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BN-58   FE-8
Portable solid-state short wave receiver

FE-8, also known as BN-58, is a portable solid-state short-wave receiver, developed in 1958 by Wandel & Goltermann (W&G) 1 in Reutlingen (Germany), for use by the German intelligence service Bundesnachrichtendienst (BND) and by European stay-behind organisations (SBO). Issued as part of the SP-15 as well as the SP-20 spy radio set. Also known as Empfänger SP-15 and as SP-20E.

The BN-58 is one of the first small receivers that was fully transistorised and was characterised by a very low power consumption. The double con­ver­sion superheterodyne receiver has an IF1 of 1.635 MHz and covers 2.5-24 MHz divided over two bands, selectable with a knob at the front.

The receiver features permeability tuning (coil tuning), similar to Collins receivers, that allows the scale to be virtually linear. There is a sepa­rate tuner for each of the two frequency bands. The device is powered by an internal 6V NiCd battery or by an external 6V DC power source.
  

The receiver was originally designed for use with the SP-15 spy radio set. It has a connection at the rear that can be connected in parallel to the morse key of the FS-7 transmitter, in which case the receiver provides the side-tone during transmissions. When the SP-15 was succeeded by the SP-20, around 1970, it appeared to be difficult to develop a new digital receiver that had at least the same sensitivity as the BN-58. It was therefore decided to re-use the old BN-58 as part of the new SP-20 spy radio set. This is why there are fewer surviving BN-58 units than spy radio sets.

  1. W&G was widely known for the production of high-end electronic test equipment, such as audio and HF spectrum analyzers.  More

FE-8 (BN-58) with battery and earpiece
FE-8 (BN-58) receiver with both tuning cranks folded out
Top view
Front view
Front panel
Rear panel
Battery compartment with 6V battery
Connections at the rear
A
×
A
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FE-8 (BN-58) with battery and earpiece
A
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FE-8 (BN-58) receiver with both tuning cranks folded out
A
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Top view
A
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Front view
A
5 / 8
Front panel
A
6 / 8
Rear panel
A
7 / 8
Battery compartment with 6V battery
A
8 / 8
Connections at the rear

Features
The image below provides a quick overview of the control of the FE-8 (BN-58). It is powered by an internal 6V rechargeable NiCd battery, or by an external 6V DC power source that is connected to the 2-pin LEMO socket at the rear. It is turned on by setting the band selector either to band 1 (green) or band 2 (red). Setting the band selector to the centre postion (white) turns it off again.


Antenna and ground wires are connected to the recessed banana sockets at the left side. An ear­piece or a pair of high impedance headphones (2000 Ω) is connected to the 2-pin socket at the right edge of the front panel. Depending on the selected band (1 or 2), the foldable crank at the right or left should be used respectively. A metal stub is raised from the top surface to show which band is currently selected. The leftmost stub is raised when band 2 (red) is selected.

Top view
Front panel
Crank in storage position
Crank in operational position
Battery compartment (open)
Battery compartment with 6V battery
Connections at the rear
Close-up of raised red stub (band 2)
B
×
B
1 / 8
Top view
B
2 / 8
Front panel
B
3 / 8
Crank in storage position
B
4 / 8
Crank in operational position
B
5 / 8
Battery compartment (open)
B
6 / 8
Battery compartment with 6V battery
B
7 / 8
Connections at the rear
B
8 / 8
Close-up of raised red stub (band 2)

Block diagram
Below is the block diagram of the FE-8 receiver, based on the work of Helmut (Jim) Meyer (DJ2EI) [1]. At the left are the two different tuners (one for each frequency range). The first local oscillator and mixer are inside the tuner and produce an IF1 at 1.635MHz. This signal is mixed with a 2nd IF oscillator at 1.180 MHz. It produces a 455kHz IF2 signal that is amplified and fed to a detector. The output of the detector is amplified to a suitable level for 600-4000 Ω headphones. For the reception of CW (morse), the signal of a switchable and adjustable BFO is mixed with the 455kHz signal in the 3rd IF amplifier. In the leftmost position of the BFO-knob, the BFO is turned off.

FE-8 (BN-58) block diagram

The filter between the 2nd mixer (IF2) and the IF amplifier is a mechanical Collins band-pass filter which is just 3.1 kHz wide. In the above block diagram, the two tuners are each simplified to a single block. A more detailed block diagram of a single tuner is given below.




Battery
The FE-8 can be powered by an internal 6V battery, that consists of five stacked 1.5V NiCd cells. As the original battery is no longer in production, it may be difficult to find a replacement. It should be relatively easy however to create a good alternative from existing 1.2V NiMH cells. Suitable replacement batteries are now readily available from Akkuumbau in Germany [5].

