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Mk XV
British WWII spy radio set

Mk XV, or Mark 15, was a clandestine radio, also known as a spy radio set, developed in 1943 by Section VIII of the Secret Intelligence Service (SIS, MI6) at Whaddon Hall (UK). It was intended for use by agents and resistance groups in occupied Europe. The transmitter featured here, was used during WWII by intelligence officer Alfonso Grisoni of the French resistance group Jade-Amicol [4].

A complete radio station comprises a receiver, a transmitter, a power supply unit and (optionally) a power inverter, each of which was housed in a separate enclosure, made of wood or metal. 1

The image on the right shows the transmitter, which is housed in a plywood enclosure with a hinged lid and drilled ventilation holes 2 in the side panels. It covers a frequency range from 3.5 to 16 MHz in three bands, and produces an output power of 15 Watts. It has a fixed power cable with a 4-pin Jones plug at the end, that mates with a socket on the power supply unit.
  
Front panel

Note that the transmitter has a single antenna socket and no connection for the counterpoise. 3 The set was used by SIS agents in occupied Europe, and also by resistance groups that worked for the SIS, such as the French Jade-Amicol Network. Contrary to popular believe, it was not used by the SOE — the SOE developed its own sets from 1942 onwards — and was not developed around 1939, as suggested in [2], but in 1943. It is therefore not the first spy radio set of WWII [6][12]. Nevertheless, it is an iconic agent and resistance radio set, of which very few have survived.

The Mk XV can be seen as one of the successors of the Mk V (Paracette), and was used in areas where medium power was required (15W), such as Southern France and Norway. It was more secure than the the second version of the Mk V (Paracette) 4 – also known as the Agent Killer [6] – and the Mk VII (Paraset), both of which had a receiver that could be detected from miles away.

The Mk XV was later succeeded by the very similar Mk. 16. 5 Towards the end of the war, several Mk 16 units were supplied to a very secret Danish stay-behind organisation, that would be activated after the war in the event of a Russian invasion. However, the Mk 16 was not suitable for the Danish DC mains network and was eventually replaced by the Danish Telefonbogen [1].

  1. There are plywood boxes and steel enclosures, and even combinations of these two. The steel enclosures were made by a small local company in Whaddon village, that produced cash boxes before the war [1].
  2. The transmitter featured here has drilled ventilation holes, whereas some other surviving Mk XV units have slotted ventilation holes.
  3. The transmitter's ground is connected – via the PSU – to the receiver. The counterpoise for the transmitter's antenna is therefore shared with the counterpoise of the receiver.
  4. The first version of the Mk V had a receiver with a separate RF pre-amplifier stage (1-V-1), but that was omitted in a later version (0-V-1). The RF pre-amplifier was re-introduced in the Mk XV.
  5. Note the use of Arabic numerals (16) instead of Roman numerals (XVI).

Wooden enclosure after restoration
Mk XV transmitter with open lid
Mk XV with fully open lid
Front view
Front panel
Frequency tuning table
Original crystals
External morse key
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Wooden enclosure after restoration
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Mk XV transmitter with open lid
A
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Mk XV with fully open lid
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Front view
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Front panel
A
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Frequency tuning table
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Original crystals
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External morse key

Features
A complete Mk XV station consists of a transmitter, a receiver and a power supply unit (PSU). At present, we only have the transmitter in our collection, which is shown in the image below. In the ideal situation, it is connected to the original PSU, along with the original receiver. Separate antenna wires should be connected to transmitter and receiver, whilst a counterpoise wire is connected to the receiver only. It is shared with the transmitter through the 0V line of the PSU.

Front panel of the Mk XV transmitter. Click to zoom in.

A suitable crystal should be installed in the XTAL socket at the left, whilst the desired frequency range should be selected with the oscillator range (MEGS OSC) and PA range (MEGS PA) knobs. Next, the 12-position preselector for the desired range should be set to the number indicated in the frequency table that is fitted inside the case lid. Whilst holding down the internal morse key, the OSC TUNE knob should be adjusted for 80% of maximum light of the OSC INDICATOR. Next, the PA TUNE knob should be adjusted for a minimum reading on the PA TUNE/AE SELECT meter.

