BBC-224 BC-348 BC-224-E BC-224-F BC-224-G BC-224-H
BC-224-K BC-224-L BC-348-E BC-348-H BC-348-J
BC-348-K BC-348-L BC-348-M BC-348-N BC-348-O
BC-348-P BC-348-Q BC-348-R BC-348-S Radio Receiver


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BC348
The B-348 is a compact American made communications receiver, which was mass-produced during the war for the U.S. Army Air Force.
The BC-348 series ran to several  mark letters during its long production history.
Although the outside appearances were similar, internally there were considerable divergences, particularly with the later models.
The basic common specification was of a superhet having two r.f. stages, frequency-changer, three i.f. stages, detector / a.g.c. and output stage.


There was no intermediate a.f amplifier between detector and output.
The frequency-changer stage in the earlier marks consisted of separate mixer and local oscillator valves, later altered to a single-valve configuration.
The early marks had a b.f.o. combined with the 2nd i.f. amplifier, whilst the later types had it combined with the detector / a.g.c. valve.

The Frequency Coverage was the same for all marks:
200-500 Hz
1.5-3.5 MHz
3.5-6 MHz
6-9.5 MHz
9.5-13.5 MHz
13.5-18 MHz.

The Power Source being the aircraft 24v service battery, the valve heaters were arranged in series-parallel to present a nominal 25.2v load.
The h.t. was supplied by a dynamotor rated at 28v input and approximately 235v output at 75mA.
Why 28v you may ask ? well a lead-acid accumulator of nominally 24v (12 two-volt cells) gives 26.4v when fully charged, (2.2v per cell). However, when on charge the terminal voltage will be of the order of 28v, hence the input rating of the dynamotor. 

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Resistors were also placed in the heater circuit to reduce the voltage, as the battery was expected to be on charge throughout operational flights.
Similarly a nominal 12v battery gives 13.2v fully charged and a terminal voltage of around 14v on charge.

Another series of receivers numbered BC-224 was in concurrent production, these models being identical with the BC-348 except for the power source a 12.6v battery.


The Manual Contains similar information to the Following depending on model

On the BC348 Name Plate there will be a letter of the alphabet please quote this with your order 

TABLE OF CONTENTS

GENERAL DESCRIPTION


General 
Component Units 
Cabinet 
Chassis 
Dial and Mask Assembly 
Dynamotor 
I-F Transformers, Crystal Filter, C.W Oscillator 
Mounting 
Panel 
Plug 
R-F and Oscillator Units 

INSTALLATION AND ADJUSTMENT 

Initial Procedure 
Unpacking 
Inspection 
Installation 
Mounting 
Electrical Connections 
Elimination of Electrical Interference 
Mounting the Receiver 
Antenna and Ground Connections 
Preparation for Use 
Inspection 
Controls

OPERATION

Procedure 
Operating Test 
Reception 

MECHANICAL AND ELECTRICAL CHARACTERISTICS

Circuits 
Frequency Range and Bands 
Input Coupling 
Radio Frequency Amplifier 
First Detector 
Heterodyne Oscillator 
Intermediate Frequency Amplifier 
C-W Oscillator 
Crystal Band-Pass Filter 
Second Detector 
Output 
Description 
Constant Internal Receiver Noise 
Dynamotor DM~28~(*) 

MAINTENANCE 

Inspection 
Dynamotor Service and Maintenance 
Removal from Chassis 
Lubrication 
Commutator 
Bearings 
Reassembly 
Power Rating 
Removal of Front Panel 
Dial and Mask Assembly 
Servicing the Dial and Mask Assembly 
Removal 
Disassembly 
Dial Replacement 
Stop Arm Replacement 
Replacement of Dial and Mask Assembly 
Dial Calibration 
Removal of Antenna, R-F Detector and Oscillator Units 
Trouble Location and Remedy 
Quick Check 
Sensitivity 
Trouble Location and Correction Procedure 
Equipment Required 
Weak or No Signals on All Bands, Modulated Reception 
Weak or No Signals on Any One Band, Modulated Reception 
Weak or No Signals on All Bands-C-W Reception (Modulated Reception Normal)
Measurements with Test Set 1.56-A 
Failure of Dial Lights 

