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Bordverständigungsanlage (Intercom System)

As soon as radios become part of vehicular installations, intercom systems turn up. They allow not only the use of the radio from different positions in the vehicle, but also the internal communication between crew members. In a tank for instance, where part of the crew is located in the turret and other personnel will be in the main body a necessity. But other vehicles also have different compartments - and high noise levels...

An intercom system comprises different parts. Sometimes - like with these SEM's - there will be a separate audio amplifier. Always you will find control boxes, hooking individual crew members into the system. Sometimes there will be also specialized control boxes, like the one governing communications to a handset on the outside of the vehicle. In the case of these SEM's this is done through a separate box outside the vehicle, that also allows communications to other vehicles over field wire as well as hooking up the remote control set.

 BV-Verstärker - Bordverständigungs Verstärker (Intercom Amplifier) Vers.-Nr. 5830-12-141-1250

The intercom amplifier amplifies the microphone- and receiver signals for the headphones on the on-board communications control boxes. Transceivers and intercom can be heard simultaneously. The switch on the short side of the housing is meant to switch the amplifier on or off, when no transceiver is in use. In the off position (O) the amplifier will be switched on automatically when a connected transceiver or receiver is switched on through it's transceiver control box. The amplifier will only be switched off with the radio installation. If the amplifier is used without a radio installation, purely for intercom purposes, this switch switches off the intercom.
The intercom amplifier delivers from the 24 Volt the stabilized 6 Volt for the carbon microphones or the transistor amplifiers of the dynamic microphones.
Originally mounted on it's own Schwingmetallrahmen (shock mount) - mostly missing in surplus. Nomenclature and further data of this shock mount unknown. No electronics inside this shock mount.
External controls and connectors
Switch 0/- (Internal: S1)
Connector 2: Power in, from Überspannungsschutz. (Internal: P2)
Connector 51: (Internal: unmarked) Signals and controls, to Grundplatte
Connector 9: (Internal: J2) Signals and controls, to BV-Bediengerät
Connector 9: (Internal: J5) Signals and controls, to BV-Bediengerät
Connector 9: (Internal: J6) Signals and controls, to BV-Bediengerät
Connector 71: (Internal: J3) Ortsbesprechgerät (Local Communications Control Box) or Lautsprecher (Loudspeaker)
Connector 72: (Internal: J4) Ortsbesprechgerät (Local Communications Control Box) or Lautsprecher (Loudspeaker)
Fuse (1A) (Internal: SI1)
Pressure equalizing screw
Technical data
Audio voltages from all receivers, amplifier input: 5,5 V (600 Ohm, 50 mw)
Microphone voltage, amplifier input: 0,25 V (150 Ohm)
Audio output for all three channels: 1 Watt (600 Ohm)
Audio frequencies: 300 to 3400 Hz
Voltage: 24 V, negative earth, maximum voltage 32 V
Power rating at 24 V
    without amplification and without microphone current: 160 mA
    with amplification (3 x 1 W); without microphone current: 460 mA
    with amplification (3 x 1 W) and 150 mA microphone current: 610 mA
Microphone voltage: 6V, stabilized
Height: 119 mm; Width: 262 mm; Depth: 220 mm; Weight: 6,90 Kg
A description can be found in TDv 5820/045-13, page 7, complete with photograph.
The B.V. Verstärker consists of a light metal (aluminium?) box. As the individual parts do not show Vers.-Nr. this unit seems to be meant to be exchanged as a whole, no replacement of parts was done in the lower echelons.
This box contains all the external connectors, fuse, switch and tied down wiring, as well as an internal connector marked J1 (14 female, three rows) that connects the actual electronics that are contained in their own separate module.
The type plate reads:
Gehäuse B.V. (housing B.V.).
SEL. Typ: SEM 25. Werk Nr.: X XXX XXXXX. Auftr-Nr.: FG II 5a/01/11810/010/3
Internally it is marked: 5800410-0051.001.1  Alu 31.3906
The box has a separate lid, fastened with four screws, with water tight rubber seal.
The type plate reads:
Deckel B.V. (Lid B.V.)
SEL. Typ: SEM 25. Werk Nr.: X XXX XXXXX. Auftr-Nr.: FG II 5a/01/11810/010/3
Internally it is marked: 5800410-0051.001.1   Alu 31.3905
Apart from wiring, connectors, fuse and switch all electronics are contained in their own plug-in modules. It seems to contain a three channel amplifier, with a fourth master channel. Four trim pots are accessible through holes in the cover.
The type plate reads:
Einsatz B.V (Insert B.V.)
SEL. Typ: SEM 25. Werk Nr.: X XXX XXXXX. Auftr-Nr.: FG II 5a/01/11810/010/3

BV-Bediengerät - Bordverständigungs-Bediengerät (Local Communications Control Box) Vers.-Nr. ?