The Mk XV transmitter is now ready for use. For testing purposes, the transmitter can also be powered by the PSU of the earlier Mk VII (Paraset), as it has the same pinout of the power socket. Note however that in that case a suitable counterpoise must be connected to the PSU chassis.

Front view
Front panel
Front panel
External morse key connected
Empty crystal socket (XTAL)
Crystal installed in socket
Alternative crystal
Alternative crystal installed in socket
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Front view
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Front panel
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Front panel
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External morse key connected
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Empty crystal socket (XTAL)
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Crystal installed in socket
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Alternative crystal
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Alternative crystal installed in socket



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Parts
Transmitter
TX
Receiver
RX
Power supply unit
PSU
Power inverter
Quarz Crystals
External morse key
Antenna wire
Transmitter
The transmitter is housed in a wooden enclosure that measures 287 x 160 x 140 mm and weights 3.4 kg. It is connected to the PSU by means of a 4-pin male Jones connector.

At present, the transmitter is the only unit of the Mk XV in our collection.
  
Mk XV transmitter with open lid

Receiver   wanted
The receiver is slightly smaller than the transmitter. It is also housed in a wooden or metal enclosure and is connected to the PSU by means of a 6-pin male Jones connector.

At present, the receiver is missing from our collection.
  

Power supply unit   wanted
Depending on the version, the power supply unit (PSU) is housed in a metal or wooden enclosure that measures 300 x 160 x 140 mm and weights 6.8 kg. It has a fixed cable for connection to the mains and two sockets for connection of the transmitter and the receiver respectively.

There were three different versions of the PSU, one of which was a 6V power inverter. At present, the PSU is missing from our collection.
  

Power inverter   wanted
The Mk XV could also be powered from a 6V DC source, by using an (optional) rotating power inverter. The device is housed in a metal enclosure and features a Carter 417 XV rotary transformer.

At present, the power inverter is missing from our collection.
  

Crystals
The Mk XV transmitter is crystal driven. Without a crystal it can not be used. A suitable crystal, with two 3 mm pins spaced at 19 mm, should be installed in the socket marked XTAL.

The image on the right shows an original crystal that was found with the transmitter. It was made before and during WWII in the USA. Other crystal types are also known to have been used.

 More about crystals

  
Original crystals

External morse key
The transmitter was only suitable for continuous wave (CW) transmissions in morse code (A1A). Although the transmitter has a built-in morse key at the front right, it was also possible to connect an external one, such as the Key No. 2 shown in the image on the right.

The key should be connected to the socket marked EXT KEY at the front edge. In practice, many operators brought their own key.
  
External morse key

Antenna wire
For proper operation of the transmitter, a long wire should be used as an antenna, along with a proper counterpoise (ground). The antenna wire shown on the right, should be connected to the socket marked AE in the upper right corner.

Note that the transmitter does not have a socket for connection of the counterpoise. Instead, the counterpoise is shared (via the power cable) with the receiver's counterpoise.
  
Antenna wire with 3 mm plug

Transmitter parts
Mk XV transmitter with open lid
Original crystals
Crystal installed in socket
Alternative crystal
Alternative crystal installed in socket
External morse key with rubber cable and connector
External morse key
External morse key connected
Antenna wire with 3 mm plug
C
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C
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Transmitter parts
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Mk XV transmitter with open lid
C
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Original crystals
C
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Crystal installed in socket
C
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Alternative crystal
C
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Alternative crystal installed in socket
C
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External morse key with rubber cable and connector
C
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External morse key
C
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External morse key connected
C
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Antenna wire with 3 mm plug

History
Development
It is a common misunderstanding that the Mk XV was developed in 1938 or 1939. In reality it was released some time in 1943. The reason for this misunderstanding is most probably the limited amount of information that was available in the public domain in 1972, when Pierre Lorain wrote his excellent book Secret Warfare [2]. He had heard from former SOE members that the first radio set to be used in France was housed in a wooden enclosure, so when he found an Mk XV receiver is a museum in Paris in the late 1960s, he probably assumed that he had found the right one [6].

Unfortunately, this is an historical mistake. We now know that the Mk XV was developed in 1943. A good summary of the development of the early SIS radio sets, is given by Dave Gordon-Smith in Electric Radio Magazine of September 2018 [6]. In his article The Agent Killer, he demystifies the history of the clandestine SIS sets, based on information that has recently become available.

