M-7 was a compact valve-based
clandestine radio receiver, also known as a
spy radio receiver,
developed shortly before World War II by
the Finnish
Army Depot Company Munkkiniemi near Helsinki (Finland),
and introduced in 1941. In was commonly used in combination with the
Kyynel M-5 transmitter.
The design of the receiver was later also used
in the M-10 and M-11 radio sets.
Circuit diagram
References
Louis Meulstee, Wireless for the Warrior, volume 4
ISBN 0952063-36-0, September 2004.
