Click for homepage
TSCM
NLJD
USSR
Stasi
  
Orchidea-3
Non-linear junction detector · NLJD

Orchidea-3 (Russian: ОРХИДЕЯ-3) 1 is a non-linear junction detector, or NLJD, developed in the mid-1980s in the former Soviet Union (USSR) and used during the Cold War as a countermeasures device by the countries of the former Warsaw Pact for finding covert listening devices (bugs). Due to the NLJD operating principle, the device can find both active and inactive electronic devices. It was used by Soviet intelligence services like the KGB and sister organisations like the MfS (Stasi).

The device consists of three functional blocks: a power supply unit (PSU), a transceiver (TRX) and an antenna. Together with cables and other parts it was usually supplied in an aluminium suitcase.

It has a pulse transmitter, much like radar, that creates 1.2µs pulses on a frequency 2 near 875 MHz, with a repetition rate of 500 Hz or 20 kHz. In contrast to most competitive NLJDs, it has a high power output, of 10-35 Watts, or even 350 Watts 3 . The image on the right shows a typical Orchidea-3 set that was used for many years by the secret security service of the DDR, the Stasi.
  
Orchidea-3 main unit with antenna

The device works by the virtue of the fact that semi-conducting materials — in particular the P-N junctions found in diodes, transistors and ICs — have non-linear properties. When such an object is illuminated by a particular frequency (f1), these properties cause harmonic frequencies of the illumination frequency to be generated, in particular the 2nd harmonic (f2) and the third one (f3). This effect is present in any P-N junction, regardless of whether the device is powered or not.

Note that other materials, such as rusty nails and oxidised pieces of metal, may cause a false positive. The receiver inside Orchidea-3 is suitable for detection of the second harmonic (f2) only, which is usually the strongest. Modern NLJDs are often capable of checking the ratio between the 2nd and the 3rd harmonic, in order to discriminate an electronic circuit from, say, a rusty nail.

  1. ОРХИДЕЯ (Ochidea) is the Russian word for orchid.
    It starts with the letter 'O' which is common for Russian countermeasures equipment of the era.
  2. According to sources on the internet [3], the microwave module inside the transmitter is suitable for 500 to 570 MHz, but this appears to be incorrect. The transmitter of the device featured here, produces a 20 MHz wide signal with its centre at 870 MHz. This corresponds to the manual, which states 875 MHz ± 5 MHz [A].
  3. 350W output is only possible with a repetition rate of 500 Hz.

Complete Orchidea-3 kit Orchidea-3 set Orchidea-3 main unit with antenna Main unit with carrying strap Orchidea-3 main unit - transmitter side Antenna connected to main unit Power supply unit (PSU)
A
×
A
1 / 7
Complete Orchidea-3 kit
A
2 / 7
Orchidea-3 set
A
3 / 7
Orchidea-3 main unit with antenna
A
4 / 7
Main unit with carrying strap
A
5 / 7
Orchidea-3 main unit - transmitter side
A
6 / 7
Antenna connected to main unit
A
7 / 7
Power supply unit (PSU)

Setup
Orchida-3 consists of three functional blocks:

  1. IP
    Power inverter
  2. PRP
    Transceiver → transmitter (P) and receiver (PR)
  3. K
    Antenna
The diagram below shows how the 3 units are connected. At the centre is the Transceiver (PRP) which consists of a powerful 875 MHz impulse transmitter (P) 1 and a receiver (PR) 2 that listens to its harmonic frequencies. It is powered by 220V AC supplied from the mains, or by a 12V DC battery, via a 10 metre long extension cable from the Power Inverter (IP) 3 at the left. The actual transceiver (PRP) is connected to the Antenna (K) 4 by means of two high-quality coaxial cables.


At the right is the object under test, which can be a piece of furniture, a plastered wall, a wooden construction or a special test device, known as the imitator, that behaves like a typical electronic circuit. The imitator consists of two metal rods connected at the centre by a non-linear device (a special detector diode). It can be used for testing the device and for training personnel. With a properly functioning Orchidea-3, the imitator should be 'visible' from a distance of 10 metres.

  1. P = Peredatchik (Russian: Передатчик) which means transmitter.
  2. PR = Priyemnik (Russian: Приемник) which means receiver.
  3. IP = Invertirovaniye Pitania (Russian: Инвертирование Питаниая) which means inverting power supply.
  4. K = Konus (Russian: Конус) which means cone.

Features
The diagram below gives an overview of the controls and connections on the body of the main unit: the transmitter-receiver (transceiver). At the left (hidden from view) is a 4-pin male socket for connection to the external power supply unit (PSU), which is usually placed elsewhere in the room. At the right are two coaxial sockets (marked K1 and K2) for connection to the antenna.

Orchidea-3 main unit, seen from the transmitter side

The device has two front panels: one for the receiver and one for the transmitter, with the latter usually positioned at the top (when carrying the device by the shoulder strap). The transmitter has a large 4-position dial marked РЕЖИМ (MODE) for selection of the desired mode of operation. A similar dial is present on the front panel of the receiver. It controls an 11-position attenuator that ranges from 0dB to -50dB. Note that the headphones socket (part of the receiver) is located at the front panel of the transmitter. This was probably done for convenience, as it is at the top.