 Read the article


Alfonso Grisoni   27 August 1916 - 14 July 1989
Intelligence officer of Jade-Amicol

The transmitter featured here was used during WWII by the French resistance organisation Réseau Jade-Amicol (Jade-Amicol Network), which developed in 1940 in the southwest of France and worked for the British Secret Inteligence Service (SIS, MI6). The name of the organisation was a contraction of JADE – a precious stone – and the codenames of the British Captain Philippe Keun (AMI) and Claude Arnould (COL), a.k.a. (Colonel) Claude Ollivier 1 – the founder of the group [7].

Jade-Amicol had its northern headquarters at Le Couvent de la Ste Agonie, a convent at 147 Rue de la Santé in Paris (France), 2 headed by prior Mère Jean de la Croix. 3 Their activities mainly consisted of passing important intelligence information to London, organising and coordinating the French resistance and exfiltrating Jews and stranded RAF pilots via Bordeaux to Spain [7].

On 1 January 1943, 26 year old Alfonso Grisoni joined the Jade-Amicol network. He head been an aspirant Lieutenant with the French Artillery since the outbreak of WWII, but was in dismay with his superiors about the decisions of the military commanders to bend for the German agression and retreat. Together with several others he began resisting in August 1942 before being integrated with the Jade-Amicol group [4].

Grisoni eventually became an intelligence officer under direct command of COL (Claude Arnould, a.k.a. Colonel Ollivier); the leader of the group.
  
Alfonso Grisoni (left) in 1939, at the military school of Poitiers, before becoming aspirant Lieutenant with the French Artillery [4]

At the end of August 1943, he was given an Mk XV spy radio set and was sent on a long-term and dangerous mission to Vichy France — the part of France that was placed under control of Marshal Philippe Pétain [10] and collaborated with Nazi Germany [9]. His mission was to set up a local cell of Jade-Amicol, collect political, economic and military information, and pass it on to headquarters in Paris and the SIS in London. For more than a year he would live in Vichy under an assumed identity. The mission commenced without interruption until 30 September 1944.

In October 1944, Colonel Ollivier called Grisoni back to Paris to carry out other missions and for coordinating the cooperation with other French Resistance networks. He remained in service until late August 1945, a full year after the liberation of Paris and nearly four months after the end of the war. With his work Alfonso Grisoni was a P2 Agent 4 of the French intelligence service BCRA. 5

After spending a decade in Africa, Grisoni returned to France in 1959 to become Director of the office of the cabinet of the French Ministry of Cultural Affairs, under André Malraux, during the presidency of Charles de Gaulle. In the 1970s he was promoted to Deputy Director of the French Museums and Historical Monuments, for which he held office at the Louvre Museum in Paris.

Around the same time, from his house in Ajaccio (Corsica), he joined the Corsican movement for policital autonomy, which caused him to lose his influence at the French Ministry of Culture. He was transferred to the French Insitute of International Relations and later to the National Board of Veterans and War Victims (Anciens Combattants), where he became one of the directors.

After his retirement from public office, he settled permanently in Ajaccio, on the island of Corsica in the Mediteranian, where he became involved in several local cultural associations and was elected President of the Corsican Veterans. After an interesting life, Alfonso Grisoni passed away on 14 July 1989, exactly 200 years – to the day – after the start of the French Revolution [15].

  1. Claude Arnould was officially a Lieutenant-Colonel with the cover name Claude Ollivier and codename COL. He was known within the French resistance as Colonel Ollivier [8].
  2. Also: 122 Rue de L'Èbre, Paris (France). The street and the Convent were demolished in 1967/68.
  3. At the end of WWII, Mother Jean de la Croix (Henriette Frédé) received the Distinguised Service Order (DSO) for her wartime resistance work.
  4. A P2 Agent is a full-time intelligence officer of the French Resistance during WWII.  More
  5. The BCRA is also known as Deuxième Bureau, SR, BCRAM, DGSS, DGSE, DGER and SDECE.  More

Paris brûle-t-il?   Is Paris burning?
The 1966 French-American film Paris brûle-t-il ? (Is paris burning?) by René Clément gives a good impression of the work of the Jade-Amicol network during the last days of the German occupation of Paris. The film is an adaption of the book with the same title by Larry Collins and Dominique Lapierre about the liberation of Paris, and is shot at a number of historical locations.

