Western Electric No. 317 Wall Phone
The early production phones of the Bell company and its manufacturing company, Western Electric, were the 1882 model 3-box wall phones using the Blake transmitter. These phones were large, nearly a metre high. The size was necessary because of the size of the components. The Blake was quite large and needed a box of its own, the batteries were the early glass cell types and were quite bulky, and the magneto generator was tall and heavy and shared the top box with the coil and ringer. A smaller transmitter designed by Berliner was available to the Bell company but it may have caused legal problems with Edison's carbon transmitter so it did not enter production.The invention of Henry Hunnings' carbon granule transmitter in Britain allowed the transmitter to be mounted in the face of the top box rather than in a box of its own. This gave a two-box telephone, but dimensionally it was not much different to the three-box model. The Hunnings was a better transmitter on long lines than the Blake, and the two coexisted for some years. Even though the Hunnings was fitted in such a way that it could be rotated occasionally, its packing problems mean tthat it was never a truly satisfactory transmitter. Packing is where the carbon granules settle to the bottom of the transmitter and reduce its efficiency. Deckert's modification to the Hunnings improved the packing problem slightly, but a new transmitter was obviously needed.
Better transmitters were avaiable from other companies. L M Ericsson had a transmitter that was so well built and compact that it could be used in a handset. Berthon used a large transmitter that also made it onto a handset. Berliner's carbon button transmitter was being made by his own company in Europe.
The Solid Back Transmitter
Anthony White.of Western Electric had been working on the problem for some years, and received Patent No. 485311 for his Solid Back Transmitter on 1st November 1892. (1). This transmitter had minor deficiencies but was used well into the 1930s.
From Herbert and Procter (2)
Left: From Herbert & Procter (2). Detail of capsule.
Poole (6) describes it in detail::
"The small brass cell is provided with a screwed cover, which serves to clamp a small flexible mica disc, to the centre of which is clamped a thin carbon electrode rather smaller than the inside of the brass cell.
This electrode is faced by another one of carbon, fixed to the back of the cell. Both electrodes are electroplated, and soldered to their supports.
The cell is rigidly fixed to the arm, which extends across the instrument. The mica disc is clamped by the the screw shown to a comparatively large ordinary aluminium diaphragm with an india-rubber ring round its edges, held in position and damped by means of two flat steel springs clamped to the rim of the casting, and with their ends tipped with felt or rubber pads, which bear on the outer part of the diaphragm. The sides of the cell are lined with paper, and the space left (between the diaphragms) is filled about three-fourths full with carbon granules. If, however, the transmitter is to be used for common battery working, only about one-half the amount of granules (8.8 grains) is used, in order to increase the resistance.
The diaphragm is 2 1/2 inches in diameter and .022 inches in thickness, and the carbon cell is 5/8 inch internal diameter. The normal resistance of the ordinary instrument is about 30 ohms, and of the common battery form about 55 ohms."
Once set up the transmitter needed little further work during its lifetime. The damping springs were fitted to the mica diaphragm to reduce extraneous noise. This did drop the transmission level slightly, but the extra clarity of speech made up for it. The large aluminium diaphragm agitated the granules slightly, almost removing the packing problem.
There were two main versions. The No. 229 transmitter of 1895 (shown above) had the diaphragm attached by a nut to the carbon capsule, which can be seen if the mouthpiece is removed.
Left: No 323 transmitter , from McMeen & Miller (3)
Both suffered from an internal resonance at about 1000hz, right in the voice frequency range. This caused the voice to sound a bit like a megaphone was being used, but the transmitter was sensitive and transmitted voice well, so this was acceptable. It was not really sorted out until the 1920s. There could also be some carbon noise that sounded a bit like frying or static, especially with new batteries. There were some residual packing problems. but these could be sorted out by tapping the transmitter to loosen up the granules. In all, it was a very good if complex transmitter and Western Electric put it into production.
Mouthpieces were brass or vulcanite, but over the years a number of replacement mouthpieces came onto the market. These were usually "sanitary" types, designed to prevent the spread of tuberculosis germs. They could be boiled, wiped with disinfectant, or were fitted with some sort of sanitary gauze or paper that could be thrown away after each use. Some carried advertising, and all are now rare.
With the increasing cost of materials and the introduction of dry cells to replace the old glass wet cell batteries, it was an appropriate time to redesign the telephone into a smaller more economic unit.