Orchidea-3 power supply unit, seen from the rear

The main unit is powered by the external power supply unit (PSU) shown in the diagram above. It is shown here from the rear, so that most connections are clearly visible. The PSU can be powered by the AC mains or by a 12V battery, all of which are connected at the rear. A voltage selector 1 on the sloped control panel is used to select the local mains voltage. Both the mains voltage and the battery voltage can be checked with the meter, even before the device is switched ON. The red alarm lamp lights up when the battery is connected the wrong way around (reversed polarity).

Orchidea-3 antenna

The third major component of the Orchidea-3 installation, is the handheld dome antenna that is connected to the main unit by means of two coaxial cables. A pistol grip can be attached at the rear for easier operation when searching a room for hidden devices. The green rear panel holds the sockets for the coaxial cables, and also acts as a reflector for the two concentric tapered wideband helical antennas that are hidden inside the glass fibre dome (or cone) at the front.

  1. WARNING — Note that the recessed contacts of the voltage selector can be touched with a finger. This is potentially lethal, as they carry the live mains voltage.

Orchidea-3 main unit - transmitter side Orchidea-3 main unit - receiver side Antenna sockets (K1 = transmitter, K2 = receiver) Power socket (for connection to the PSU) Power supply unit (PSU) Rear view Rear side Antenna with pistol grip attached at the rear
B
×
B
1 / 8
Orchidea-3 main unit - transmitter side
B
2 / 8
Orchidea-3 main unit - receiver side
B
3 / 8
Antenna sockets (K1 = transmitter, K2 = receiver)
B
4 / 8
Power socket (for connection to the PSU)
B
5 / 8
Power supply unit (PSU)
B
6 / 8
Rear view
B
7 / 8
Rear side
B
8 / 8
Antenna with pistol grip attached at the rear

Modes
The transmitter has the following modes of operation:

  • 20K
    20 kHz repetition rate, 10-35W pulse
  • 0
    Standby
  • 500 min
    500 Hz repetition rate, 10-35W pulse
  • 500 max
    500 Hz repetetion rate, 350W pulse
Orchidea-3 in use
Herbert Kunz · personal account

Security services are generally not very open about their work and their methods. It will therefore not be a surprise that there are virtually no surviving stories about how the Soviets searched their embassies, residencies and apartments, an how — if any — bugs were detected and discovered.

Luckily, this situation was different in the former DDR (East-Germany). Following WWII, the DDR was established as a communist state in 1949, administered 1 by the Soviet Union (Russia). After the fall of the Berlin Wall in 1989, the DDR was reunited with West-Germany (BRD) in 1990, the East-Germans became West-German citizens, and the Stasi-archives fell into Western hands.

The use of Orchidea-3 and other Eastern countermeasures equipment, is well-illustrated by the stories of former countermeasures technician Herbert Kunz, some of which were published in the magazine Der Detektiv over the course of 2012 and 2013. Following a number of spy incidents in foreign DDR representations 2 , Kunz had been employed from 1974 onwards as a technician at Abteilung Schutz (protection department) of the East-German Außenministerium (Foreign Office).

In 1975, the DDR was recognised by the United Nations as an official nation state, after which embassies, residencies and homes were established in more than 100 countries. Needless to say that it was of the utmost importance to the DDR Goverment that these objects were free of covert listening devices (bugs). During his time at the DDR Foreign Office, Kunz found numerous bugs, mainly by means of visual inspection and with help of simple tools like field-strength indicators.

All that changed when the Orchidea-3 NLJD was introduced in the mid-1980s. Many objects were searched again, and a wide variety of bugs were discovered by Kunz, most of which were though to have been planted by Western adversaries, like the British MI6 and the United States CIA.

The image on the right shows two of the items that were found in 1987 in London, in the 12 cm hollow space between the DDR Embassy and its next door neighbour. At the time it was believed that the items were planted by the British secret intelligence service MI6 via the adjacent building.
  
SWM-44B microphone (left) and SRN-58 antenna (right)

The large item at the top is an SRN-58 antenna for 1500 MHz, developed in 1969 by the Dutch Radar Laboratory (NRP), exclusively for the US Central Intelligence Agency (CIA). The smaller item is an SWM-44 microphone developed in 1986 by the US microphone manufacturer Knowles, also exclusively for the CIA. It seems therefore more likely that the bugs had been planted by the CIA.

After the fall of the Berlin Wall in 1989 and the subsequent reunification of the two Germanies in 1990, Kunz stayed in the bug-finding trade and made a living as a security advisor/engineer and teacher. He used the Orchidea-3 for many years after the end of the Cold War, as it was able to discover bugs far more easily than its Western counterparts, such as the Scanlock Broom and the REI Eagle, not least because of the much higher RF power level 3 of the illumination signal [2].

