Model 102 telephone

The model 102 telephone was a version of Western Electric's first widely distributed telephone set that featured the transmitter and receiver in a common handset. Although this type designation was not used before ca. 1930, predecessor types were produced starting approximately in 1927 with the A handset mounting. Earlier telephones by Western Electric had been of the candlestick type which featured a transmitter fixed to the base, and a receiver held by the user to the ear. The design of the A handset mounting was inherited from the candlestick desk stands, while the B handset mounting was slightly reshaped. The B type was produced between 1928 and 1932. Later models, the D handset mounting, starting in 1930, used an oval foot print to improve physical stability during dialing.

The model 102 telephone consisted of the handset mounting typically placed on the desk top and a physically separate desk set box or subscriber set. This box was typically mounted on a wall near the phone or on the side of a desk. The desk set contained only the dial, a handset cradle with hook switch, and the handset positioned in the cradle, while the subscriber set contained the ringer and the electrical components to interface the unit with the telephone network.

The 102 telephone was plagued by problems with excessive sidetone, resulting in a poor experience for users hearing their own voice very loudly, and in extreme cases in early versions also unstable feedback from the receiver into the transmitter. This resulted in users lowering their voice to the point where the other party found them difficult to hear. This problem was resolved when the 102 was upgraded in approximately 1930 to the 202 telephone.

As early as 1890, Western Electric had been experimenting with handset types that combined the transmitter and the receiver in the same hand-held unit, but two technical problems prevented them from reaching production at that time. First, the transmitters of the day did not work well unless oriented in a vertical plane. If operated at other angles, as would be expected in a hand-held unit, carbon granules in the transmitter would shift and move in an unacceptable manner, resulting in poor voice quality, referred to as carbon noise.

Another hurdle to the acceptance of a common handset model was that audio from the receiver was picked up acoustically by the transmitter and amplified, resulting in howling tones, called acoustic feedback, due to the hollow handles providing an acoustic channel between receiver and transmitter. The problems were aggravated by the signal boosting circuitry used in the subscriber set which resulted in a strong signal (sidetone) at the receiver of the speech of the user. Sidetone is desirable only to some fraction of volume so that the user has the assurance that the telephone is working correctly. Strong sidetone may cause users to lower the voice to unacceptable levels, so that the recipient receives insufficient signal level.

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