The BV Bediengerät is the local communications control box - up to six of these may be part of an installation. Each one has two audio connectors number 41, normally used with headsets or handsets, with individual loudness controls. The two connectors number 9 are either to connect the control box to the BV-Verstärker (on board communications amplifier) or to hook up the next control box.
The three position switch on front (Wahlschalter) controls the scope of both audio connectors:

Position I:               Listen to Transceiver I and local communications; transmitting from Transceiver I
Position BV, I-II:    Listen to Transceiver Iand II and local communications; no transmitting
Position II:              Listen to Transceiver II, Receiver and local communications; transmitting from Transceiver II

The transmit-switch (Sendeschalter) on top has two positions. In the neutral middle position no transmissions are possible, all communications are strictly local. In the right position - that can be locked but normally immediately returns to the middle position - the transmission circuits on both transmitters are accesible.

As the amplifier delivers 1 Watt for each of the three channels (9-9 cables) it seems prudent to balance the load over the different control boxes. The schematics found in some manuals seem to adhere to this, the maximum number of control boxes to one 9 outlet on the amplifier is two. However, the extra vehicular control box can in some cases be added to the end of a chain of two control boxes.

External controls and connectors
Switch: Wahlschalter
Switch: Sendeschalter
Volume Control Lautstärke (2x)
Connector: 9 (2x) BV-Verstärker or BV-Bediengerät
Connector: 41 (2x) Audio accessories
Height: 169 mm; Width: 162 mm; Depth: 72 mm; Weight: 1,97 Kg
A description can be found in TDv 5820/045-13, page 8, complete with photograph.

Außenbord-Bediengerät (Extra Vehicular Control Box) Vers.-Nr. ?

Communications with persons outside of the vehicle is possible through the combination of the Außenbord-Bediengerät (Extra Vehicular Control Box) and the Außenbord-Sprechstelle (Extra Vehicular Telephone).
The Außenbord-Bediengerät is mounted within the vehicle and hooked up by a 41-41 cable to a BV-Bediengerät, also taking the place of a normal audio accessory. Connector number 11 hooks the Außenbord-Bediengerät up to the actual Außenbord-Sprechstelle, that is mounted on the outside. The Außenbord-Bediengerät also has it's own power connection, directly to the battery, through connector number 12.
Apart from enabling communications to the handset provided outside the vehicle, the Außenbord-Bediengerät also governs the Panzer-Panzer communications. Two vehicles can be connected through field cable and then are able to communicate without radio.
Also, in complete systems the Ortsbesprechgerät will be connected by field cable to the Außenbord-Bediengerät. This signal is then available on the Außenbord-Sprechstelle as a simple way to hook up the Fernbesprechgerät.
External controls and connectors
Switch: BV Panzer-Panzer on/off
Switch: Außenbord-Sprechstelle on/off
Connector: 11 To Außenbord-Sprechstelle
Connector: 12 Power
Connector: 41 To BV Bediengerät
Clamps: Ortsbesprechgerät
Lamp: Signals when the PTT on the handset connected to the Außenbord-Sprechstelle is pressed
Height: 154 mm; Width: 162 mm; Depth: 72,5 mm; Weight: 1,82 Kg
A description can be found in TDv 5820/045-13, page 9, complete with photograph.

Außenbord-Sprechstelle (Extra Vehicular Telephone) Vers.-Nr. ?

External controls and connectors
Volume Control Lautstärke
Connector: 11 To Außenbord-Bediengerät
Connector: 43 Handset
Clamps: Field cable to other vehicle (Panzer-Panzer)
Clamps: Field cable to Fernbesprechgerät
Height: 142 mm; Width: 130 mm; Depth: 126 mm; Weight: 2,33 Kg
A description can be found in TDv 5820/045-13, page 9, complete with photograph.

Last updated: 17-06-2005 10:25 +0200
Copyright © 2001, 2002, 2003, 2004, 2005 A.J.M.O. Witkop. All Rights Reserved.