Museum Hours:

Saturday 10-6

Sunday 12-5

Mechanical Television

Western Empire State Restoration

This is a console model lens disk receiver. It originally had two receivers; a AM one for the audio, and a shortwave one (2-3 mHz) for the video.

Cabinet.  The cabinet is in good condition. The plastic screen is badly deteriorated, and will have to be replaced.

Chassis. Here are pictures of the only other surviving Empire State. The set originally had two chassis. The upper one had a TRF receiver tuning 2-3 mHz and the circuitry to drive the neon crater lamp. The scanning disk assembly was mounted on this chassis. The lower one was a conventional AM receiver connected to an 8 inch speaker, for the audio portion of TV transmission, and also for radio reception.

Scanning Disk. This disk is from a Model 41, which was a table model set with a 4 inch screen. We will attempt to adapt it for the Empire State, which has a 6 inch screen. Only the motor, disk, and mounting brackets are original - the wood frame was built in the 80s.

Here is a description of the assembly from a Western engineer, William N. Parker, as told to Peter Yanczer in 1984:





Motor designed for 50 Hz operation

When we applied power to our motor and checked the speed of the disk, we discovered that it wasn't turning at 900 rpm. So we sent it to Peter Yanczer for repair. He took apart the gear assembly and discovered that the ratio was 2.22222 to 1, and that the motor turned at 2400 rpm. This resulted in a disk speed of 1080 rpm. At first Peter couldn't come up with an explanation, but then he remembered that Western exported a transmitter and some receivers to Mexico and Canada. Mexico used 50 Hz power, and Canada used 25 and 60 Hz. At 50 Hz the motor would turn at 2000 rpm, resulting in a 900 rpm disk speed with the 2.22222 to 1 gear ratio.

Here is a rough translation of a portion of a Mexican TV history web site:

1928 - 1930 PIONEERS:  The first experiments in television in Mexico were conducted by engineers Francisco Javier Stavoli and Miguel Fonseca, both professors at the Superior School of Mechanical Engineering and Electrica (ESIME) and of the Industrial Technical Institute.  Stavoli was, in addition, the technician in charge of radio station  XEFO of Partido Nacional Revolucionario (PNR), installed in 1930, which started broadcasting on January 1, 1931. This is why he was given the financial resources to travel to the United States to acquire a full complement of television equipment, including two mechanical cameras (using Nipkow disks), a transmitter and several receivers, as well as additional equipment to make experimental transmissions

1931 FIRST TRANSMISSION:  The equipment brought to Mexico by Stavoli was installed in  the building of the ESIME, located on Calle de Allende in downtown Mexico City. The transmitting antenna was placed on the church of San Lorenzo, situated on the corner of Calle de Allende and Belisario Dominguez.  After making some field tests, the initial transmission took place, televising the face of Mrs. Amelia Fonseca, the wife of Stavoli, the first image transmitted in Mexico by television.

Another quote from William Parker:


Scott Marshall sent this:

I was reading about your fascinating restoration of the Western Empire State and wanted to add a note about issue of 50 Hz and 60 Hz power systems. Los Angeles, and presumably other areas of California, had 50 Hz power in the 30's. I know about this because I restore vintage electric clocks. It was a big event when LA switched from 50 Hz to 60 Hz power. The Telechron company retrofitted all the city's clocks for free. Your 50 cycle Western set may actually be from LA and not Mexico.

According to the following web site, Los Angeles switched from 50 cycle to 60 cycle current when Boulder Dam went online in 1936:

50 Hz power was used in Los Angeles prior to 1936, and it is possible that our motor was designed to work there. Recently we got a 1936 brochure from National Schools in Los Angeles, showing Western equipment. So, our mechanism could have either been made for export to Mexico, or could have been made for use by National Schools.

Now we need to find a way to make it work on 60 Hz. There are two major ways we can do this. We can detach the disk from the present motor assembly and build a new one using a modern 900 rpm motor. This would mean that the scanning assembly wouldn't look anything like the original.

The other approach is to make a converter to produce 50 Hz locked to the video signal. This could be done in three ways: 1) modification of Darryl Hock's converter to output 50 Hz, 2) build a motor-alternator converter with a 60 Hz motor driving a 50 Hz alternator, or 3) build an electronic converter, perhaps with a 600 Hz phase lock loop locked to the power line, then divided by 12 to produce 50 Hz. The 50 Hz signal would then be amplified to drive the motor.

We experimented with operating the motor with 50 Hz using a 100 watt audio amplifier driving the motor. At 55 Hz, the motor would sync, but below that frequency it would not. The motor barely has the power to operate the disk, and at 50 Hz it is less efficient. When the motor and disk assembly was new, it worked on 50 Hz, but with ageing of the bearings and gears, it no longer works.

So, we have decided on a different approach. Darryl will modify his scan converter to output a triple interlace 18 fps signal, which will work with the 1080 rpm disk speed with the motor operating on 60 Hz.

We have built a chassis to mount the disk assembly on, and built a temporary driver for the neon, using a 6SN7 as amplifier and a 6L6 as the output tube. We have ordered high quality ground glass screen to replace the badly deteriorated one that came with the cabinet. I am visiting the Smithsonian soon to photograph and measure their Western Empire State, in the hope of replicating the scanner and receiver chassis.

The scan converter, with 18 fps video locked to the 60 Hz power line, arrived today. When we connected it to the scanner, we got a picture that locked perfectly on the screen. The image is quite dim and difficult to photograph, but relatively sharp. We have installed a new ground glass sheet to replace the badly degraded one that came with the set. 

After visiting the Smithsonian and inspecting their Empire State, I've determined that it is not practical to try to build a replica of the scanner chassis. The disk in the Empire is 11 inches in diameter (our disk is 9 inches), the lenses have a different focal length, and the mounting brackets are completely different. 

Instead, I'll put the drive circuitry on the chassis we have, using a 6L6 as the output tube, 5U4 as rectifier, and a 6SN7 as an amplifier. At some time in the future we may find the original chassis, or be able to build a replica which is more like the original. Here is the replica we have built. The 6L6 and 6SN7 are behind the disk. The controls on the L shaped bracket are on/off/gain (contrast) and neon current (brightness).

Crater lamps are high intensity neons with a very small spot size. The one used in the Empire State was made by the Garner Co., having a bayonette base and with the aperture on the side of the lamp. These lamps are almost impossible to find, but we finally obtained one. It has a heater element surrounding the crater chamber. Applying about 2 volts AC to this heater assures that the glow occurs within the chamber and not on the attached leads.

The original crater lamp was about the size of a large automobile tail light bulb, and has its aperture on the side. We built a replica of the mounting bracket to accommodate the lamp.