Western bugs found in DDR objects
Below is a non-exhaustive overview of the bugs that were discovered by Herbert Kunz and his colleagues, with help of the Orchidea-3 non-linear junction detector (NLJD) featured here:

  • 1986
    Five remote controlled bugs in the DDR residency in Harare (Zimbabwe)
  • 1987
    Several Bugs in the new DDR embassy in London 4
  • 1987
    Operational bug in a DDR embassy personnel apartment in Cairo (Egypt)
  • 1987
    Defective bug in another apartment in Cairo (Egypt)
  • 1987
    Various bugs in the DDR representation in Bonn (West Germany)
  1. Except for West-Berlin, which was controlled by West Germany (BRD).
  2. For example: in 1973, telephone bugs had been found in the DDR representation in London (UK), as well as manipulated mains wall sockets in Düsseldorf (West-Germany).
  3. The Orchidea produces a 30 W (optionally 350 W) pulsed signal, whereas the Scanlock Broom produces a 60 - 600 mW continuous signal.
  4. At the time, these bugs were attributed to the British MI6, but in retrospect — based on items in the collection of Crypto Museum — it seems more likely that the bugs were placed by the American CIA.



An overview of all Orchidea-3 related items that are present in the suitcase

Parts
Metal storage and transport case Pulse transmitter and receiver (TRX) or (PRP) Cone-shaped transmit and receiver antenna (K) Power Supply Unit (PSU) or Power Inverter (IP)
PSU
Engonomically shaped grip for holding the antenna Tripod for placing the antenna in a permanent position Two coaxial cable for connection between the main unit (PRP) and the antenna (K) Mains power cable
Power cable between power supply (IP) and main unit (PRP) Battery cables Device for simulating a non-linear junction Spare parts Headphones Speaker Shoulder strap Technical and Operating Manual
Storage case
The large green aluminium suitcase shown in the image on the right, was supplied for storage and transport of the Orchidea-3 set. It has a custom-made foam-padded felt interior, with cut-outs for the three major parts and their accessories.

Although the suitcase provides proper protection of its contents, it can be recognised from a mile away. When an observation team spotted this case being carried into an embassy, they knew that the rooms were going to be swept for bugs.

  
Aluminium storage and transport case

Transceiver (main unit)   PRP
The main unit is the actual non-linear junction detector (NLJD). It consists of a pulse transmitter and an harmonics receiver, fitted in a single case that can be carried at the operator's shoulder.

It is powered by 220V/400 Hz provided by the external power supply unit (PSU) via a 10 metre cable, and is connected to the portable antenna by means of two high-quality coaxial cables.

 Look inside the main unit

  
Orchidea-3 main unit - transmitter side

Antenna   K
The devices comes with a special antenna that consists of two spiral cone antennas on a single axis: one for the transmitter at the illumination frequency (f1) and one for the receiver at the double frequency (f2). The two antennas are protected against damage by a glass fibre cone. The green metal rear panel acts as a reflector.

The antennas have circular polarisation and an 80 degree opening angle. The rear panel holds two coaxial sockets, K1 and K2, for connection to transmitter and receiver. A pistol grip can be fitted to allow it to be pointed in any direction.

 Look inside the antenna

  
Dome antenna with double helical

Power supply unit   IP
The main unit is powered by a 220V/400 Hz voltage, provided by the external power supply unit (PSU) shown in the image on the right. In Russian, the PSU is known as Инвертирование Питаниая (Invertirovaniye Pitania, or IP), which means inverting power supply.

At the rear are the connections for the AC mains and for an external 12V battery. The socket for connection to the main unit is at the front. The sloped top panel holds the ON/OFF switch, the mains voltage selector, and a voltage meter.

 Look inside the PSU

  
Power supply unit (PSU)

Antenna grip
The pistol grip shown in the image on the right, can be fitted to the rear of the antenna (K), allowing it to be pointed more easily in the direction of the object under test.

The grip has a bajonet fitting at the front that mates with the stub at the centre of the rear panel of the antenna. It has a threaded ring at the bottom, allowing it to be fitted on a tripod.

  
Pistol grip for antenna

Tripod
A tripod was supplied for putting the antenna in a fixed position, for example when examining multiple objects, by placing them one-by-one in front of the antenna.

The pistol grip has a treaded hole at the bottom, which fits a regular photographic tripod, such as the one shown in the image on the right.

  
Tripod

Coaxial cables
Two high-quality coaxial cables are supplied for connecting the antenna (K) to the main unit (PRP). One cable connects the K1 socket of the transmitter to the K1 socket of the antenna, whilst the other one connects the K2 socket of the receiver to the K2 socket of the antenna.

The cables are approx. 2 metres long each, but longer cables can be used if necessary, as long as they both have the same length.

  
Two coaxial cables for connection of the antenna(s)

Mains cable
The external power supply unit (PSU or IP) is the only device that should be connected directly to the AC mains, for which the cable shown in the image on the right should be used.

One end of this cable has a typical 4-pin female plug – connected to the 4-pin male socket at the rear of the PSU – whilst the other end holds a power plug that fits a local mains wall socket.

  
Mains power cord

Power cable
When searching a room for bugs, the main unit was usually carried on the shoulder, using the leather strap, whilst the power supply unit (PSU) was placed at a fixed position, usually near a mains wall socket. The PSU is connected to the main unit, by means of the 10 metre shielded power cable shown in the image on the right.

The cable has a 4-pin male plug at one end, and a 4-pin female plug at the other. Note that this cable carries a 220V/400 Hz voltage, which is potentially lethal. The brown bakelite reel is an aftermarket addition.

  
Power cable on reel

Battery cables
When using Orchidea-3 in an environment where no mains voltage is available, or in situations were bugs are expected on the mains power lines, it is possible to run the device from a 12V DC source, such as the battery of a car.