SUPPLEMENTARY DATA 

General 

TABLE OF REPLACEABLE PARTS 

DRAWINGS 

LIST OF ILLUSTRATIONS


Radio Receiver BC-348J 
Radio Receiver BC-348-J, Tube Positions 
Radio Receiver BC-348-J, View of Front Panel 
C-W Oscillator Switching 
Crystal Filter Circuit 
AVC Connections 
MVC Connections 
Dynamotor DM.28-J and Filter 
Radio Receiver BC-348-J, Dial and Mask Assembly 
Trouble Location and Correction Chart 
Crystal Filter Coil 
Socket Voltages 
Location of Trimmer Capacitors 
Radio Receiver BC.348-J, Front View 
Radio Receiver BC-348-J, Rear View of Chassis 
Radio Receiver BC-348-J, Top View of Chassis 
Radio Receiver BC-348-J, Bottom View of Chassis 
Radio Receiver BC-348-J, Partial Bottom View 
Mountings FT-154-J, FT.154-Q, and FF-154-AA with Plug Assemblies, Rear View
Radio Receiver BC-348-J, Front View of Cabinet 
Antenna Unit 
R-F Unit 
Detector Unit 
Oscillator Unit 
I-F, C-W Oscillator and Crystal Coil Assemblies 
Radio Receiver BC-348-J, Schematic Diagram 
I-F Transformers, Wiring Diagram 
Radio Receiver BC-348-J. Outline Dimensional Sketch 
Mounting FT-154-J, Drilling Plan 
Radio Receiver BC-348-J, Wiring Diagram of Chassis 
Antenna, R.F, Detector and Oscillator Units, Wiring Diagram 
Radio Receiver BC.348-J, Plug Connections 

BC348 2.jpg (20553 bytes)

BC348 3.jpg (27282 bytes)

BC348 4.jpg (26272 bytes)


BC 348 BC348 BC-348 BC 224 BC224 BC-224 
BC-224-E BC-224-F BC-224-G BC-224-H BC-224-K BC-224-L
BC-348-E BC-348-H BC-348-J BC-348-K BC-348-L BC-348-M BC-348-N
BC-348-O BC-348-P BC-348-Q BC-348-R BC-348-S Radio Receiver

Manuals are Available Worldwide as a Download on CD or Paper Copy.

On the BC-348 Name Plate there will be a letter of the alphabet please quote this with your order.

All the text and diagrams are sharp and clear, some of the photographic images on our original copies were dark.

We will have duplicated them with other images wherever possible.

All data comes with a full refund option if not as expected : )


Manual including the Circuits with Component lists and layouts between 70 & 98 A4 pages worldwide

Printed Paper Copy or on CD are Plus Postage.
( For all Payment Options plus UK and Overseas Postage )
( Please Click the Payment Links Below )


Additional Articles 27 Pages as follows : -

BC348 Modified

( Notes on adapting a useful receiver for amateur Operation )

The BC-348 Receiver
( Modifications and Improvements )

Modification Details for the BC-348 Part I
( Power Supply, Signal Frequency Circuit Alterations, Valve Changes, Improving Audio Out, Adding Noise Limiter and S Meter,
 Converter for 10 Meters, Fault Tracing Sequence )


Modification Details for the BC-348 Part II
( Further Circuit Data )

Modification Details for the BC-348 Part III
( Range Extension, Converter for 10 Meter Operation, Alignment Details, Servicing Data, Voltage & Current Tables )

Improvements for the BC-348Q
( Noise Limiting, More Audio Output, Controllable RF Gain )
 
Articles 27 A4 pages worldwide

BC 348 BC348 BC-348 BC 224 BC224 BC-224
BC-224-E BC-224-F BC-224-G BC-224-H BC-224-K BC-224-L
BC-348-E BC-348-H BC-348-J BC-348-K BC-348-L BC-348-M BC-348-N
BC-348-O BC-348-P BC-348-Q BC-348-R BC-348-S Radio Receiver

Printed Paper Copy or on CD are Plus Postage.

( For all Payment Options plus UK and Overseas Postage )
( Please Click the Payment Links Below )

We do all we can to provide the very best that is available for you.
But in the unlikely event that any data should not be as you expected.
A refund is always available. Kind Regards Allen and Alanna.


Manuals are Available Worldwide as Paper Copy on CD or as a Download

Thank you for your interest. Allen and Alanna G0RIT
Should you wish to purchase
 
Manual containing between 70 and 98 pages including the Circuits with Component lists and layouts.
On the BC-348 Name Plate there will be a letter of the alphabet please quote this with your order

  For Worldwide Payment Options and Delivery Details

 

"Additional Articles 27 Pages"
   For Worldwide Payment Options and Delivery Details

 

"Special Offer Manual and Additional Articles " Saving over 7.50 depending on format "
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Revised: January 20, 2016