrong, 1943 February 23



Alpine, NJ–Modulator, Transmitter Mixer, Keyer A and Keyer B (left), Receiver (right), undated

When the second World War started in 1939, the United State Signal Corps approached Armstrong for assistance as they wished to use frequency modulation for mobile-military communications. Mobile FM was invaluable during the war and Armstrong allowed the US military use of his frequency modulation system royalty free for the entire war. No company offered such a generous deal and unfortunately, Armstrong’s income was diminishing rapidly and he needed funds to continue support of his Alpine and Columbia University laboratories.

Alpine, NJ–Antenna, close up, undated

Alpine, NJ–Antenna, undated

He accepted contracts to work for the military and began his experiments on radio detection and ranging systems. At the time, the radar employed was of the short wave type (pulse radar). Armstrong was in pursuit of continuous wave FM radar with the help of his chief technical assistants, John Bose and Robert Hull.

When the war ended in 1945, Armstrong had not concluded his radar work. Bose, Hull and Armstrong continued and eventually developed a working radar system. As opposed to pulse radar, the system they produced using continuous wave FM had a searching range far beyond the pulse method.

Alpine, NJ–Transmitter Building-North, Resnatron Cage (right), undated

In December of 1947, John H. Bose, Robert E. Hull and Edwin H. Armstrong filed United States Patent Application No. 794, 608 for Radio Detection and Ranging Systems.The first paragraph of the specification (found in the application) states:

"This invention relates to a new form of radio detection and ranging system for distant objects, commonly known as radar, which utilizes the principles of frequency modulation. It has for its object the provision of a more sensitive and selective system whereby greater sorts is obtained. It has also for its object the provision of means for distinguishing between fixed and moving target relative to the location of the radar station and the sense of motion."

Hull Radar Notes, pp 1, 1944 November 5

Hull Radar Notes, pp 2, 1944 November 5

Hull Radar Notes, pp 3, 1944 November 5

Hull Radar Notes, pp 4, 1944 November 5

Hull Radar Notes, pp 5, 1944 November 5

I have scanned some documents and photographs from Robert Hull’s logbooks (below) and notes (immediately above), which you see here. In addition, I have included the title page of one of the final reports (Contract W28-099-ac14) created at Alpine Laboratory for the US Military (immediately below), along with some photographs (top of post) found within that document. There are many more reports, notes and photographs regarding other US Military contracts held within the Edwin H. Armstrong Papers.

"High Power Frequency Modulation Doppler Radar System", Final Report, Title page, 1952

Logbook–Alpine Lab, Robert Hull, 1947 to 1949, cover

Logbook–Alpine Lab, Robert Hull, 1947 to 1949, index page

Logbook–Alpine Lab, Hull, pp 13, 1947 July 15

Logbook–Alpine Lab, Hull, pp 15, 1947 July 15

Logbook–Alpine Lab, Hull, pp 17, 1947 July 15

The Superheterodyne

When the United States entered World War I, Armstrong enlisted in the Signal Corps. In 1917 he was posted to France, placed in charge of the Radio Group of the Research Section of the Division of Research and Inspection. This Division had been created in order to examine any existing equipment manufactured by the Europeans for the American Expeditionary Forces.                                              

Round, Henry Joseph, 1960

The Major set off to France but en route he was delayed in England due to heavy fog. While there, he ventured to London, stopping by the Marconi offices. The letter seen here (below), dated 1917 October 28, from Armstrong to his mother, details his visit and recounts his introduction with Henry Joseph Round.

EHA letter to Mother, 1917 October 28, first 2 pages



EHA letter to Mother, 1917 October 28, last 2 pages



Round was an engineer with Marconi who, at the time, was in charge of the Admiralty’s wireless direction-finding stations. It was here that Armstrong was introduced to Round’s short-wave equipment. Round had created these amplifiers by designing his own vacuum tube (V24). These tubes were not, and would never be, available to the French and the Americans, as these tubes were not appropriate for the task. Armstrong’s attention was captured as this was a problem that required further research. 

 Armstrong had studied heterodyne circuitry for quite a while and understood it well. This meeting with Round pushed him further and he continued to examine the problem of receiving weak high frequency signals. As the Major recounts some years later upon receiving the Edison Medal in 1943:

"The third link came months later as I happened to be watching a night bombing raid and wondered at the ineffectiveness of the antiaircraft fire. I may say that night bombing was not very dangerous in those days, either for the man on the ground or the man in the airplane. Thinking of some way of improving the methods of locating the position of airplanes, I conceived the idea that perhaps very short waves sent out from them by the motor ignition systems might be used. The unique nature of the problem, involving the amplification of waves shorter than any ever contemplated and quite insoluble by any conventional means of reception, demanded a radical solution. All three links of the chain suddenly joined up and the superheterodyne method of amplification was practically forced into existence. Not one link in the chain could have been dispensed with. This, I think is the only completely synthetic invention I have ever made." 1

The bombing raid and third link, to which Armstrong refers above, occurred in Paris, March 1918. He had thus sorted out how to use the heterodyne principle to bring short-wave frequencies down to the range of his long-wave amplifier. He worked out the necessary experiments needed to prove his forthcoming invention, writing down the proposed method in June 1918 with Major Buckley signing off as witness (proposal seen here in 3 pages).

Method of Reception, Disclosed to Major O.E. Buckley, 1918 May-June, page 1


Method of Reception, Disclosed to Major O.E. Buckley, 1918 May-June, page 2










Method of Reception, Disclosed to Major O.E. Buckley, 1918 May-June, page 3

Following Armstrong’s proposed methodology to Major Buckley, experiments would need to be conducted. Armstrong needed assistance to stage these experiments and create the necessary apparatus. With war work taking precedence and his fellow officers tied up in other pressing projects, his work was delayed. The first model was not ready until November. Armstrong first applied for patent in France in December 1918 and for United States patent in February 1919.

When Armstrong returned from the war he presented his paper, "A New System of Short Wave Amplification," to the Institute of Radio Engineers in December of 1919, delineating his new receiver.

In 1920, Westinghouse purchased Armstrong’s regeneration and superheterodyne patents. Also, around this time, AT & T purchased Lucien Levy’s patent for essentially, the same invention. Originally Levy’s patent covered a different purpose than did Armstrong’s resulting in the US Patent Office not catching the conflict. Someone eventually noticed this apparent conflict and priority needed to be resolved.

The Court of Appeals in the District of Columbia ruled in Levy’s favor and his patent was issued on November 5, 1929, with a priority date of August 4, 1917 (he had filed 6 months prior to Armstrong). While Levy, by law, is considered the inventor of the superheterodyne method, Armstrong is recognized as bringing about its commercialization through the single tuning knob superhet receiver.



1-Armstrong, Edwin H. "Vagaries and Elusiveness of Invention," Electrical Engineering 62 (April 1943).

Additional Information regarding superheterodyne patent:

Schottky, Walter  "On the Origin of the Super-Heterodyne Method," Proceedings if the IRE, Vol. 14, No. 5, 695-698 (October 1926)

Armstrong, Edwin H. "A New System of Short Wave Amplification," Proceedings of the IRE, Vol. 9, No. 1, 3-27 (February 1921)

Douglas, Alan S. "Who Invented the Superheterodyne?," Proceedings of the Radio Club of America, Inc., Vol. 64, No. 3, 123-142 (November 1990)