In that case, the large clips of the cable shown in the image on the right (or a variant), should be fitted to the (+) and (-) poles of the battery, whilst the other end of the cable is fitted to the banana sockets at the rear of the PSU. The slide switch on the PSU should be set to АККУМ.

  
Cable for connection of car battery

Imitator
In order to get acquainted to the Orchidea-3, and for checking its operation, the imitator shown in the image on the right is supplied. It consists of a two metal pins – acting as antennas – with a radar diode at the centre. As the diode consists of a P-N barrier, it has non-linear properties that can be detected by the device.

With Orchidea-3 set to its highest power output of 350 Watts at 500 Hz — MODE selector at 500 max — it should be possible to discover the imitator from a distance of 10 metres [A].

  
Imitator

Spare parts   ZIP
Each Orchidea-3 set comes with a cylindrical black plastic container that contains spare parts, like fuses, radar diodes (used in the imitator), screws, pins for the mains power plug, etc.

In Russian, this container is known as Запасные части И Принадлежности or ЗИП (Latin: ZIP), which means: Spare Parts and Accessories.
  
Spare parts in front of plastic ZIP container

Headphones
Initially, Orchidea-3 was supplied with a stethoscope-style earpiece, but this was later replaced by the Russian military-grade pair of headphones shown in the image on the right.

The headphones should be connected to the two-pin socket on top of the device (i.e. on the front panel of the transmitter). It is used for reproducing the audio tone generated by the echo (i.e. the f2 harmonic frequency) of the pulsed f1 illumination signal.

  
Headphones

Speaker
Instead of using the headphones shown above, it was also possible to use the bare speaker shown in the image on the right. This is basically one half of a pair of headphones, connected to a short cable with a 2-pin plug at the end.

This speaker is particularly useful for exercises and demonstrations, as the echo tone can be heard by multiple people. It is not recommended for finding bugs in a real-life situation, as the sound from the speaker can also be heared by a potential eavesdropper, providing an indication that the room is being swept for bugs.

  
Small speaker

Shoulder strap
The leather carrying strap shown in the image on the right, can be attached to the stubs at the side of the main unit, allowing the main unit to be carried on the shoulder, with the transmitter's front panel facing upwards, and the front panel of the receiver at the bottom.

It allows the main unit to be carried through the room under test, with the main unit connected to the power supply unit via a 10 metre cable.
  
Leather carrying strap

Manual
Each Orchidea-3 came with an original technical manual in Russian – with operating instruction and a full technical description – complete with the circuit diagrams. In the DDR (East-Germany) the manual was translated into German. 1

Bad quality copies of the German manual and the original Russian circuit diagrams 2 are available for download below. Crypto Museum are still looking for an original Orchidea-3 manual.

 Download the German manual
 Download the Russian circuit diagrams

  

  1. The translation is not of the highest standard and contains quite a few mistakes and translation errors.
  2. Better quality circuit diagrams – made by ourselves – are available below.

Double helical antenna with dome removed Antenna with pistol grip attached at the rear Holding the antenna by the pistol grip Antenna connected to main unit Antenna on tripod Tripod and pistol grip Open ZIP container with spare parts Spare parts in front of plastic ZIP container
Power cable on reel Real with power cable Winding up the cable reel Power cable on reel Cable for connection of car battery Cable for connection of 12V DC source Green hamerite aluminium storage case for Orchidea-3 Storage case interior
C
×
C
1 / 16
Double helical antenna with dome removed
C
2 / 16
Antenna with pistol grip attached at the rear
C
3 / 16
Holding the antenna by the pistol grip
C
4 / 16
Antenna connected to main unit
C
5 / 16
Antenna on tripod
C
6 / 16
Tripod and pistol grip
C
7 / 16
Open ZIP container with spare parts
C
8 / 16
Spare parts in front of plastic ZIP container
C
9 / 16
Power cable on reel
C
10 / 16
Real with power cable
C
11 / 16
Winding up the cable reel
C
12 / 16
Power cable on reel
C
13 / 16
Cable for connection of car battery
C
14 / 16
Cable for connection of 12V DC source
C
15 / 16
Green hamerite aluminium storage case for Orchidea-3
C
16 / 16
Storage case interior




Click to see more

Interior
Main unit   PRP
The device is housed in a strong machined aluminium enclosure, of which the inside is silver-plated. It is soldered at the corners and the seams, for proper RF shielding. The case has two compartments: one for the transmitter and one for the receiver, that are completely separated.

The transmitter and receiver are each built on a strong machined aluminium plate that also acts as the front panel. The transmitter is installed in the upper compartment, whilst the smaller but more complex receiver is located at the bottom.

The modules are held in place by no less than 12 screws each, with a metal gasket fitted between the panel and the outer case, in order to provide sufficient RF shielding. Two of the screws are recessed and are secured with a green wax seal to prove that the case has never been opened for repair, and that it hasn't been tampered with.
  
Transmitter removed from the enclosure

The image above shows the transmitter section removed from the enclosure of the main unit. Although the transmitter is the simplest circuit, it occupies the most space, mainly because of the large valve-based microwave module and the fact that it holds the internal power supply unit.

