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The Waldorf's 50-Foot All-Wave Receiver.
This is the radio room of the Waldorf-Astoria Hotel, New York City, showing the extensive array of equipment in the hotel's all-wave receiving and distributing system, where H.R. Martin, superintendent of communications, in the foreground, and two operators, H.D. Schwartz and J. Stevens, are shown tuning and routing programs.
|That international short-wave broadcast programs have a definite interest for the average listener is evidenced by the fact that one of America's largest hostelries has recently incorporated short-wave reception in its lobby and 2,000 guest rooms. A description of the great receiver, which undoubtably will be duplicated in other institutions, points out its many interesting features.||WORLD'S LARGEST ALL-WAVE SET
L.M. Cockaday, Radio News, August 1935
The thrills of all-wave listening are no longer a novelty. The great enjoyment of tuning-in the world in your own home is now a commonplace. So much so, as a matter of fact, that fans are bound to miss the universal program fare when away from home on business or pleasure trips. There is now an indication that leading hotels throughout the land, in cognizance of the allwave radio trend, may follow the suit of the famous Hotel Waldorf-Astoria, of New York, in converting centralized radio systems into allwave program relay plans.
What is claimed to be the world's largest allwave radio receiver has been installed in the Waldorf-Astoria by the Western Electric Company. The gigantic receiver supplants the centralized broadcast band unit previously used at the skyscraper hostelry. The new equipment makes available to 2,000 guest rooms, as well as lobbies, ballrooms and restaurants, the shortwave offerings of stations in England, France, Germany, Russia, Japan, Italy, Africa, South America--virtually all parts of the globe.
Previously, the Waldorf's radio system covered only the standard broadcast band of 550 to 1500 kilocycles. The new equipment adds the band of 2200 to 25,000 kilocycles. In addition to foreign presentations, such items as police, aviation, Government and amateur signals can be tuned in for the entertainment of the hotel's guests. It is the management's claim that it is the first hostelry in the United States to install such a system. The move was prompted by the international flavor of its clientele and its many foreign guests.
The radio receiving and amplifying panels of this huge receiver at the Waldorf are 50 feet long. The distributing network covers the entire structure. Up to the time of the addition of the shortwave apparatus, the hotel made available six programs composed chiefly of broadcast presentations, but also including electrical transcriptions and public events going on within the structure. Now the new equipment makes possible the inclusion of foreign programs. The day's programs of short-wave stations all over the world are examined by the hotel's radio staff and the most interesting items are selected and published in the hotel's house organ as the guests' tuning guide.
A novel antenna system, especially designed by the Bell Telephone Laboratories for the peculiar needs of the hotel has been installed. It is a predominantly horizontal aerial designed to combine efficiency and protection from interference. Three strands of wire were strung between the two towers, 660 feet above the street, in an unusual array. Two of the wires are crossed to form an X while the third resembles an inverted U. The lead-in wire is attached to the intersections of these strands and is stretched vertically down to the roof. Precise calculations in the arrangement and length of the wires are said to assure a constant selection of choice shortwave features.
THE ANTENNA SYSTEM
Each of the antenna wires is of different length to respond most powerfully to waves having related wavelengths. For example, one of the wires is 78 feet long, for 25 meters. This wire will respond with particular intensity to waves twice its length, or 50 meters. This is the wavelength of a transmitter on 6000 kilocycles. The same strand also responds to waves produced by odd multiples of this frequency, such as 18,000 kilocycles. A second wire responds to 12,000 kilocycles. The third responds to 3000, 9000, 15,000 and 21,000 kilocycles. This span of frequencies includes the bands which contain the world's most famous short-wave stations. The antennas also respond to adjacent bands.
It was pointed out that the new antenna eludes the vast amount of manmade static which, in such a metropolis as New York, arises from countless electrical sources. It was asserted that interference originating nearby presents a vertical front and the new type horizontal antenna is immune to them.
Interference had to be calculated with great care. The location of the Waldorf-Astoria Hotel seemingly presents many problems from this angle. On the Park Avenue side, the New York Central and New Haven Railroad trains pass by underground. On the Lexington Avenue side, there is a two-level subway and a surface car line. The side streets, Forty-Ninth and Fiftieth, have a bus-line going in either direction. All this, remember, is in addition to the vast amount of automobile traffic on all sides.
But modern equipment and engineering methods still succeed in routing world-wide short-wave programs to the hotel's guests.
The radio room is on the sixth floor of the structure. A special transmission line conveys the impulses down 600 feet without electrical loss and with complete protection from interference.
Short-wave receiving equipment utilized in the hotel is somewhat similar in design to the commercial apparatus at the International Bell System stations at Netcong, New Jersey, and Miami, Florida. Ship-to-shore telephone services also employ such types of apparatus. Thus, the hotel guests have the advantage of such a refinement as overcoming sudden fading by automatically increasing amplification to maintain a constant volume.
Outlets for the radio service in each room accommodate special receiving units with program selectors and volume controls. The units are rented to guests on a daily, weekly or monthly basis for a moderate fee.
A prominent feature of the Waldorf-Astoria receiving units is their high degree of selectivity. The circuits at one point are tuned by six condensers which function simultaneously worm gear reduction drive. There are eight additional fixed tuned selective circuits in the intermediate-frequency amplifier. It is such refinements in equipment that make practical the efficient sharp tuning required in the high-frequency bands where channels are so close to each other.
The short-wave set is contained in a cabinet about 7 feet high, containing a number of panels of sensitive equipment. The first units are three amplifiers covering, respectively: 2200 to 6000 kilocycles; 6000 to 13000 kilocycles,and 12,000 to 25,000 kilocycles. Five circuits tuned to the desired signal single it out and then it enters a vacuum tube which reduces it to a frequency of 385 kilocycles. The signal then passes to an intermediate-frequency amplifier where its energy is amplified about 100,000,000,000 times. A high-fidelity detector valve transforms this radio frequency into audio frequencies which cover the wide tonal range essential for faithful sound reproduction. Once again, the signals are amplified and pass into the hotel's 6-channel program-distribution system.
This elaborate all-wave system at the New York hostelry is a tribute, indeed, to the growth and popularity of short-wave DX program
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