The 317 Series
The phone that resulted was given the model number 317. It was introduced in 1907. There were many changes, updates and modifications during the life of the phone. In its original form it had a "Cathedral Top" case with a "Picture Frame Front" , the old type 122 "pony" receiver with exposed terminals, and terminals and lightning arrestor at the top of the case. Although the case was basically a plain box, it was made from well-finished oak or walnut. The nickel plated metalwork made it a rather handsome phone.
Internally , solid wire was used. Insulated sheaths were simply slid over wires
where they were exposed. Incoming line wires were routed into narrow sawcut
grooves in the rear of the backboard, and usually waxed to reduce corrosion.
The wires to the transmitter were soldered to the hinges, which were on the
right of the case.
Internal view showing the large magneto generator. Later model.
From the start, the 317 was designed as a party line telephone, to suit as many conditions as possible. This gave rise to a large number of versions, some of which will be detailed later. The following description is from Western Electric's 1912 catalog.
Magneto Signalling System
In the code ringing system, a large number of parties may be connected to one line, all of the ringers at the telephone stations and the central office drop being bridged across the line. Whenever a party on the line operates his hand generator, all of the ringers in the other telephone sets and the central office drop are operated. When the central office operator rings on the line, all the bells are sounded. The party wanted is called by a code system made up of various numbers of long and short rings.
In the harmonic selective ringing system, selective signalling is secured by properly tuning the ringers to operate on different frequencies. Four frequencies on a constant voltage are used, 16 2/3 cycles, 33 1/3 cycles, 50 cycles and 66 2/3 cycles. Special keys are provided at the switchboard so that either four parties with bridged ringers or eight parties with grounded ringers can be signalled selectively. For outgoing calls, the central office only can be selected.
In the four-party selective ringing system using pulsating current, four telephones may be connected to a metallic circuit and signalled selectively. The ringers in these telephone sets are biased, and two ringers are connected to ground from each side of the line. One ringer on each side of the line is arranged to operate on negative pulsating current. The cord circuits at the central office are so wired that positive or negative pulsating current may be sent out over either side of the line to ground by means of a special key for each cord circuit or a master key for an operator's position.
The center checking system is used on toll lines when it is desired to have several stations on one line and yet require all of them to secure connections through one office. The ringers at the stations are all biased one way and bridged across the line. They are operated from the central office either by alternating current or by pulsating current in one direction only. The generators at the stations are all arranged to furnish pulsating current of the polarity which does not ring the bells, and accordingly it is impossible for one party on the line to call another except through the center checking operator. The central office has a bridged drop operated by the pulsating current, and the central office operator signals the parties on the line by means of a code system.
In the selective central office signalling system, a large number of subscribers may be connected on one line and arranged so that they can call each other without signalling the central office, or they may call the central office without notifying the other parties on the line. This is accomplished by bridging the telephones across the line and wiring them so that the generator is normally connected to the two sides of the line, but may be switched by the subscriber so that it is bridged between one side of the line and ground. At the central office, the drop is connected between one side of the line and ground.
If the subscriber operates the generator in the usual way without operating the switch, he will ring the other bells on the line. If, however, he operates the switch before turning the generator crank, he will throw the drop at the central office and the bells on the line will not sound. Some telephone sets are equipped with push buttons for signalling the central office, and other sets are provided with extra contacts on the switch hook, so that if the generator crank is turned after the receiver has been removed from the switch hook, the central office will be called.
It can be seen from this that party lines were an essential part of the construction of telephone lines in the United States. This was partly an economy move, and partly because of the capital cost of erecting extra lines to service an area. A similar situation existed in Australia, although party lines were restricted to a maximum of ten parties using code ringing. Many railways worldwide found the system attractive, and the Western Electric phones were widely used on them.
Left: Closeup of the generator, earlier type.
Above left: Bell adjustment, No 38 ringer
Right: Armature adjustment.
In the 1909 update insulated wire was introduced., and the wiring at the back was moved inside the case. The Cathedral Top disappeared in the interests of economy, but the Picture Frame Front was retained. Metalwork was still nickelled, although a frosted finish was introduced in small numbers. The enclosed-terminal No. 143 receiver was introduced. The door hinges were moved to the left side of the case.