The complete transmitter is visible at the top of this section. At its heart is the large green 1ГИ01 valve-based (tube) pulse transmitter shown in the image on the right. At the left are the wire terminals for the filament and cathode, whilst the HT voltage is fed to the anode at the right.

The 1ГИ01 is a complete RF microwave module that has a direct antenna output – here visible at the bottom – that is connected to the antenna socket via a long coaxial filter, here visible at the bottom right. This coaxial filter suppresses the unwanted second harmonic by at least 100dB.
  
Microwave pulse transmitter valve

The microwave module is anode-modulated with short 1.2µs pulses, delivered by a toriod pulse transformer, which is driven by a transistor-based pulse generator with a repetition frequency of 500 Hz or 20 kHz. Depending on the anode voltage and the duration of the pulse — selected with the MODE dial — the transmitter can deliver a peak-power level of either 10-35 or 350 Watts.

Click to see more

The receiver is about 1/3rd of the size of the transmitter, but is far more complex. It is fully transistor-based and consists of seven sub-circuits, most of which are housed in individual metal enclosures, connected via high-quality coaxial wires. It is powered by +20V from the transmitter.

The receiver is located at the bottom of the case (i.e. opposite the transmitter) with its base plate acting as the front panel. Like the transmitter, the receiver is held in place by 12 screws, two of which are secured by means of a green wax seal.

The image on the right shows the receiver panel extracted from the main unit, with a white teflon coaxial cable connected to the coaxial band filter which is permanently fitted inside the enclosure. This filter is adjusted for the double frequency (f2) and suppresses the illumination frequency from the transmitter (f1) by no less than 120dB.
  
Receiver outside the enclosure - note the coaxial filter inside the enlosure

The remaining sub-circuit are all mounted to the base plate, as shown at the top of this section. At the right is a PCB with a small power circuit, that converts the +20V from the transmitter into suitable voltages for the individual modules. The flat device (here marked '00') is the RF mixer.

It combines the input signal from the antenna (f2) with the signal from a local oscillator that is adjusted 100 MHz above the reception frequency (f2) to deliver an 100 MHz IF signal. The image on the right shows the free-running oscillator, which is built around two 1T387A RF transistors with their tuned circuits in stripline technology.

The output from the mixer is first amplified in a 2-stage IF pre-amplifier, before it is fed to a 11-step attenuator that is fitted at the far end of the base plate. It consists of a resistor network that is soldered to the pins of a large rotary switch.
  
Local oscillator - interior

The attenuator is the only part of the receiver that is not shielded individually. Next, the signal at the output of the attenuator is boosted in a 4-stage power amplifier which also holds the diode detector. It reduces the bandwidth of the IF signal by means of tuned circuits between the stages. The video signal at the output of the booster is then passed to the last receiver module, which consists of a video amplifier, a pulse shaper and an audio amplifier that drives the headphones.

Transmitter side (Block P) Receiver side (Block PR) Recessed screw with green wax seal Transmitter removed from the enclosure Receiver outside the enclosure - note the coaxial filter inside the enlosure Receiver 4-pin socket for connection of the receiver 8-pin socket for connection of the transmitter
Transmitter Microwave pulse transmitter valve Pulse oscillator and amplifier Purpose-made transformer in the pulse oscillator circuit Coaxial filter, pulse driver transistor (black) and rectifier bridge (orange) Oscillator, pulse transformer and AF output Transmitter - MODE selector Directional coupler and power circuit
Coaxial filter fitted inside the receiver compartment Power circuit Directional coupler (part of mixer) Local oscillator Local oscillator - interior Local oscillator PCB Attenuator Receiver - shielded cable detail
D
×
D
1 / 24
Transmitter side (Block P)
D
2 / 24
Receiver side (Block PR)
D
3 / 24
Recessed screw with green wax seal
D
4 / 24
Transmitter removed from the enclosure
D
5 / 24
Receiver outside the enclosure - note the coaxial filter inside the enlosure
D
6 / 24
Receiver
D
7 / 24
4-pin socket for connection of the receiver
D
8 / 24
8-pin socket for connection of the transmitter
D
9 / 24
Transmitter
D
10 / 24
Microwave pulse transmitter valve
D
11 / 24
Pulse oscillator and amplifier
D
12 / 24
Purpose-made transformer in the pulse oscillator circuit
D
13 / 24
Coaxial filter, pulse driver transistor (black) and rectifier bridge (orange)
D
14 / 24
Oscillator, pulse transformer and AF output
D
15 / 24
Transmitter - MODE selector
D
16 / 24
Directional coupler and power circuit
D
17 / 24
Coaxial filter fitted inside the receiver compartment
D
18 / 24
Power circuit
D
19 / 24
Directional coupler (part of mixer)
D
20 / 24
Local oscillator
D
21 / 24
Local oscillator - interior
D
22 / 24
Local oscillator PCB
D
23 / 24
Attenuator
D
24 / 24
Receiver - shielded cable detail

Click to see more

Antenna   K
The antenna consists of a metal back panel that acts as a reflector. It holds two coaxial sockets – one for the transmitter and one for the receiver – and a fitting for the pistol grip. At the other side is a glass fibre dome that protects the internal antennas. It is held in place by 6 recessed screws.