The FE-8 can also be powered from external 6V DC source that should be connected to the power socket at the rear of the device, close to the battery compartment. This sockets needs a 2-pin LEMO connector of which both pins are used for the plus connection, whilst the shield is used for the ground (negative) contact.

The image on the right shows the charger that was supplied with the FE-8. It allows the 6V battery to be charged directly from the 220V AC mains. The battery is placed inside the outer shell, which is then fitted onto the charger.
  

The complete assembly can then be inserted into a standard wall socket. Once the battery is full, it can be placed inside the battery compartment of the FE-8 again. Alternatively, the battery can be charged directly inside the FE-8 by supplying a slightly higher voltage (7.2V) to the external DC socket at the rear. The same type of 6V stacked battery is used in the calibrator (see below).

FE-8 with home-made 6V NiCd battery
Battery fitted inside the battery compartment
Removing the battery
External power lead
External power connected to the FE-8
C
×
C
1 / 8
1 / 8
C
2 / 8
2 / 8
C
3 / 8
3 / 8
C
4 / 8
FE-8 with home-made 6V NiCd battery
C
5 / 8
Battery fitted inside the battery compartment
C
6 / 8
Removing the battery
C
7 / 8
External power lead
C
8 / 8
External power connected to the FE-8

Calibrator
The BN-58 was a very sensitive receiver with a nearly linear scale, making it easy to tune it to the desired frequency. Nevertheless, it had to be calibrated from time to time. This was done by means of the external calibrator shown in the image below, which is in fact a frequency marker.

It consists of a 15 cm long metal cylinder with a 2-pin connector at the end. The connector was inserted into the antenna and ground sockets at the left front of the receiver. The calibrator is activated by pressing (and holding) the small brown push-button on top of the connector.

The calibrator is powered by an internal 6V battery that consists of five stacked 1.2 NiCd cells; the same one as is used for the FE-8 receiver itself. Batteries of this type may be hard to find, but it should be possible to create one from standard 1.2V NiCd or NiMH cells.
  

Inside the device is a so-called comb generator [4]; a device that generates multiple harmonics from a single base frequency, all of which are identical in strength. When used with a rounded base frequency (e.g. a 1 MHz crystal) it produces a reference signal (marker) at regular (1 MHz) intervals. The device is constructed in such a way that its signal is rather weak (typically -60dBm or lower), so that the sensitivy of the receiver can be checked at the same time.

The device has two internal reference crystals plus an external one that can be inserted in the crystal socket on top of the device. At the front is a three-position rotary switch with three settings, marked I, II and III. It is used to select the mode of operation:

  1. 100 kHz
    This setting produces a -80dBm marker signal at 100 kHz intervals.

  2. 1 MHz
    This settings produces a -60dBm marker signal at 1 MHz intervals.

  3. Crystal
    In this mode, the external crystal socket on top of the device is used. It can be used with any arbitrary frequency that is within the range of the receiver. We've tried, for example, a standard amateur frequency crystal of 3.575 MHz, which generates a marker at 3.575 MHz, 7.150 MHz, etc. In this mode, the signal strength depends on the crystal's activity.
FE-8 calibration device
FE-8 calibration device
Antenna connector and power switch
Battery compartment
MODE selector (I, II or III)
Looking into the battery compartment
Install the battery this way (+ on the left)
External crystal socket
Crystal fitted into the socket
Calibrator and FE-8 receiver
Calibrator connected to the FE-8
Activating the calibrator
Using the calibrator with a standard 3.575 MHz amateur frequency crystal
Verifying the 100 kHz markers on a spectrum analyser
Verifying the 1 MHz markers on a spectrum analyzer
Verifying the amateur frequency on a spectrum analyzer
D
×
D
1 / 16
FE-8 calibration device
D
2 / 16
FE-8 calibration device
D
3 / 16
Antenna connector and power switch
D
4 / 16
Battery compartment
D
5 / 16
MODE selector (I, II or III)
D
6 / 16
Looking into the battery compartment
D
7 / 16
Install the battery this way (+ on the left)
D
8 / 16
External crystal socket
D
9 / 16
Crystal fitted into the socket
D
10 / 16
Calibrator and FE-8 receiver
D
11 / 16
Calibrator connected to the FE-8
D
12 / 16
Activating the calibrator
D
13 / 16
Using the calibrator with a standard 3.575 MHz amateur frequency crystal
D
14 / 16
Verifying the 100 kHz markers on a spectrum analyser
D
15 / 16
Verifying the 1 MHz markers on a spectrum analyzer
D
16 / 16
Verifying the amateur frequency on a spectrum analyzer

Interior
The FE-8 is housed in a die-cast aluminium enclosure that measures 184 (210 when in use) × 130 × 45 mm and weights little over 1.5 kg. The interior can be accessed by removing 6 screws from the bottom, after which the sealed bottom panel can be taken off. This reveals the two permeability tuners (variometers) and additional electronic PCBs, as shown in the image below.


