Ericsson DIALOG - Transmission Unit

3.3 Transmission unit
10
-5 2
70
dB rel. 2 · 10 N/m
hll
511
40
0
JO
IS
20
kH z
Fig. 10 Rin ger output sp ectru m
The printed board is made of insulating material. On the rear
side there is a printed wiring , which connects all the component s
in the transmission unit. The components are gro uped on the
other side , bell and dial and cords being connected to the board
with screw terminals.
The transmission unit (fig. 11 ) comprises induction co il , resistors,
capacitors and varistors as well as crad le -swit ch springset.
Details of these components are given in the following.
Fig. 11
The trans-
mission
un it
3,3.1
Ind uction coi l
The induction coil (fig. 12) is of the antisidetone type with five
windings and a C-core of laminated silicon iron, protected against
rust by means of varnish. This design has resulted in hi gh
permeabilit y and an imp ortant saving of material. High inductance
values have been ob tain ed wit h moderate copper loss es, and the
very good coup lin g between the winding sections results in a high
sid eto ne attenuation.
(1
!l
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