One of these locations is Le Couvent de la Ste Agonie at 147 Rue de la Santé in Paris (France) — the original network's headquarters — where Mère (mother) Jean de la Croix was the Prior during the war. In one of the first scenes of the movie, the actual Jean de la Croix (real name: Henriette Frédé) plays a cameo role as a nun reading the bible in the patio [4].

 Wikipedia
 IMDb


After the war, she remained close friends with many of the former Jade-Amicol P2 Agents, including Boniface Leonelli, 1 Jo Cervotti 2 and Alfonso Grisoni. The image on the right shows Mère Jean de la Croix in 1953, signing the marriage register at the wedding ceremony of Alfonso Grisoni and his wife.
  
Mère Jean de La Croix (Sister Henriette Frédé) signing the marriage register of former P2 Agent Alfonso Grisoni [4]

  1. For five years after the war Boniface Leonelli was the head of the French National Police.
  2. Jo Cervotti later became Commissaire Divisionnaire with the French Police.

Alfonso Grisoni (left) in 1939, at the military school of Poitiers, before becoming aspirant Lieutenant with the French Artillery [4]
Claude Arnould (codename COL), a.k.a. Colonel (Claude) Ollivier, the founder of Jade-Amicol. Photograph via Wikipedia [8].
Mère Jean de La Croix (Sister Henriette Frédé) signing the marriage register of former P2 Agent Alfonso Grisoni [4]
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Alfonso Grisoni (left) in 1939, at the military school of Poitiers, before becoming aspirant Lieutenant with the French Artillery [4]
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Claude Arnould (codename COL), a.k.a. Colonel (Claude) Ollivier, the founder of Jade-Amicol. Photograph via Wikipedia [8].
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Mère Jean de La Croix (Sister Henriette Frédé) signing the marriage register of former P2 Agent Alfonso Grisoni [4]

Circuit diagram
Transmitter
Below is the circuit diagram of the transmitter, based on the drawings in Louis Meulstee's Wireless for the Warrior Volume 4 [1] and in Erling Langemyr's article in Hallo Hallo of August 1990 [5], although there are some differences between the two. We believe [1] to be correct.

At the left is the crystal oscillator built around a 6V6 or 6F6 valve (V1) It is driven by a crystal (X1) and has its own tuned circuit that consists of L2, C6, and C8. The oscillator starts by the virtue of a 5 pF capacitor (C3) that is connected between the anode and the G1 of V1. Note that this capacitor consists of two twisted wires. A tuning indicator (L3, La) is present to find the optimum. Switch S2 has to be set to the desired frequency range or to the frequency doubler option.


At the centre is the Power Amplifier (PA), which is built around a 6L6 valve (V2). At the right are two large coils (L4, L5) with multiple taps that form a tuned circuit with the variable capacitor C14. The frequency table inside the case lid specifies the setting of S4 and hence the selected tap. Only one of the coils L4/L5 is active, depending on the frequency range selected with S3.

The transmitter is powered by 6.3V (LT) for the filaments of the valves and a maximum of +450V DC (HT) for the anodes. In practice however, the transmitter works well with a nominal HT voltage of +350V. There is no power switch. As the morse key is connected in series with the cathodes of the valves (rather than the anode of V1) it is safe to touch the KEY terminals on the front panel.

Receiver
Below is the circuit diagram of the receiver, which is built around three 6SK7 valves. From left to right there is an RF amplifier (V1), a regenerative detector stage (V2) and an AF amplifier (V3). Compared to the earlier Mk V and the Mk VII, the receiver of the MK XV is much safer, as the RF amplifier (V1) prevents most of the oscillator signal from leaking to the antenna. Consequently, it was less prone to detection by the German Direction Finding teams of the SD, OrPo and Gestapo.


Note that the tuning capacitors C1a and C1b are adjusted in tandem, and that C5 is used for fine tuning. Potentiometer R1 is used as the volume control, whilst R8 is used to adjust the reaction level of the regenerative detector stage (V2). The circuit is powered by 6.3V (LT) and +240V (HT).

