Tag Archives: John H. Bose

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.

 

 

Radar…

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