Ericssons pioneered the handset in commercial production
with their skeletal desk telephone. There were four main styles of transmitter
used on the handsets, and some specialty models. The cords were plaited silk covered
wire, usually green or brown. By the time of the tin box desk models the
cord was made of twisted wires inside a cotton sheath.
:Fig 1: We will call this Type 1 for convenience. It is a flat cylinder style about 15mm deep. Most had a raised edge around the top and bottom. Finished in nickel. Used from 1892 to about 1903. The handset was wooden with large grooves, later replaced by ebonite. :
Fig 2: Type 2 is slimmer with a series of steps forming a dome. Nickel finish. Introduced about 1902, with a new handset grip of ebonite with fine grooves.
Fig 3: Type 3: A deeper dome shape. It is usually found on the later desk sets. The handgrip was ebonite, but emergency post-World War 1 models are known with a plain wooden grip.
Fig 4: Type 4 is better known as the Sanitary Transmitter. A cap over the tranmitter prevented germs and noxious vapours collecting in the mouthpiece and spreading disease. It was optional across almost all the model range. It seems to have been the transmitter of choice for the New Zealand Post Office.
Replacement Transmitters were developed by Ericssons to upgrade the earlier transmitters on other brands of phone, especially those of Bell and Western Electric.
Fig 5: Number 575 on the left is a carbon granule transmitter designed to replace Bell's Blake transmitter .
Fig 6: The No. 576 on the right is similar and uses a basic mount for fitting to new phones. Both were deigned to be rotated occasionally to loosen up the carbon granules.
Pulpit transmitters were designed to be mounted vertically on wall phones. The concept of a separate transmitter and receiver quickly gave way to the more popular handset.
Fig 7: the original "spiral" coal grain transmitter was set horizontally on an ornate mounting which reduced packing of the carbon grains. It was also used briefly on some early desk phones.
Fig 8: is the early mass production model. The new transmitter could be mounted vertically, but the ornate mount was retained.
Fig 9: , a less ornate version introduced about 1892. It was quickly replaced by
Fig 10 , mounted straight onto the front of the phone.
Fig 11 is the replacement transmitter used to upgrade other companies' phones
Fig. 12 is the rare three-arm adjustable mounting used on only a few models.
Long Arm (or Gooseneck) transmitters were not widely used in Europe but proved popular in the United States. In Britain they were used on some early British Post Office models. They were introduced about 1892.
Fig 13 has a larger base which allowed the induction coil to be built in. As well as the early transmitter shown, they also used a deeper "Drum Transmitter" which was soon replaced by the Solid Back transmitter.
Fig 14 is the later version, based on a plainer Western Electric model. This illustration shows the Solid Back transmitter.