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Biscuit Tin Receiver
The MCR-1 was a small receiver, developed in 1943 by Captain John Brown,
for use by the SOE. It was used both stand-alone and as part of complete
spy transceivers.
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The official name for this receiver is Type 36/1, but it is commonly
known as the MCR-1 (Miniature Communication Receiver). Over 30,000 units were produced by the British
Philco corporation and many of these were dropped over occupied
European territory for reception of broadcasts by resistance groups.
The receiver has 5 valves (4x 1T4 and 1x 1R5) and has an IF of 1.73 MHz.
Sensitivity is approx. 10 µV (for 1 mW audio output)
and the output power is approx. 5-8 mW into 800 ohms headphones.
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The MCR-1 is housed in a gray painted rectangular case, with connections
for a coil block at one end. The complete set consists of the receiver,
a similar shaped power supply, 4 coil blocks, a pair of headphones, a
wire antenna, some spare components and wires for connecting it to the mains.
Everything was packed into watertight tinned-steel bisuit tins, hence the
nickname: Biscuit Tin Receiver.
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The receiver had a fixed power cable with a standard LT/HT battery connector,
so that it could be powered from standard dry battery packs (7.5V/90V)
or from the external power supply unit.
The unit consumes approx. 50 mA on the LT rail and between 5 and 8 mA
on the HT rail.
External power supply units are extremely rare and have often been
lost over time. They are rather dangerous as well as one of the secundary
power lines is connected directly to the mains. In other words:
if the main power plug is connected the wrong way around, the (metal) case
carries the live mains voltage!
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The MCR-1 covers all frequencies between 150 kHz and 15 MHz, divided
over 4 frequency ranges.
A tuning coil is fitted to one end of the receiver and four such coils
were supplied, one for each frequency range:
- 1: 150 kHz - 1.6 MHz
- 2: 2.5 MHz - 4.5 MHz
- 3: 4.5 MHz - 8 MHz
- 4: 8 MHz - 15 MHz
The tuning scale is linear and a suitable frequency conversion scale
is printed on each coil.
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After the war, Belgian Philips subsidary MBLE produced copies of the
MCR-1 for use by the newly formed stay-behind organisation.
These units were pained green/brown and came in a canvas bag, together
with the accessories, such as additional coils and antenna.
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The image on the right shows such a post-war MBLE copy of the MCR-1.
The unit is much better built than the war-time version and uses
higher-grade components, but is otherwise identical.
It was supplied without an external power supply, which suggests
that it was always battery-operated.
More images of this unit below.
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- Louis Meulstee, Wireless for the Warrior, volume 4
ISBN 0952063-36-0, September 2004
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© Copyright 2009-2011, Paul Reuvers & Marc Simons. Last changed: Tue,12 Apr 2011.22:37:34
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