Power supply unit
Below is the circuit diagram of the continental version of the (PSU), which is based on the 5Z3 frectifier valve. At the left is the mains transformer (TR1) that has several taps to allow any continental mains voltage between 110 and 250V AC to be used, selectable with switch S1.


The PSU provides three voltages: 6.3V AC (LT) for the filiments of the valves, +240V DC (HT1) for the receiver (RX) and +450V DC (HT2) for the transmitter (TX). Note that S2 is used to select between RX and TX. The LT voltage is not switched, so that the filiments of all valves are heated as soon as the PSU is plugged into the mains. As a result, switching between RX and TX is instant.




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Interior
The transmitter is housed in a wooden enclosure that measures 290 x 140 x 120 mm. It has a paxolin (pertinax) 1 front panel that it bolted to the wooden case with 10 recessed screws. After carefully removing these screws, the entire transmitter can be lifted from the case. Note however, that the power cable is short and might have become stiff and brittle (and unsafe) over the years.

All controls are mounted to the paxolin front panel, whilst the electronic parts are fitted onto a metal chassis that in turn is bolted to the front panel. The image above shows the transmitter as seen from the rear top. The two valves (6V6 and 6L6) are fitted in octal sockets. Most of the passive components are fitted at the bottom side of the chassis, as shown in the images below.

  1. Paxolin is a flame retardant synthetic resin bonded paper, a composite material made of paper impregnated with a plasticized phenol formaldehyde resin. Also known as Pertinax or FR-2.  Wikipedia

Transmitter removed from the wooden enclosure
Rear view of the chassis
Interior top view
Interior - rear view
Oscillator
PA section
Internal morse key
Antenna coil (L4)
Interior - bottom section
Bottom view
Oscillator section
Oscillator (V1) wiring
PA section (range 3)
Coupling between oscillator (V1) and PA (V2)
PA valve socket wiring
Coupling between oscillator (V1) and PA (V2)
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Transmitter removed from the wooden enclosure
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Rear view of the chassis
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Interior top view
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Interior - rear view
E
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Oscillator
E
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PA section
E
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Internal morse key
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Antenna coil (L4)
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Interior - bottom section
E
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Bottom view
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Oscillator section
E
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Oscillator (V1) wiring
E
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PA section (range 3)
E
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Coupling between oscillator (V1) and PA (V2)
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PA valve socket wiring
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Coupling between oscillator (V1) and PA (V2)

Restoration
When we obtained the Mk XV transmitter from a family estate in November 2021, it's state was unknown. Although it might have been used after the war (for example as part of an amateur radio station), it had probably not been powered in the last 30 or 40 years. The rubber power cable had become rigid and brittle, and an original crystal appeared to be stuck in its socket.

In addition, the wooden enclosure was dry and urgently needed proper treatment. The device was removed from the wooden enclosure, so that its interior could be inspected. In the mean­time, the wooden enclosure was superficially cleaned and treated with a linseed-based oil.

The white text on the paxolin front panel is screen-printed rather than engraved, and is protected by a thin layer of shellac or varnish, which is likely to have degraded after many years of storage. This was also the case with our device, which had many loose varnish chips.
  
Wooden enclosure cleaned and treated with linseed-based oil

The problem was solved by using a medium-hard paint brush to wipe off the loose chips of the varnish layer. When doing this, be careful not to damage the white text though. There will also be parts of the front panel where the varnish doesn't want to come off. If that is the case, it is best to leave it in place. After half an hour of careful brushing, the front panel looked like new again.

The original 3422 kHz crystal that was stuck in the xtal socket at the front panel was carefully removed, after which all sockets were thoroughly cleaned. The stiff power cable was replaced by a neoprene cable with the same length and thick­ness, reusing the original Jones power plug.

Inside the device, the internal morse key had a major crack. Although it was still operational, it was better to repair it now, as otherwise it might fall apart later. The screw at the upper corner was loosened and the broken parts were glued back in place with a two-component adhesive.
  
Internal morse key

No further anomalies were found. All parts were still original and there were no after­market modifications. When we were confident that there were no short circuit on the power rails, the 6.3V LT voltage was connected. After the valves had heated up, the LT current was ~ 1.5 A.

