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AEG Telefunken SE-6861   LAPR
Long-distance HF manpack radio

SE-6861 is a military manpack radio station, developed in the early 1970s by AEG Telefunken in Ulm (Germany) as part of a range of military radios. Strickly speaking it was not a spy radio set, but it was heavily used by Special Forces (SF), often in combination with secure message devices.

The SE-6861 measures 315 x 300 x 92 mm and weights 8.5 kg (batteries included). It consists of two parts: the actual transceiver and a removable battery pack, which its mounted at its bottom. It was usually supplied in a green carrying case that also had space for some of the accessories.

Except for the battery charge socket, all controls and connections are located at the front panel, with the frequency setting buttons protected by a hinged lid. It covers the entire 1.5 to 30 MHz frequency band in 100 Hz steps and offers an output power of 2 or 20 Watts, in
LSB
or
USB
.
  
SE-6861 with handset connected

The transceiver was suitable for a 30 to 1500 km operational range and was the standard radio set of many Special Forces (SF) world-wide during the 1980s en 1990s, such as with the German Fernspäher and the Dutch Commandos. In The Netherlands it was known as LAPR, which is short for Lange Afstand Ploeg Radio (Long Distance Group Radio). The radio was in production until at least 1989, and was replaced in the late 1990s by modern Harris radio sets, and later by SDR.

Carrying case SE-6861 with cover open SE-6861 with handset connected SE-6861 with handset and EMU SE-6861 with detached battery pack Front view Front panel Multi-segment antenna
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Carrying case
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SE-6861 with cover open
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SE-6861 with handset connected
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SE-6861 with handset and EMU
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SE-6861 with detached battery pack
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Front view
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Front panel
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Multi-segment antenna

Versions
  • SE-6861/11
    Initial version,
    SSB
    (without
    LSB
    /
    USB
    selection)
  • Basic version with
    ATU
    , no remote control
  • SE-6861/22
    Basic version without
    ATU
    , no remote control
  • SE-6861/32
    Basic version with
    ATU
    , remote controllable
  • SE-6861/42
    Basic version without
    ATU
    , remote controllable
  • E-6862/02
    Receiver-only version
  • SE-6863
    100W version, with external
    PA
    and
    ATU
SE-6861/12 mod
Operation of the SE-6861 is really straightforward. The MODE-selector at the top center is used to turn the set ON and OFF and to select the desired MODE of operation. The user can select between
USB
and
LSB
, and between voice (J3E) and
CW
(A1A). Another selector, at the bottom left, is used to select the appropriate antenna (rod, wire or external) and the desired RF output power (2W or 20W). The built-in antenna tuner is used in combination with a rod or a wire antenna.

Front panel of the S-6861/12 mod. Click for a better view.

The current frequency can be set with a series of UP/DOWN push-buttons at the right, in steps of 100 Hz. Another UP/DOWN selector, to the left of the MODE selector, can be used to select one of four memory channels. Setting this selector to 0 (zero) selects the current frequency. Any of the other memory locations can be programmed, using the PRESET button at the bottom right.

A suitable handset or headset can be connection to any of the two sockets at the right. These sockets can also be used for the connection of a message unit or a crypto device. An external antenna can be connected to the BNC socket at the top left. When operating the radio in the dark, the orange push button at the center of the ANTENNA/POWER selector can be used to turn on scale illumination. Audio volume can be set in 7 steps using another set of UP/DOWN buttons.


Parts
Carrying case AEG Telefunken SE-6861 transceiver Muli-segment antenna Handset with PTT switch Headset with microphone and PTT Battery pack Various cables Electronic Message Unit (EMU)
EMU
Message Entry and Read-Out Device Message terminal
Carrying case
The radio was commonly supplied in a green watertight storage case that could be carried on the back. In order to reduce weight, the internal frame that protects the radio against severe shocks, is made of lightweight foam.

The case has two narrow pockets at the sides – one for the handset and one for a multi-section atenna – and a wide one that can hold cables and documentation.
  
Carrying case

Transceiver   SE-6861
The image on the right shows the actual radio, with the standard rechargable battery pack installed at the bottom, held together by two spring-loaded clamps. The power socket is located just below the rightmost clamp.

