BC-611

Radio Set SCR-536 is a very compact receiver - transmitter resembling an oversize telephone hand set. Complete with batteries, antenna, transmitter, receiver - and handset in one case. The BC-611 is a handheld radio commonly known as the first "walkie talkie"

Specifications

Frequency Range

3.5 - 6.0 mHz

Modulation Type

AM

Number of Crystals

One transmitter and one receiving crystal required per channel

Preset Frequencies

One preset Channel Provided

Antenna

44 Inch whip antenna - telescopes into set box, receiver is turned on when the antenna is extended

Tuning

Crystal

Power Source

Self contained dry batteries

Power Output

.027 Watts

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Removal From the Case

To remove the circuits from the case for service"

1. Open the bottom cover
2. Unplug the mic and speaker wires
3. Unscrew the top screw
4. Pull the radio out from the bottom.

Reinstallation in the Case

When reinserting the radio into the case, take care to align the radio on the guide slots. (see images below)

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Tuning

Tuning is accomplished by means of two separate crystals an antenna coil, and a tank coil. The receive crystal frequencies are 455 kHz above the desired frequency. for example a crystal frequency of 4340 will give you a receive frequency of 3885 kHz. Often the receive crystals for the BC-611 will have the crystal frequency on the front and the actual receive frequency on the back.

BC-611 receive crystals show the crystal frequency on the front and the receive frequency on the back

Transmit Crystal is marked with the primary frequency only, the above crystal is Transmit frequency of 3245 kHz. There is also a tuning lug that is matched to the Crystal

© 2014 Army Radio Sales Company, Used with Permission

FT-243 Tuning Crystals and antenna coils are stored in BX-49

The transmit frequency can be seen through the case

Receive and Transmit Crystals

Tuning Coil

MWO (Maintenance Work Orders

MWO SIG 11-235-1

Authorizes the replacement of die casr press-to-talk switch parts with steel stamped parts to minimize breakage in service. (8 August 1944)

MWO SIG 11-235-2

Authorizes the addition of a polystyrene antenna support insulator at the top of the chassis to provide firmer support for the telescopic rod antenna (25 August 1944)

MWO SIG 11-235-3

Authorizes the replacement of molded bakelite microphone and earphone caps by aluminum caps (18 October 1944)

MWO SIG 11-235-4

Authorizes the replacement of the top chassis mounting bracket with a stronger bracker held in place by two machine screws. (4 January 1945)

MWO SIG 11-235-5

Authorizes the necessary drilling of the bottom cover assembly to mount an external headset jack for use of Headset HS-30-( ) in connection with the Homing Modification Kit MC-619 (25 January 1945)

MWO SIG 11-235-6

Repeats MWO SIG 11-235-3 and adds MC-162 to the earphone and M-367 to the microphone caps for hot weather breakage and cold weather personnel protection. (1 April 1945)

MWO SIG 11-235-7

Added copper wire ground buss between all socket ground plates

MWO SIG 11-235-8

Adds a metal clip to the bakelite ON/OFF switch on the antenna bottom section.

Related Files

TM 11-235

Radio Sets

SCR-536-A, -B, -C, -D, -E, -F

May 1945

TM 11-4019

Radio Receiver and Transmitters

BC-611-A, -B, -C, -D, -E and -F

Repair Instructions

July 1945

TM 11-310

Schematic Diagrams for Maintenance of Ground Radio Communication Set

October 1942