After removing the screws, the protective dome can be removed and the antennas are exposed, as shown in the image on the right. Inside the dome are two tapered helical (helix) antennas, spirally-wound onto a hard polystyrene foam body. Both antennas are used in axial mode, which means that their sensitive direction is perpendicular to the reflecting metal back panel.

The outer antenna is used for the transmitter. It is the longest of the two, and is adjusted for the f1 illumination frequency. At the centre of the transmission antenna is the reception antenna.
  
Two concentric tapered axial mode helical antennas

It is shorter – about half the length of the transmission antenna – as it is adjusted to the double frequency f2; the second harmonic of the illumination frequency. The image above clearly shows the two concentric polystyrene constructions, with the transmission antenna visible as a silver-plated copper wire, guided around the circumference of the outer cone, from the connector to the open end at the top. Towards the top of the transmission antenna, is a 150Ω series resistor.

Coax sockets and fitting for pistol grip Antenna dome Antenna with dome removed Antenna interior Two concentric tapered axial mode helical antennas Two concentric tapered axial mode helical antennas 150 ohm resistor Close-up of the feedpoint of the transmission antenna
E
×
E
1 / 8
Coax sockets and fitting for pistol grip
E
2 / 8
Antenna dome
E
3 / 8
Antenna with dome removed
E
4 / 8
Antenna interior
E
5 / 8
Two concentric tapered axial mode helical antennas
E
6 / 8
Two concentric tapered axial mode helical antennas
E
7 / 8
150 ohm resistor
E
8 / 8
Close-up of the feedpoint of the transmission antenna

Click to see more

Power supply unit   IP
Due to its weight, the power supply unit (PSU) is housed in a separate enclosure with two heavy black heatsinks at the sides and a sloped control panel on top. The latter is part of the U-shaped top cover (painted in hamerite green) that is held in place by 14 recessed screws; 7 at either side.

After removing the 14 recessed screws, the top panel can be lifted off — as shown in the image above — and the interior is exposed. Inside the PSU is a large toroidal mains transformer that converts the 110 or 220V AC mains into 12V AC, which is then rectified in a diode bridge and stabilised by two 4000µF electrolytic capacitors.

The resulting 12V DC drives a power inverter that produces 220V AC at a frequency of 400 Hz, delivered by a small toroidal transformer. Instead of the mains, the inverter can also be powered by an external 12V DC battery source.
  
PSU circuit board

The image above shows the printed circuit board (PCB) inside the PSU. It holds a toroid-based 400 Hz oscillator, plus a booster which produces enough energy to power the main unit (i.e. the transmitter and the receiver). The reason for using 400 Hz (rather than 50 or 60 Hz) is that it allows the use of smaller power transformers, which reduces the overall weight of the main unit.

PSU with cover removed PSU interior Input and output transformer PSU circuit board Capacitors PSU interior PSU circuit Output transformer
F
×
F
1 / 8
PSU with cover removed
F
2 / 8
PSU interior
F
3 / 8
Input and output transformer
F
4 / 8
PSU circuit board
F
5 / 8
Capacitors
F
6 / 8
PSU interior
F
7 / 8
PSU circuit
F
8 / 8
Output transformer

Circuit diagram
Transmitter
Below is the circuit diagram of the pulse transmitter. Although this circuit occupies approximately 2/3rd of the main unit, it is the simplest circuit. At the top left is the transformer, which converts the 220V 400 Hz voltage – supplied by the external power inverter – into the LT voltages (6.3V AC and 20V DC) plus the HT voltage that is supplied to the anode of the 1ГИ01/01-1 valve-based 875 MHz (adjustable) microwave module, located at the bottom right. It is heated by 6.3V AC.

Orchidea-3 transmitter

The +20V DC rail is used to power the receiver (see below). It also drives a transistor-based oscillator, which in turn drives the pulse transforer (TR3) in the anode circuit of the microwave module. The output is available directly from the microwave module, and should be connected to antenna K1. The 8-pin plug at the top left, mates with an 8-pin socket inside the enclosure. Note that the speaker socket – visible at the top right – is located 1 on the chassis of the transmitter.

Also note that the output of the 1ГИ01 microwave module is passed through a coaxial filter before it becomes available at the output socket on the side of the main unit. This rigid filter is connected directly to the output of the 1ГИ01 and is not shown in the circuit diagram above. It suppresses the harmonic frequencies produced by the transmitter with no less than 100dB.

  1. It is likely that the speaker socket was placed at the front panel of the transmitter for convenience only, as it is at the top side of the main unit, when the latter is carried by the shoulder strap.

Receiver
The receiver is the smallest, but also the most complex part of the device. It occupies about 1/3rd of the main unit, and consists of 7 sub-circuits, which are shown in the block diagram below. The active units are powered from the +20V DC rail, which is provided by the transmitter. The receiver is configured for the reception of the harmonic frequency f2 — which is twice the f1 frequency of the transmitter — that will be caused by the non-linear properties of a hidden bug.

Orchidea-3 receiver - block diagram

Each sub-circuit is housed in an individual metal enclosure, with the exception of the 11-step attenuator and the parts of the power supply, visible at the bottom right of the diagram above. The signal from the antenna is first filtered in a coaxial filter which is fitted inside the enclosure. This filter supresses the strong direct f1 signal from the transmitter with no less than 120dB.

