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October 30, 1931…NBC Begins Work On Empire State Tower

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Eyes Of A Generation.com

October 30, 1931…NBC Begins Work On Empire State Tower

On this day in 1931, NBC began putting a TV transmitter and antenna on top of the Empire State Building. The first experimental TV broadcast from the building was on December 22, 1931.

As you can see in these photos, which were all taken before 1935, there was no tall mast on the building at the time…just kind of a rounded dome. The RCA tower was built on top of that.

RCA’s first experimental television transmissions began in 1928 on station W2XBS located near the Van Cortlandt Park area in the Bronx. Within a year it was moved to the New Amsterdam Theater Building, transmitting 60 line pictures in the new 2-3 mHz band allocated to television.

A 13 inch Felix the Cat figure made of paper mache was placed on a record player turntable and was broadcast using a mechanical scanning disk to a scanning disk receiver. The image received was only 2 inches tall, and the broadcasts lasted about 2 hours per day. By 1930 the station became part of NBC and began to transmit from NBC’s new home at 711 5th Avenue.

The Empire State Building was completed in May of 1931, and RCA leased the 85th floor for a studio and transmitter location for experimental television broadcasts. RCA, through its broadcasting division NBC, applied to the Federal Radio Commission on July 1, 1931 for construction permits for the sight and sound channels of a television station, which were issued on July 24, 1931.

The call sign W2XF was issued in December 1931 for the “sight” channel of that station on an assigned frequency of 44Mc. The RCA transmitter had an input power to the final stage of about 5Kw, giving an estimated power output to the antenna of about 2Kw.

The sound channel of the TV station was separately licensed as W2XK for a 2.5Kw transmitter to operate on 61Mc. Both transmitters were located on the 85th floor and used separate vertical dipole antennas.

In 1936, the tall tower like structure was added as a mooring mast for blimps. The winds proved to be too strong and there were several near accidents in mooring tests, but it did make for a great new antenna mount. -Bobby Ellerbee




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7 responses to “October 30, 1931…NBC Begins Work On Empire State Tower”

  1. Dennis Degan

    The top antenna is basically a ‘dual ring dipole’. That’s two dipoles shaped into the two halves of a ring (duh!). Further explanation: A dipole is a single wire folded into a loop in the shape of a ‘T’ (It has two ‘poles’, therefore it’s called a ‘dipole’). If it is a flat dipole, the RF pattern created is a figure ‘8’, with a strong field on both flat sides of the ‘T’ and very little RF at each end of the length of the ‘T”s horizontal top part. If you take two flat ‘T’s and curve them horizontally to form 180 degrees of a circle, and put the two together to form a whole ring, you’d have what’s shown in the photo. Note that the two halves do not touch. The RF pattern that is formed by this antenna radiates horizontally outward in all directions. But this simple ‘1-ring’ design has very little gain because much of the RF is lost to the sky and ground. To alleviate that, multiple rings can be stacked vertically to ‘squash’ the RF down, making the horizontal beam stronger than the vertical one. This is called a ‘stacked array’ (also, duh!).

  2. Jim Palmer

    The concept of a safety harness was a lot different back then.

  3. David Breneman

    What a shame to turn away all that lucrative dirigible traffic.

  4. Neil Borrell

    Neil Borrell I was a Master Control engineer at WOR-TV in 1967 when Master Control was in the Empire State building and I got to stand up there one beautifully clear and scarily windy afternoon. It was amazing. I never let go of the handrail.

  5. Bob Makson

    Notice the safety gear…the guy with the tie!

  6. Peter Sullivan

    Nice! Bobby… many of us in transmission still think the gorilla is still in that room!

  7. Albert J. McGilvray

    Any known address for the Van Cortlandt Park facility?

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