The front panel is shown here with the hinged cover – that protects the frequency setting push buttons – open. At the right are two sockets for the connection of headset, handset and EMU.
  
SE-6861 with cover open

Antenna
The radio has two terminals for the connection of an antenna. An external one can be connected to the 50 Ohms BNC socket at the front panel, whilst a local one can be installed on the large screw terminal just below the BNC socket.

Several types of antenna were available for the SE-6861, such as the multi-section foldable one shown in the image on the right. When unused, it can be stowed in a pocket of the carrying case.
  
Multi-segment antenna

Handset
In most cases, the SE-6861 was used with the common handset shown in the image on the right. it has a standard plug – NF07 in this case – for connection to the radio.

Note that some international versions of the SE-6861 had different audio connectors.
  
Handset

Headset
Although a purpose built headset was available for the SE-6861, many users preferred the Racal one shown in the image on the right, because of the better audio quality.

In this case, the Racal headset is wired with an NF-07 plug, that can be connected directly to one of the audio sockets at the right side of the front panel.
  

Battery pack
The SE-6861 is usually powered by a 30V battery pack that is attached at the bottom of the radio. Different types of battery used to be available.

When installed, the battery connects directly to the radio. Furthermore it has a power socket at the right side, through which the radio can be powered and the battery can be charged. This socket accepts a 19 to 38V DC input. It takes approx. 14 hours to charge the batteries.
  
SE-6861 with detached battery pack

Cables
The cable shown in the image on the right was used for charging the batteries, by connecting it to a 19 to 38V DC power source. The charging current should be approx. 200 mA.

Other cables were available for connection of an Electronic Message Unit (EMU) and for external power souces, such as the battery of a vehicle.
  
Power cable

Electronic Message Unit   EMU
The SE-6861 was often used in combination with an Electronic Message Unit (EMU) for encrypted exchange of messages, such as the Nokia PARSA (Partiosanomalaite), shown here. It is also known as the Philips UA-8296, and allows messages to be prepared and encrypted off-line.

Once the message is complete, it is transmitted in encrypted form, at very high speed (a burst transmission), in order to minimise the risk of detection and radio direction finding (RDF).

 More information

  
Nokia PARSA

Digital Message Device   DMD, MEROD, TDED
In the UK and in The Netherlands, the SE-6861 was often used with a Racal Message Entry and Read-Out Device (MEROD), such as the MA4248, the MA4450 and the MA4480. For the US Army, Racal developed a special version of the MEROD, that was known as the KY-879/P.

The image on the right shows a typical Racal MEROD unit — the MA-4450 — with was used in combination with a variety of military radio sets, including the SE-6861. It is shown here in its protective nylon carrying bag with the optional illumination lid installed and opened.

The bag has several pockets for holding the various cables, accessories and a junction box. They can be packed in such a way that the entire unit is ready for use at any time. For a long time, MEROD devices were standard issue with Special Forces (SF) in many countries.

 More information

  
MEROD MA-4450 in carrying pouch, with lid open

Telestar
The SE-6861 was sometimes used with the Telefunken Telestar 121 or 122, either in clear or with the TELEKRYPT DAT-812 encryption unit.

Telestar was a compact rugged teleprinter with a built-in thermal printer and (optionally) a radio interface. It was used by the German Police, the Bundesgrenzschutz (BGS) and NATO.

 More information

  
Telefunken Telestar 121

SE-6861 carrying case Carrying case Carrying case SE-6861 inside carrying case Radio inside foam frame Handset stowed in a pocket of the carrying case Inzipped pocket reveals power socket Antenna stowed in a pocket of the carrying case
Multi-segment antenna Handset SE-6861 with cover open SE-6861 with detached battery pack Battery pack power socket Power cable Handset and EMU connected to the radio MEROD
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SE-6861 carrying case
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Carrying case
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Carrying case
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SE-6861 inside carrying case
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Radio inside foam frame
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Handset stowed in a pocket of the carrying case
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Inzipped pocket reveals power socket
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Antenna stowed in a pocket of the carrying case
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Multi-segment antenna
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Handset
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SE-6861 with cover open
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SE-6861 with detached battery pack
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Battery pack power socket
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Power cable
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Handset and EMU connected to the radio
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MEROD

Dutch Special Forces
In the Netherlands, the SE-6861 was introduced in the early 1980s, with the Special Forces (104 Waarnemings- en Verkenningscompagnie). It was called LAPR, which is short for Lange Afstand Ploeg Radio (Long Distance Group Radio) and was given the internal designator KL/TRC-5151.