In 1911 the case size was shortened slightly and the Picture Frame Front was dropped. Three hinges now held the door. The transmitter was wired directly to the internal circuit using the new stranded flexible copper wire, rather than soldered through the hinges with solid wire.
In the 1916 update the new 323 "bulldog" transmitter on a short steel bracket was introduced. This finally did away with the long transmitter arm. The slope of the writing shelf was made steeper to compensate. The phone was available in two sizes to handle two or three cells from about 1918. A wiring diagram was included to show circuit changes needed to convert the phone to CB operation, using the inbuilt capacitor. CB exchanges were being introduced in increasing numbers, and it made economic sense to just convert the phone rather than replace it. By 1918 a larger number of the phones appeared with black-painted or frosted nickel bells, an economic necessity brought about by the demands of World War One.
1938 saw the bakelite "Bulldog" mouthpiece on an F1 transmitter and the model number changed to 417. The receiver included the new HA1 receiver module that had been introduced in the bakelite F1 handset in 1936. The No 113 anti-sidetone coil was improved, and the final phone was as good as any produced. In spite of this, the bakelite phones offered major economies in production and the 317's days were numbered. There was one final update. The No.SP 417 was a 317 adapted to take a bakelite handset. A blanking plate covered the transmitter hole. The phone continued in production in Canada for some further years, but apart from some small production runs carried out for the U.S. military up to 1945, production turned to bakelite phones.
Western Electric used a rather complex numbering system based on the parts used in the phone. A "1" in front of the model number denoted a complete telephone Other numbers and letters were added as appropriate. This table is from Ralph Meyer's "Old Telephones" lists most U.S. models.
Instead of code ringing, the 317 could be supplied set up for harmonic ringing on party lines (using ringers tuned to different frequencies so only the called phone would ring).
1317Y with 33 1/3 cycle ringer of 460 ohms, 3-bar generator
1317AA with 50 cycle ringer of 460 ohms, 3-bar generator
1317AB with 66 2/3 cycle ringer of 460 ohms, 3-bar generator
1317AC with 162/3 cycle ringer of 1800 ohms, 3-bar generator.
1317AK for "Heavy Load" service, 2500 ohm ringer, 5-bar generator
1317AU for light load service, with 2500 ohm ringer and 3-bar generator
1317AT for moderate loads, with 1600 ohm ringer and 5-bar generator, designed to work with a more sensitive drop shutter at the central office (telephone exchange)
1317AY for moderate loads, as above but without the more sensitive signalling. 5-bar generator.
1317BA as above, with a pushbutton for selective central office signalling.
1317AJ Four-party telephone with 2-bar generator and polarised ringer
1317 AM for series service, 3-bar generator
A different numbering system was used in the British W.E. factory
A catalog from the 1920s lists the version without the Cathedral Top, but still with the Picture Frame Front and outside terminal receiver, as:
No 40060 Polarised Ringer 3-bar generator 1600 ohm resistance No Condenser 2-cell case For 20-mile line, up to 30 telephones
No 40061 Polarised Ringer 3-bar generator 2500 ohm resistance No Condenser 2-cell case For 25-mile lines, up to 40 telephones
No 40062 Polarised Ringer 3-bar generator 1600 ohms resistance Condenser 2-cell case For 20-mile lines, up to 30 telephones
No 40063 Polarised ringer 3-bar generator 2500 ohms resistance Condenser 2-cell case For 25-mile lines, up to 40 telephones.
The condenser across the line was to provide continuity in a party line circuit if a receiver was accidentally left off the hook. Note the number of telephones that can be connected on a party line. These phones were sold from the British factory to many former colonies such as Australia. They were particularly popular with railways administrations due to the large numbers of phones that could be handled on a long line. British Post Office practise, as followed by many telephone administrations, was to allow no more than ten parties on a line. The Australian Post Office preferred the Commonwealth Ericsson and later the N2500 models for this use.They bought many 317s however to make up for shortages and for use on private lines.
1. Meyer R. "Old Time Telephones" 1995
2. Herbert T E & Procter W S "Telephony Vol 1" London 1932
3. McMeen S and Miller K "Telephony", Revised Edition, Chicago 1923,
4. British Western Electric catalog, 1920s, undated.
5. U.S. Western Electric catalogs, various.
6. Poole J "The Practical Telephone Handbook" London, 1912