Mixer, consisting of directional coupler and signal diode

From the filter, the signal is fed to the mixer shown above, where it is combined with the signal from the local oscillator – shown below – that oscillates at a frequency which is 100 MHz higher than the expected f2 frequency. The mixer consists of a directional coupler and a signal diode. It produces a 100 MHz signal at its output port, which is fed to the IF pre-amplifier (see below).

Local oscillator at f2 + 100 MHz

The local oscillator is built around two 1T387A transistors in grounded collector configuration, with the tuned circuit (L3 and C 1p5) connected between the bases of the two transistors. The circuit oscillates by the virtue of the parasitic capacity between the base and the emitter of each transistor. The output of the oscillator is taken from a tap of stripline L3 in the tuned circuit.

2-Stage IF pre-amplifier

The output from the mixer is first amplified in the circuit above, which is a two-stage amplifier built around two low-noise 1T329A transistors. The first transistor is used in grounded emitter configuration, whilst the second one has a grounded base. The amplifier is tuned to 50 MHz (via L3/L4), which is the center frequency of the 100 MHz wide signal from the mixer. The component values are selected such that the total bandwidth of the signal at the output port is reduced.

11-step attentuator

The output from the IF pre-amplifier is passed to the 11-step attenuator shown above. Unlike the other sub-circuits, the attenuator is not housed in a separate metal enclosure, but consists of a resistor network that is soldered directly to a 11-position rotary switch on the chassis of the receiver. It can be controlled by the user with a 11-position dial on the receiver's front panel.

4-Stage IF power amplifier and detector

The signal from the output of the attenuator is fed to the input of the 4-stage power amplifier shown in the circuit diagram above. This circuit is very similar to that of the IF pre-amplifier, but is built around 2T316B transistors (Russian: 2Т316Б). At the right is the 2A201A detector diode.

Video amplifier, pulse shaper and audio amplifier

The signal from the detector is fed to the input of the final sub-circuit, which is shown in the image above. It consists a three-stage video amplifier (T1, T2, T3), a pulse shaper (D1, D2), an AF amplifer (T4) and finally an emitter follower (T5) that directly drives the headphones. Note that the speaker is AC-coupled by means of a capacitor that is fitted outside the circuit's enclosure.

Wiring
The diagram below shows the internal wiring of the main unit. The device has two compartments: a large one and a small one, for the transmitter and receiver respectively. It also has a shielded socket for the connection to the PSU. The transmitter has an 8-pin socket that mates with the 8-pin plug shown below. The receiver has a 4-pin socket that mates with the 4-pin plug below.

Internal wiring

Large filters are present to block any RF energy from the power lines and from the lines between the two compartments. An extra capacitor is present on the +20V line. Note that the receiver is powered by the transmitter (+20V) and that for no apparent reason, the audio from the receiver is fed back to the transmitter compartment, where it is connected to the filtered speaker socket.

Power supply unit
Below is the circuit diagram of the external power supply. At the top left are the inputs from the 110 or 220V AC mains (50 or 60 Hz) and the 12V DC battery. A voltage selector (S2) is used for matching the local mains AC voltage, which is converted to 12V by transformer TR1 and a diode bridge rectifier (D1). The 12V DC voltage from the battery is connected in parallel to the output of D1, protected against reverse polarity by diode D3. A voltage meter is present at the top right, to check the input voltage (mains or battery) prior to switching the device on with power switch S1.

External power supply unit

The lower half of the diagram shows the actual power inverter, which comprises an oscillator — built around transformer TR2 — and a booster stage built around TR3. At the output of TR3, a fixed 220V voltage with an alternating frequency of 400 Hz is present. This voltage should be supplied directly to the main unit. The reason for using 400 Hz (rather than 50 or 60 Hz) is that it allows the output transformer (TR3) and the input transformer of the main unit to be smaller.


Restoratation
When we received our Orchidea-3 in October 2018, it was in well-preserved condition, but it was evident that it had seen quite some action over the years. It had been travelling all over the world during the Cold War – for finding bugs in DDR objects – and was used for many years thereafter.

The front panels of the transmitter and receiver of the main unit had several dents and scratches — all caused by regular use — and the power supply unit had lost much of its green hamerite paint, as can be seen in the image on the right.

None of the damages were serious and could be fixed easily. The cover of the PSU and the front panels of the main unit were straightened, and the paint was restored where necessary. Several connectors were refitted to their cables as they had come off over time. The capacitors were all checked and were found to be in good condition.
  
Damages at the front

Now it was time to bring it back to life again. The MODE selector was set to 500 min, which means an output power level of 30W and a repetition rate of 500 Hz. The PSU and the antennas were connected to the main unit, and the mains voltage was applied to the PSU. After setting the power switch to ON, the internal 400 Hz power inverter could be heard. After approx. 20 seconds — the valve needs to heat up first — an RF signal with the following wide spectrum was emitted:


Due to the pulsed nature of the RF signal, many sidebands are generated, resulting in a 20 MHz wide signal, with the centre frequency at 870 MHz. This corresponds to the frequency specified in the manual (875 MHz ± 5 MHz). The vertical lines in the spectrum diagram represent the 500 Hz repetition rate. As both the 875 MHz module and the 500 Hz pulse generator are free-running, the vertical lines will be moving through the spectrum continuously (i.e. there is no correlation).

