DBH 9001 (replaces CP 100)
This device contains a radio amplifier circuit. This telephone is intended for use by people with disabilities, hearing ability and also on wires with poor transmission properties. For the latter purpose the device also amplifies the outgoing speech. Maximum the gain for incoming speech is about 2.3 neper and the gain can be regulated by a potentiometer, with a control knob located in the lower right corner of the device.

To avoid distortion, the incoming the level not be higher than -1.3 nepcr. For outgoing numbers is usually set to zero level. For wires with bad transmission characteristics, the apparatus can be adjusted to give a certain positive level by switching the sockets on the secondary winding of the transformer REK 10202.

In this way the gain can be regulated 0.8 neper in step of 0.2 neper. The highest possible output level is thus +0.8 nep.

The device has a black Bakelite cover. For the appliance a battery BKA 1004 of 1.5 Volts and one is required battery BKA 1501 at 60 Volts. A suitable battery box for these are BKY 1004.

Parts:
Microphone RLF 1024 made of black Bakelite with microphone capsule RLA 1004, 40ohms, and Cord TRS 1401, 1250mm.
Marconi tube L11, (two).
Transformer REK 10201.
Transformer REK 10202.
Transformer REK 10203.
Capacitor RKA 7121, 1+0.12uF.
Line cord TRS 1102, 1250mm.
Wall case made of black lacquered sheet metal with:-
Capacitor RKA 1010, 1uF (two).
Ringer of 1000ohms, consisting of: mechanism KLA 1064.
Bell gong with low tone 138 543/1.
Bell gong with high tone 138 543/3.

Dimensions:
Height 139mm, width 233mm, depth 178mm.

Weight 3.6 kg.
 

Taken from the L. M. Ericsson Catalogue No. 610 (1939) - Swedish Translation

Last revised: March 21, 2024