Next, the HT voltage was applied, starting at +150V and then gradually raising it to +350V, whilst intermittently operating the morse key at the front panel. The internal components were carefully observed to ensure that nothing over­heated. At this point the HT current was 100 mA.

The oscillator tuning knob was set to the point where the indicator lamp produces maximum light, and then reduced to approx. 80%. Next, the PA tuning knob was turned to maximum output power, whilst observing the transmitted signal on a nearby communications receiver.
  
Crystal installed in socket

It appeared difficult to obtain a strong signal with the original 3422 kHz crystal that was found with the set, as it is slightly outside the specified range of the transmitter. The OSC tuning knob had to be set to its maximum. But with a different crystal at 3585 kHz, it worked as expected. After trying the device with various other crystals, we were satisfied that it was fully operational more than 80 years after it was built, with all of its original parts still intact. Here is what we did:

Wooden enclosure before restoration
Wooden enclosure after restoration
Wooden enclosure cleaned and treated with linseed-based oil
Front panel before restoration
Front panel after restoration
Transmitter removed from the wooden enclosure
4-pin Jones plug (transmitter power)
External morse key with rubber cable and connector
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F
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Wooden enclosure before restoration
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Wooden enclosure after restoration
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Wooden enclosure cleaned and treated with linseed-based oil
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Front panel before restoration
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Front panel after restoration
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Transmitter removed from the wooden enclosure
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4-pin Jones plug (transmitter power)
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External morse key with rubber cable and connector

Connections
Transmitter power
The LT and HT voltages for the transmitter are available on a Howard & Jones 4-pin female socket at the front panel of the PSU. Below is the pinout when looking into the socket. It is identical to that of the Mk VII (Paraset). A fixed rubber cable is used to connect the transmitter to the PSU.

  1. HT +360V
  2. not connected
  3. LT ~6.3V
  4. Ground (common)
    Pinout when looking into the (female) socket on the power supply unit
Receiver power
The LT andHT voltage for the receiver are available on a Howard & Jones 6-pin female socket at the front panel of the PSU. Bewlow is the pinout when looking into the socket. A fixed rubber cable is used to connect the receiver to the PSU.

  1. HT +150V
  2. not connected
  3. LT ~6.3V
  4. Ground (common)
  5. not connected
  6. not connected
    Pinout when looking into the (female) socket on the power supply unit
6V6 valve
The 6V6 is a beam-tetrode in a metal enclosure, developed in the mid-1930s by RCA for use in the audio stages of broadcast receivers. They are frequently found in single-ended or push-pull amplifiers, and even in today's vintage/retro valve-based amplifiers. Apart from the use in audio amplifiers, the 6V6 can also be found in the oscillator and PA stages of short-wave transmitters. In the Mk XV, the 6V6 is used in the oscillator.

 6V6 datasheet

Pinout of the 6V6 as seen from the bottom of the valve

6L6 valve
The 6L6 is a beam-tetrode in a metal enclosure, developed in the mid-1930s by RCA for use in (adio) amplifiers. It is believed to be the first true aligned-grid beam tetrode to have become available commercially in 1935. During and after WWII, the 6L6 was a popular valve for the PA-stage of a (clandestine) short wave transmitter. In the Mk XV, it is used as a power amplifier (PA) and (on the highest frequency bands) as a frequency doubler, In this configuration it produces a maximum power output of 10 - 15 Watts.