The SE-6861 was used in combination with a Racal MEROD crypto unit, either the MA-4248, the MA-4450 or the MA-4480 which was given the designator KY-55590/TGC-5551. The common Dutch name for it was DBA, or Digitaal Berichten Apparaat {Digital Messaging Device).

The SF 104 used this rig to operate from behind enemy lines, after infiltration during the night or after having been dropped as a parachutist. They would hide themselves underground and operate from there. They often used inconspicious NVIS wire antennas, such as the well-known WINDOM.
  
Dutch Special Forces using MEROD in the field

The image above shows a Dutch Special Forces soldier in an underground hideout [1]. The soldier in the picture is entering a message on his MEROD device (DBA). The SE-6861 (
LAPR
) is visible in the top right. Note that the version used by the Dutch, has U-299 connectors rather than NF07.

Messages were first converted into a series of short messages – typically with a manual system like Slidex or Batco – and were then encrypted and transmitted in
AFSK
by means of MEROD.

The radio was operated in an acurate time and frequency scheme, which was very difficult to predict for an outsider. As a result, the radio station was very dificult to intercept and locate.

All messages were monitored and recorded in a central listening post comprising a few radios, a PC and Racal's Message Base Station MA-4420.
  
Dutch special forces using MEROD in a command center

In the Netherlands, the MA-4420 base station was known as KY-5589/TGC-5578. Messages could be printed onto paper, for further handling by intelligence officers (INTEL). The photograph above shows the same MEROD device (
DBA
) in use in a Dutch command center [1]. In the early 2000s, the Dutch Special Forces dropped the SE-6861 in favour of Harris radio equipment.

Dutch Special Forces using MEROD in the field Dutch special forces using MEROD in a command center
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Dutch Special Forces using MEROD in the field
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Dutch special forces using MEROD in a command center

Interior
The SE-6861 is housed in a strong lightweight die-cast aluminium enclosure, that consists of a front panel and a case shell. The two parts are held together by six screws around the edges of the front panel. All internal parts are mounted into a frame that is attached to the front panel.

After loosening the six bolt at the edges of the front panel, the entire contents of the device can be extracted from the case shell, as shown here. The olive green front panel is facing away here.

The device comprises a large motherboard at the bottom, into which a number of modules are plugged. Some of these modules (in particular the synthesizer and the RF power amplifier) are part of the construction. At the top center is a removable stainless steel bracket with five holes, that serves as an extractor for the modules. It can be slotted into the top of each module.
  
SE-6861 extracted from case shell

Note that some modules are not only interconnected via the motherboard, but also at the rear, by means of a series of teflon coaxial cables with SMB connectors. They should be unplugged before removing a module. Also at the rear is a 10-pin power socket for connection to the battery pack.

Note that the pinout of this connector is quite different from the (identical) power socket at the side of the battery pack. It should not be used to power the radio directly. Instead, power should always be applied via the battery pack socket.

Most modules – with the exception of the power amplifier (PA) and the front panel – are housed in an aluminium can, with a removable lid that is held in place by four sealed screws. Inside each can is one or more printed circuit board (PCB). As an example we are showing the two PCBs of the memory module in the image on the right.
  
Memory module interior

According to date codes on the various components, the device shown here was manufactured in the late 1980s, probably in 1989, although most parts were made five years earlier, in 1984. As most SE-6861 units are now well over 30 years old, it seems logical to assume that the batteries will now be exhausted and can no longer be charged. Luckily, the battery pack is fully acessible and various initiatives on the internet demonstrate how the batteries can best be replaced [2][3].