The receiver is not very service friendly, as most repairs require a nearly complete disassembly of the device in order to access the components on the various PCBs. To illustrate this, the image below shows a BN-58 of which Variometer 1 has been removed. Note that the oscillator and the first mixer are mounted to the variometer. The construction of Variometer 2 is nearly identical. Note that the 2nd IF stage (rear), the BFO and the AF circuits (front) are common to both bands.


FE-8 interior (bottom view)
FE-8 interior seen from the bottom of the radio
Input filter and protection
Band 1 permeability tuning (variometer 1)
Mechanical filter and 2nd IF
Band 1 oscillator and 2nd IF stage
Side-tone monitor and variometer 2 (tuning scale just visible)
Variometer 1 removed from a broken FE-8 (BN-58)
E
×
E
1 / 8
FE-8 interior (bottom view)
E
2 / 8
FE-8 interior seen from the bottom of the radio
E
3 / 8
Input filter and protection
E
4 / 8
Band 1 permeability tuning (variometer 1)
E
5 / 8
Mechanical filter and 2nd IF
E
6 / 8
Band 1 oscillator and 2nd IF stage
E
7 / 8
Side-tone monitor and variometer 2 (tuning scale just visible)
E
8 / 8
Variometer 1 removed from a broken FE-8 (BN-58)

Permeability tuning
The two tuners are highly complicated devices with multiple permeabilty tuning coils, resulting in a nearly linear tuning scale. Turning the crank moves the ferrites in and out of the coils. In order to eliminate any linearity errors, a sophisticated adjustment-correction mechanism is present, as shown in the images below. It comprises a number of tuning points and a lever that senses the correction curve formed by these tuning points. Never alter the adjustments of the tuning points.

Permeability tuning was a special feature of the BN-58 that was not commonly found in other clandestine receivers of the era, except for the contemporary RR/E-11 which has a very similar construction. Nevertheless it wasn't new, as it was already used during WWII in the American RBZ Receiver. In the 1960s, permeability tuning was also used in some early car radios.

F
×
F
1 / 3
1 / 3
F
2 / 3
2 / 3
F
3 / 3
3 / 3

Specifications
  • Device
    Portable short wave receiver
  • Purpose
    Clandestine agent-centre communications
  • Model
    BN-58
  • Designator
    FE-8
  • Year
    1958
  • Manufacturer
    Wandel & Goltermann
  • Part of
    SP-15, SP-20
  • Principle
    Double conversion superheterodyne
  • Frequency
    2.5 - 24 MHz
  • Bands
    2 (see below)
  • Modulation
    AM, CW
  • IF1
    1.635 MHz
  • IF2
    455 kHz
  • Output
    600-4000Ω (typically: 2000Ω)
  • Power
    6V DC
  • Dimensions
    184 × 130 × 45 mm (210 × 130 × 45 mm when in use)
  • Weight
    1508 g
Bands
  1. Green
    2.5 - 9.1 MHz
  2. Red
    9.1 - 24 MHz
Nomenclature
  • FE-8
  • BN-58
  • SP-20E
  • Empfänger SP-15
  • Kurbelempfänger (crank receiver)
Documentation
  1. BN-58 Receiver circuit diagram 1
    Wandel & Goltermann, 30 September 1960.
     Same diagram rotated by 90°

  2. BN-58 alignment and repair procedure (German) 2
    Wandel & Goltermann, 30 September 1960.

  3. LG-8A Battery charger, circuit diagram 1
    Wandel & Goltermann, date unknown.
  1. Document kindly provided by Jim Meyer [1]. Document kindly provided by Günter Hütter 6.

References
  1. Helmut 'Jim' Meyer, HS0ZHK, My way to Ham - Radio and beyond
    Detailed technical description of the FE-8 (BN-58) in German and English.
    Website QRZ.COM. Personal correspondence. Retrieved April 2013.

  2. Louis Meulstee, Wireless for the Warrior, volume 4
    ISBN 0952063-36-0, September 2004

  3. Wandel & Goltermann, BN-58 circuit diagram
    30 September 1960.
     Same diagram rotated by 90°

  4. Wikipedia, Comb generator
    Retrieved April 2013.

  5. Akkuumbau, FE-8 replacement battery
    Retrieved 21 August 2017. 1

  6. Günter Hütter, BN-58 alignment procedure
    Received March 2013.
  1. Website defunct since 2021. Page retrieved via WayBack Machine. Original URL:
    https://www.akkuumbau.de/ersatzakku-zum-selbsteinbau-fur-wandel-und-goltermann-fe8.html

Further information
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Crypto Museum. Created: Monday 03 August 2009. Last changed: Sunday, 09 June 2024 - 22:31 CET.
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