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325.jpg (13186 bytes)This instrument is of the ordinary size and fitted with a fixed transmitter No. 570, receiver No.546 with cord No. 2030, four-magnet generator No. 479 which will ring satisfactorily through the 150 ohm bell of the instrument and a line resistance of 15,000 ohms, and also a battery box to accommodate two cells No. 591 or 972.

The instrument is intended to be used when several instruments are to be connected to the same line. It differs from the preceding instruments by being provided with a three-way lever switch. By pushing the lever to the left or to the right communication can be established with the corresponding side of the line.

A third line can also be connected to the instrument, and when the lever is in its vertical position this line is connected to the instrument. The bell will then not ring for a through signal, and conversation can be established between the other instruments and cannot be overheard. In order that it shall be possible to call the instrument from the third line, an extension bell No. 426 must be connected between the terminals L' and J (in shunt on the third line). The third line cannot ordinarily be connected with the two main lines. This can, however, be made possible by using switch No. 460.

Weight 17.4 lbs. Price £4 1 0s.

Later renumbered as the AD 100.

Taken from the Ericsson Telephone Catalogue 1903 and also in the 1897 Catalogue

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Last revised: September 30, 2019