SE-6861 extracted from its case shell SE-6861 extracted from case shell Bottom side Modules SE-6861 with extractor mounted on a module Using the extractor to pull-out a module Memory module interior Poewr socket at the bottom (mates with battery pack)
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D
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SE-6861 extracted from its case shell
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SE-6861 extracted from case shell
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Bottom side
D
4 / 8
Modules
D
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SE-6861 with extractor mounted on a module
D
6 / 8
Using the extractor to pull-out a module
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Memory module interior
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8 / 8
Poewr socket at the bottom (mates with battery pack)

Connections
Audio NF07
The SE-6861 has two identically wired audio sockets at the right hand side of the front panel. On the standard (German) version of the radio, these sockets are of the NF07 type, and are wired for a standard handset with NF07 plug. Here is the pinout when looking into one of the sockets:

  1. Audio out 0dBm/600Ω
  2. Speaker
  3. Microphone (1)
  4. PTT (or morse key)
  5. connected to 'E' on other socket
  6. Microphone (2)
  7. Ground
Audio U229
One some international versions of the SE-6861, such as the ones used by the Dutch Special Forces, the NF7 audio sockets were replaced by U-229 sockets, which was the common standard within the US armed forces and within NATO. Below is the pinout when looking into the socket:

  1. GND
  2. Speaker
  3. PTT
  4. MIC
  5. not connected
Power
Below is the pinout of the power socket on the right side of the battery pack, when looking into the socket. Note that this connection can be used to power the radio directly (by using pin D/E), or to charge the battery (using pin C/J), whith the (-) terminal always connected to A/B/H.

  1. GND
  2. GND
  3. Charge (+) 21.5 — 32V
  4. External supply (+) 21.5 — 38V
  5. External supply (+) 21.5 — 38V
  6. Battery charger (+)
  7. Over-temperature protection
  8. GND
  9. Charge (+) 21.5 — 32V
  10. Battery charger (+)
Technical Specifications
  • Frequency
    1.5 - 30 MHz in 100Hz steps
  • OutPut
    2W or 20W PEP
  • ATU
    Built-in Antenna Tuning Unit ASG-6861
  • Modulation
    J3E (SSB) in LSB or USB, A1A (CW) and (optionally) FSK
  • Channels
    4 + 1
  • IF1
    40.090 MHz
  • IF2
    9.910 MHz
  • Power
    19 - 38V DC
  • Battery
    30V, 1/8 Ah
  • Temperature
    -35°C to +55°C
  • Dimensions
    315 x 300 x 92 mm
  • Weight
    8.5 kg (including battery)
Options
  • LG-6874/1
    Battery charger
  • LG-6864/11
    Battery charger
  • KG-6864/1
    Hand generator
  • BT-6861/11
    Battery NiCd 30V, 1.8 Ah (rechargeable)
  • BT-6861/21
    Battery NiCd 30V, 4 Ah (rechargeable)
  • BT-6861/31
    Battery Li/Mn 39.2V, 10 Ah (non-chargeable)
  • FH-6864
    Vehicle mount
  • FH-6865/24
    Vehicle Mount 24V
  • LA-6861
    Long-wire antenna
  • A-6864
    Vertical 3.3 metre rod antenna (whip, multi-section, foldable)
  • SV-6863
    100 W Transmitter Amplifier
  • BG-6861/1
    Remote control unit
Documentation
  1. 20W HF Manpack Transceiver SE-6861/12 mod, Operating Instructions
    AEG Telefunken. Date unknown.

  2. Brochure, Funkschreib-Einrichtung FFT-6856 / SE-6863
    Feldfunkgerät SE 6861 Datenblatt. Funkschreib-Terminal FFT 6856.
    N 116.106.0. AEG Telefunken. Ulm (Germany).

  3. SE-6861 Technical Manual 1
    5X.0172.232.78. Telefunken System Technik (TST), 1978, issue 1012.
  1. Document obtained via RadioAmateur.EU website.

References
  1. Anonymous source, Images of Dutch Special Forces using MEROD
    Photographs reproduced here with permission from the owner. March 2012.

  2. Rüdiger Stingel (DL1ITU), AEG SE6861 Battery replacement (self-construction)
    Retrieved October 2019.

  3. Peter Linschmann, Neuentwicklung AKKU für SE6861/12
    Retrieved October 2019.
Further information
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Crypto Museum. Created: Friday 27 January 2012. Last changed: Friday, 04 October 2019 - 13:03 CET.
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