 6L6 datasheet

Pinout of the 6L6 as seen from the bottom of the valve

Specifications
Global
  • Year
    1943
  • Type
    Clandestine radio set
  • Purpose
    Agents, resistance organisations
  • Design
    SIS (MI6), Section VIII, Whaddon Hall/Little Horwood
  • Manufacturer
    SIS
  • Users
    SIS (MI6)
  • Orig. owner
    Jade-Amicol (Alfonso Grisoni)
Transmitter
  • Frequency
    3.5 - 16 MHz
  • Bands
    3 (see below)
  • Tuning
    Crystal-based
  • Valves
    2: 6V6, 6L6
  • Circuits
    Oscillator (6V6), PA (6L6)
  • Modulation
    CW
  • Output
    15 W
  • Power
    HT: 480V, 1 LT: 6.3V
  • Dimensions
    287 x 160 x 140 mm
  • Weight
    3.4 kg
Receiver
  • Type
    Regenerative
  • Frequency
    3 - 13 MHz
  • Bands
    1
  • valves
    3: 6SK7 (3x)
  • Circuits
    RF (6SK7), Detector (6SK7), AF (6SK7)
  • Modulation
    AM R/T, CW
  • Power
    HT: 240V, LT: 6.3V
  • Dimensions
    220 x 140 x 120 mm
  • Weight
    3.2 kg
Power supply unit
  • Valves
    1: 5T4, 6X5 or 5Z3
  • Mains
    100, 110, 125, 150, 200, 225, 250V AC
  • Dimensions
    300 x 160 x 140 mm
  • Weight
    6.8 kg
  • Versions
    (1) Pulser version in wooden box with 5T4 rectifier
    (2) Continental mains version in metal box with 6X5 rectifier
    (3) GBP Mk XV power inverter for 6V, with Carter 417 XV Dynamotor
Frequency bands   transmitter
  1. 3.5 - 5.2 MHz
  2. 5 - 8 MHz 2
  3. 8- 16 MHz 2
  1. In practice, an HT voltage of +350V is sufficient for testing.
  2. In these ranges the PA acts as a frequency doubler.

Users
The following users of the Mk XV are currently known:

  • SIS (MI6)
  • French resistance
  • Norwegian resistance
  • Danish stay-behind
Known serial numbers
Transmitter
Receiver
  • 6387
    Sold at an auction on 16 May 2020
Missing
The following items are currently missing from our collection:

  • Mk XV receiver
  • Mk XV power supply unit
  • Mk XV power inverter
  • Handbook
  • Morse key
Documents
  1. Attestation by Lieutenant Le Bar
    Testimonial by Lieutenant Le Bars (post-war liquidator of the Jade-Amicol network) to confirm that Mr. Alfonso Grisioni had worked during the war for Jade-Amicol, under direct orders from Lieutenant-Colonel Arnould (COL). Undated.

  2. Attentation by Forces Françaises Combattantes (FFC)
    Official document confirming that Mr. Alfonso Grisoni (born 27 August 1916) was in service as an intelligence officer from 1 January 1943 to 30 September 1944.
    No. 65410. Paris, 8 February 1949. Confirmed 11 March 1954.

  3. Proposition pour l'attribution de la Croix de la Guerre
    Nomination for the Croix de la Guerre, signed by Colonel Ollivier (Claude Arnould).
    Paris, 15 January 1946.
References
  1. Louis Meulstee, Wireless for the Warrior, volume 4
    ISBN 0952063-36-0, September 2004

  2. Pierre Lorain, Secret Warfare
    ISBN 0-85613-586-0. 1972. p. 44.

  3. Ben Nock (G4BXD), An original Wadden MkXV Transmitter in wood case
    Visited 2 November 2021

  4. Alain Grisoni, Personal correspondence
    October - November 2021.

  5. Erling Langemyr (LA3BI),
    Hallo Hallo, Volume 6, Nr. 3/90, August 1990. pp. 11-13

  6. Dave Gordon-Smith (G3UUR), The Agent Killer, A Spy Set with a Bit of a Reputation
    Electric Radio Magazine #352, September 2018. Updated 15 November 2021. pp. 2-15.
    Reproduced with kind permission of Electric Radio Magazine.

  7. Wikipedia, Réseau Jade-Amicol
    Visited 6 November 2021.

  8. Wikipedia, Claude Arnould
    Visited 8 November 2021.

  9. Wikipedia, Vichy France
    Visited 8 November 2021.

  10. Wikipedia, Philippe Pétain
    Visited 8 November 2021.

  11. Couvent des soeurs de la Sainte-Agonie durant de Seconde Guerre mondiale (WWII)
    Convent of the Sisters of Saint Agonie during the Second World War.

  12. Geoffrey Pidgeon, The Secret Wireless War
    ISBN 978-09560515-2-3. August 2008.[Heading]

  13. Brian Harrison (KN4R), Personal correspondence
    September 2018.

  14. Thomas Höppe (DJ5RE), Personal correspondence
    November 2021.

  15. Wikipedia, Fête nationale française
    Visited 18 November 2021.
     English version
Further information
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