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Finnish (Swedish) spy radio sets

Kyynel (English: tear) was a range of clandestine transmitters and receivers, also known as spy radio sets, devloped before, during and after World War II, by Holger Jalander and manufactured by the Finnish Army Depot Company Munkkiniemi near Helsinki (Finland). Despite the fact that Finland was collaborating with Germany during the war, some Kyynel sets were developed outside the view of the Germans. Some of them were supplied secretly to the Swedish resistance.


Kyynel sets on this website
Kyynel M-5 transmitter
Kyynel M-10 and M-10X
Kyynel M-11 and M-11X
Alternative names
So far, the following alternative designators have been identified [5]:

  • VRHA
  • VRHA
  • VRHA/3
    M4/M7 in cardboard box (1941)
    M5/M7 in cardboard box (1941)
    M10 (1942)
    M10X, crystal version (1943)
    M10X, crystal version, Stella Polaris (1943)
    M11 (1943)
    M12/M7 (1943)
    M10 or M11 in metal container
  1. Fix-tuned to 166 kHz (1807 metres)
  2. Serial numbers with the letter 'B' were manufactured in Sweden, as part of Operation Stella Polaris [3][4].


Kyynel is the Finnish word for tear. It was used as the codename for a range of clandestine radio sets. Development of the range started before the winter war of 1939, when the Army recognised the increased need for light-weight transceivers. Until that time, all Finnish radio sets used by the Army had been heavy and bulky, and were unsuitable for remote patrol liaison officers [2].

As radio amateurs already had valuable experience with radio communication under varying conditions, the development team consisted mainly of radio hams. The group worked under supervision of reserve-captain Holger Jalander and the initial designs were largely based on existing German agent radio sets weighting 15kg. These developments were not very successful. An additional problem was that suitable parts and tools were difficult to obtain at the time.

Nevertheless, the team succeeded in producing a small portable radio station of which the first prototypes were tested at the beginning of 1940.

Construction work on the radios was carried out in utmost secrecy in a heavily guarded cottage at Lake Tuusula. The enterprise was later moved to a better location in Röykkää and ultimately to Nystad (Finland) [2]. Already in the early stages of the development, Jalander had decided to use die-cast aluminium enclosures for the radios. Not only did he save on weight this way, it also allowed the radios to be made truly watertight.
Kyynel M5 in straight-up position

The developments eventually resulted in the production of the early Kyynel models M-4, M-5 and TÖPÖ (stump) which used German valves like the DLL21 and DF11 (e.g. produced by Telefunken). For unknown reasons, only the M4 and M5 transmitters were housed in a watertight enclosure.

The M7 receiver that was used with the M4 and M5, was housed in a regular aluminium case.

In 1941 or 42, Jalander submitted two samples of the M4/M7 combination to the Germans for evaluation, after which the Germans copied and improved the design, probably for their own use. The result is shown in the image on the right. Interestingly, the Germans had used watertight enclosures for both transmitter and receiver. Furthermore, the devices have 4 compartments, rather than 3, to hold a spare LT battery. The cases are painted grey and the caps have text.
German copy of the Finnish M4 and M7 - Collection Günter Hütter [5]

Very little is known about the German copy, but at least one set has survived [5]. It is currently unknown who the potential users of these devices were — both the German Abwehr and the SD had their own devices — and it seems likely that only a small quantity was ever manfufactured.

In 1942, the earlier models were followed by the M-10 which was effectively a combination of the M-5 transmitter and the M-7 receiver. The radio set was designated VRHAG (P-12-24) and the first wiring diagram was drawn on 13 July 1942.

A few years later, a crystal version of the radio had to be developed, but it appeared to be very difficult to obtain crystals at the height of WW-II. Again, radio amateurs came to the rescue when reserve-lieutenant Toivo Leiviskä, an electronics engineer, demonstrated how they could be made manually [2]. This resulted in the M-10X model.
Image copyright Antero Tanninen [2]

The crystal-driven M-10X was not only used in Finland, but was also sold to Sweden in late 1943 and early 1944. The first 25 units were delivered prior to Operation Stella Polaris 1 in Finland, followed by another 75 units that were produced by Major Rangvald Lautkari in his workshop in Lindingö. The components for this production run had to be shipped over water from Nystad [2]. The serial numbers of the radios that were manufactured in Sweden, are suffixed by the letter 'B'.

After World War II had ended, production of the M-10 and M-10X continued, as the Cold War had meanwhile started. The M-10(X) was eventually modified and continued life as the M-11 and the M-11X — suitable for modern crystals — both of which remained in production until ~ 1959.

  1. Operation Stella Polaris was a covert operation in which Finnish signals intelligence records, equipment and personnel were transported to Sweden in late September 1944, to prevent them from falling into Russian hands [4].

Kyynel M-5
The Kyynel M-5 was a watertight transmitter, developed in 1940 as the successor to the M-4. It was commonly used in combination with the Kyynel M-7 receiver, but could also be used with other receivers.

The device works in the 3.5 to 6 MHz frequency range and produces an output power of 500 mW.

 More information

Kyynel M-5 transmitter with caps removed

Kyynel M-10   M-10X
The M-10 was developed in 1942, during the early stages of WWII, followed by a version for quartz crystals – the M-10X – in 1943.

Although Finland was collaborating with Germany at this time, some of the sets were secretly delivered to the Swedish resistance. in 1944, some of the M-10X sets were even manufactured in Sweden.

 More information

Kyynel M-10X transceiver

Kyynel M11   M-11X
After WWII had ended, production of the M-10 and M-10X continued, as meanwhile the Cold War had started, and more sets were needed for reconnaissance, espionage and Stay-Behind.

The set was eventually fitted in a metal container and modified for use with modern crystals – such as the ones from American military surplus – after which it was renamed M-11 and M-11X.

 More information

Kyynel M-11X with battery compartment on top

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

  2. Antero Tanninen (OH1KW), Fjärrpatrullmännens radio 'Kyynel'
    Translated to Swedish and edited with permission of the author by Thomas ON6NT.
    Date unknown. Retrieved, September 2012.

  3. Wikipedia, Kyynel (radio)
    Retrieved June 2020.

  4. Wikipedia, Operation Stella Polaris
    Retrieved May 2022.

  5. Günter Hütter, German copy of M4 and M7 devices
    Personal correspondence, May 2022.

  6. Kouvolan Putkiradiomuseo, KYYNEL, "Siiri" P-12-24
    Visited 11 May 2022.
Further information
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© Crypto Museum. Created: Thursday 27 September 2012. Last changed: Wednesday, 11 May 2022 - 16:34 CET.
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