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Motorola
Special Forces hand-held two-way SW radio
BC-611, also known as SCR-536, 1 handy talkie or
walkie talkie, was a valve-based hand-held two-way
radio transceiver, developed in 1940 by Don Mitchell at
Galvin Manufacturing (now: Motorola) for the US Army.
It was used througout World War II (WWII),
in particular during the landings on Sicily (Italy), North Africa and,
in June 1944, at Omaha Beach in Normandy (France).
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The radio is housed in a green water resistant enclosure that measures
320 x 90 x 80 mm and weights 2.3 kg, batteries included. It operates
in simplex on a single channel (choosen from 50 channels) in
the 80 m SW radio band between 3.5 and 6 MHz, using
Amplitude Modulation.
The unit is powered by internal LT and HT batteries that are installed
behind a hinged panel at the bottom. There is no power switch; the device
is switched on simply by pulling out the antenna. At the side is a large
PTT-switch and a shield on which the current frequency is written.
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The BC-611 was developed in 1940 by an team led by Don Mitchell, chief enigineer
at Galvin Manufacturing (now: Motorola).
It was the first true self-contained hand-held
unit to be widely deployed and was mass produced from July 1941 onwards. By the end of
WWII, 130,000 units had been made by Motorola. The BC-611 was also produced by
other manufacturers, including ERLA.
After the war, the BC-611 remained in production in several countries until 1956,
and was made under licence by various foreign manufacturers, including LGT
in France, Autophon in Switzerland (sold as FOX SE-100)
and NEC in Japan. In some European countries, such as The Netherlands, the BC-611
was used for several years after the war by the re-established Police Force [6].
The devices were also heavily used during the Korean War (1950-1953).
For re-enactment, low-cost BC-611 reproductions (replicas) are available
today from various sources [4].
A great historical account was given in 1977 by Elmer Wavering – former handler
of governmental contracts at Galvin Manufacturing – who personally knew
Don Michell — developer of ther BC-611 — and Paul Galvin — the company director —
both of which had meanwhile passed away [7].
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SCR-536 is the designator of the complete radio set, whilst BC-611 refers
to the transceiver only.
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During WWII, six models of the BC-611 were released, suffixed by the letters A-F.
As the chassis doesn't carry a serial number, and the case is identical for all models,
the interior doesn't always match the case and, hence, the model number. The repair manual
provides help on identifying the different models [B]. Below is a non-exhaustive list
of the most obvious differences:
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- Initial version of the BC-611.
- Resistor R25 added.
- R28 added. Antenna support insulator added. 1,2
- Polystyrene antenna insulator instead of ceramic, Aluminium mic and speaker caps.
- Different PTT actuating linkage. Phenolic membranes.
- Sockets added for external microphone and headset (bottom cover assembly).
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Not on early BC-611-C models. This insulator had to be added to existing models
when they were returned for repair, in accordance with MWO SIG 11-235-2.
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On BC-611-C units with manufacturer code CZE (made by ERLA),
segments E and F of the Push-To-Talk switch (PTT) are swapped to allow for
shorter connections.
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When altering the channel (fitting different crystals and coils)
or re-aligning the radio after a repair,
it is necessary to remove the interior from its enclosure, and temporarily
install it in the test case shown in the image on the right.
The Test Case is nearly identical to the original enclosure, but has holes
in its body through with the adjustment points can be reached.
Once alignment is complete, the interior can be re-installed in its own
enclosure.
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A rather unique example of a post-war BC-611-F, is the one shown in the image
on the right. It was manufactured in March 1952 by the Nippon Electric
Company (NEC) in Tokyo (Japan).
The unit shown here is configured for 5127.5 kHz and has serial number 00001.
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Device Handheld two-way radio Developer Don Mitchell Manufacturer Galvin Manufacturing (Motorola), span class) User US Army Year 1940 Production 1941-1956 Quantity 130,000 (by the end of WWII) Frequency 3.5 - 6 MHz Band 80 m (SW) Channels 1 (from a set of 50) 1 Spacing 40 kHz Modulation AM Sensitivity 3 - 5µV Valves 5 (see below) Output 360 mW IF 455 kHz Antenna 1 m (40") telescopic rod Range 200 m - 1.6 km (over land), or 4.8 km (over salt water) Batteries LT: 2 × BA-37 (1.5V)
HT: 1 × BA-38 (103.5V) Current LT: 250 mA (300 mA when transmitting)
HT: 11 mA (35 mA when transmitting) Duration ~ 1 day (19 hours) Weight 1.75 kg (2.3 kg with batteries)
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Channel selected with plug-in crystals and coils.
Each unit is aligned for a single channel.
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1 x 1R5 VT-171 1 x 1S5 VT-172 1 x 1T4 VT-173 2 x 3S4 VT-174
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BX-48 Box for spare crystals and valves (5 sets) BX-49 Box for spare crystals and valves (24 sets) BG-162 Bag for batteries (BA-37, BA-38) CH-146 Chest for equipment CH-233 Chest for spare tubes, crystals (400 items) CH-312 Test case for IE-37 tuning unit CS-144 Parachute case CS-156 Canvas case
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HS-30 Headset T-30 Throat microphone T-45 Upper lip microphone
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ME-36 Maintenance kit MC-619 Homing modification MC-534 Frequency conversion kit MC-518 Frequency conversion kit IE-15-A Test Equipment FT-252 Test Stand CS-81 Test Case I-56 Test Set IE-17 Test Equipment I-135 Test Unit
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Foreign manufacturers
post-war
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- BC-611
- SCR-536
- Handy Talkie
- Walkie Talkie
- Banana
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- Wikipedia, SCR-536
Retrieved June 2022.
- Gil McElroy (VE3PKD), A Short History of the Handheld Transceiver
ARRL. QST, January 2005.
- Klaus-Peter Jung (DH4PY), Bananas
Retrieved June 2022.
- 90th Infantry Division, What Price Glory, BC-611 Radio Reproduction
25 May 2014.
- Radiomuseum, SCR-536 Radio Set BC-611 (Variants A, B, C, D, E and F)
Retrieved June 2022.
- Scannermuseum, Etherbeheer: Verbindingen bij de Amsterdamse Politie
Visited 7 June 2022.
- Elmer H. Wavering, Letter to Mr. T.F. Walkowicz
Galvin/Motorola, 23 March 1977.
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© Crypto Museum. Created: Tuesday 07 June 2022. Last changed: Thursday, 11 August 2022 - 09:11 CET.
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