The first test were carried out with the imitator on the floor of our workshop. It was detected immediately and it became evident that the antenna has quite a wide viewing angle (approx. 80 degrees). The imitator could be 'seen' from several metres away without any difficulties.

Next, we tried the device with several regular components like diodes and transistors, with varying success. Simple small signal diodes were easily spotted, but a transistor was more difficult to find, especially when its legs were in parallel. Bending the legs outwards gave better results.
  
Imitator

There were also some false positives, probably caused by (rusty) iron structures in the concrete floor of our workshop. It is clear that operating an NLJD properly requires quite a bit of practice, but by adjusting the power ouput of the transmitter and the attenuator of the receiver, it should be possible to find electronic circuits. Not bad for a device that is more than 30 years old now.

Actually, there were only two real problems with the set: (1) the meter on the power supply unit was dead and (2) the foam inside the suitcase had completely disintegrated and had become a sticky mess. - to be continued...

So far, the following restorations have been carried out:

  • All parts cleaned
  • Paint on the body of the PSU restored
  • Paint on the front panels of the main unit restored
  • Mains cable 4-pin connectors refitted
  • Power cable (reel) restored and connector refitted
  • PSU tested
  • Main unit tested and approved
Connections
Mains
Although the main unit has the same 4-pin power socket as the external PSU, it should always be powered via the PSU and not directly from the mains. The reason for this is that the main unit expects a 220V AC voltage with a frequency of 400 Hz, whilst the mains is at 50 or 60 Hz. The diagram below gives the pinout of the power socket on the PSU, when looking into the socket.

  1. 220V AC
  2. not connected
  3. not connected
  4. 220V AC
The same connector (male and female) is used for connection between the PSU and the main unit. Note that this cable carries 220V at 400 Hz (not 50 or 60 Hz), which is not compatible with the regular 220V AC mains voltage. The pinout of these connectors is as follows:

  1. 220V AC
  2. not connected
  3. Ground
  4. 220V AC
1ГИ01 Microwave Module
1GI01 (Russian: 1ГИ01) is a coaxial waveguide microwave module, based on a thermionic valve (vacuum tube), designed as a self-oscillating generator with anode modulation. It is heated with a 6.3V filament and can produce pulses of up to 3 kW. The RF output is available at a coaxial screw terminal at the side of the device [3].  Datasheet

Specifications
  • Frequency
    875 MHz ± 5 MHz 1
  • Heater
    6.3V (6 — 6.6V)
  • Anode pulse
    3.5V (≤ 3.7V)
  • Gride pulse
    -250V — 0V
  • Anode current
    2.3A (≤ 2.6A)
  • Cathode current
    ≤ 5A
  • Output pulse
    ≤ 3 kW
  • Duty cycle
    ≥ 1: 600
  • Duration
    0.5 — 1.2 µs
  • VSWR
    ≤ 1.7
  • Drift
    ± 0.3 MHz
  • Shelf life
    ≤ 12 years
  • MTBF
    1000 hrs
  • Temperature
    ≤ +140°C
  • Weight
    270 grams
  1. Some websites [3] specify the frequency range as 500 - 570 MHz, but this is likely incorrect.

Specifications
General
  • Temperature
    Storage: +5°C — 30°C, transport: -50°C — +60°C
  • Humidity
    ≤ 85%
  • Weight
    13 kg
PSU
  • Mains
    90-147V, 190-252V, 50-60 Hz
  • Battery
    12V DC ± 2V
  • Output
    220V, 400 Hz
  • Dissipation
    70W
  • Current
    4A @ 12V DC
Transmitter
  • Frequency
    875 MHz ± 5%
  • Pulse
    1.2 µs
  • Repetition
    500 Hz (± 100 Hz) or 20 kHz (± 2 kHz)
  • Output
    10-35W or 350W (when MODE is set to 500 max)
  • f2 suppression
    ≥ 100dB
Receiver
  • Sensitivity
    > 10dB
  • Attenuator
    0 to -45dB
  • Dynamic range
    > 10dB
  • Output
    0.2 mW (speaker)
  • f1 suppression
    ≥ 120dB
Antennas
  • Polarisation
    circular
  • Aperture
    < 80°
  • VSWR
    < 2
  • Gain
    ≥ 8dB
Parts
According to the original Operating Instructions [A], the following items were supplied:

Documentation
  1. Orchidee-3, Technische Beschreibung und Arbeitsanleitung
    Technical Description and Operating Instructions (German).
    Date unknown. 15 pages.

  2. Orchidea-3, Circuit Diagrams
    Date unknown. 12 pages.
References
  1. Detlev Vreisleben, Orchidea-3, technical description and operating instructions
    Personal correspondence, April — October 2018.

  2. Herbert Kunz, Orchidea-3 and accessories, personal experiences
    Personal correspondence, October — November 2018.

  3. Zapadpribor, 1G01/01-1 specifications
    Website (Russian). Retrieved November 2018.

  4. Herbert Kunz, Toiletten mit Ohren and der Themse
    Der Detektiv, September 2013. Volume 5.
Further information
Any links shown in red are currently unavailable. If you like the information on this website, why not make a donation?
© Crypto Museum. Created: Saturday 27 October 2018. Last changed: Sunday, 23 August 2020 - 11:19 CET.
Click for homepage