BC221 BC-221 Frequency Meter Sets SCR211
SCR-211-A-B-C-D-E-F-J-K-L-M-N-O-P-Q-R-T
AA AC AE AF AG AH AJ AK AL
TM 11-300

BC-221-A BC-221-B BC-221-C BC-221-D BC-221-E BC-221-F BC-221-J BC-221-K BC-221-L
BC-221-M BC-221-N BC-221-O BC-221-P BC-221-Q BC-221-R BC-221-T BC-221-AA BC-221-AC
BC-221-AE BC-221-AF BC-221-AG BC-221-AH BC-221-AJ BC-221-AK BC-221-AL

SCR-211-A SCR-211-B SCR-211-C SCR-211-D SCR-211-E SCR-211-F SCR-211-J SCR-211-K SCR-211-L
SCR-211-M SCR-211-N SCR-211-O SCR-211-P SCR-211-Q SCR-211-R SCR-211-T SCR-211-AA SCR-211-AC
SCR-211-AE SCR-211-AF SCR-211-AG SCR-211-AH SCR-211-AJ SCR-211-AK SCR-211-AL


Circuit Diagram, Service Manual, Service Information,  Schematic Diagrams and Manuals

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The BC-221 heterodyne frequency meter
Comprises a dual-range VFO, a crystal controlled 1MHz oscillator, a mixer and AF amplifier.
Ranges of the VFO fundamental are 125kHz to 250kHz and 2MHz to 4MHz.
Both oscillators generate outputs rich in harmonics so that the instrument can be used well above its maximum design frequency of 20MHz.

When complete with headphones, spares, tools and batteries, as originally supplied, the equipment was designated SCR-211-(&) where (&) was a one or two-letter suffix.

The BC-221 is housed in either black-wrinkle finished aluminium alloy or matt-olive wooden cabinet.
Wooden-cased models were supplied with a khaki clip-on canvas cover that attached to the case with press-studs; metal-cased models with a padded carrying bag.

Power was supplied either from batteries or a mains power supply in a lower compartment accessible from the rear of the cabinet. Models B and Q were supplied with a battery tray.
 

In the UK the majority of mains power supplies were manufactured separately for the Ministry of Aviation during WW2.

A spare crystal was kept on the chassis itself in many models.
Tools inc. one or two Bristo wrenches (Nos.6 and/ or 8)
These resemble Allen keys, but are fluted rather than flatted.

The control panel itself is covered when not in use by a hinged lid that contains the units Calibration Book.
Each BC-221 was individually calibrated and the calibration book marked with the serial number of the unit.
The serial number is given on a metal or bakelite plate on the control panel and on the control-panel lid of metal-cased models. It can sometimes also be found stamped in paint on the units chassis.

Some metal-cased models had an Antenna terminal on the left-rear of the top of the case.
All wooden-cased models have their Antenna and Ground terminals on the front panel.

BC221 Calibrator.jpg (23432 bytes)


Frequency Meter BC-221 Set SCR-211
Was designed to provide a simple, accurate, and reliable crystal calibrated frequency indicating equipment for use in both the laboratory and in the field.
Since it is completely portable and self-contained, it was particularly adaptable for adjusting aircraft radio transmitters and radio receivers to any desired frequency in the range from 125 to 20,000 kcs.

COMPONENTS.
Each Frequency Meter Set SCR-211, as furnished , consists of the following component units:

Frequency Meter BC-221; size over all; height 13.13, width
10.13, depth 9.44;
Includes:

1 Frequency Meter BC-221 Chassis (wired)
1 Crystal Unit DC-9 (in operating position)
1 Calibration Book MC-177 (inside front door)
1 Wrench for Bristo 6 Set Screw (spare parts compartment)
1 Wrench for Bristo 8 Set Screw (spare parts compartment)
2 Sets of Vacuum Tubes (one set in service and one set in spare parts compartment)

Instruction Book for Frequency Meter Set SCR-211
Bag BG-81-D

Additional Spare Set of Vacuum Tubes (Packed in battery compartment)
Strap ST-19-A

Manual Circuits and
Layouts Available
Plus Additional Articles
Details Below
On Paper CD or Download
Click Here


The Manual Consists of  the Following

General information and instructions
Description
Introduction
General 
Frequency setting error 
Components 
Replaceable parts 
Power consumption
Installation and operation
Initial procedure 
Installation of batteries 
Antenna 
Headset 
Reading the dial 
Calibration Book MC-177-(&) 
Operating circuits 
Zero beat detection 
Correction in calibration 
Crystal check points 
Frequency measurements 
Precautions during operation 
Adjustments for field upkeep
Functioning of parts
General 
Circuit components 
Crystal Circuit
Variable frequency oscillator circuit 
Detector tube circuit 
Audio amplifying circuit 
Maintenance

General instructions 
Circuit trouble 
Moisture proofing and fungi proofing
Supplementary data
General 

Frequency Meter Sets SCR-211-A, SCR-211-C, and SCR-211-D.
Description 
Installation and operation 
Functioning of parts 
Maintenance 
Supplementary data 

Frequency Meter Sets SCR-211-B and SCR-211-Q.
Description 
Installation and operation 
Functioning of parts 
Maintenance 
Supplementary data 

Frequency Meter Set SCR-211-E.

Description 
Installation and operation 
Functioning of parts 
Maintenance 
Supplementary data 

Frequency Meter Sets SCR-21-1-F, SCR-211-J, SCR-211-K, and SCR-211-L.
Description 
Installation and operation 
Functioning of parts 
Maintenance 
Supplementary data 

Frequency Meter Sets SCR-211-M, SCR-211-O, SCR-211-R, and SCR-211-AC.
Description 
Installation and operation 
Functioning of parts 
Maintenance 
Supplementary data 

Frequency Meter Sets SCR-211-N, and SCR-211-AA.
Description 
Installation and operation 
Functioning of parts 
Maintenance 
Supplementary data 

Frequency Meter Sets SCR-211-P, SCR-211-T, SCR-211-AF, and SCR-211-AH.
Description 
Installation and operation 
Functioning of parts 
Maintenance 
Supplementary data 

Frequency Meter Sets SCR-211-AE, and SCR-211-AG.
Description 
Installation and operation 
Functioning of parts 
Maintenance 
Supplementary data 

Frequency Meter Set SCR-211-AK.
Description 
Installation and operation 
Functioning of parts 
Maintenance 
Supplementary data 

Frequency Meter Sets SCR-211-AJ, and SCR-211-AL.
Description 
Installation and operation 
Functioning of parts 
Maintenance 
Supplementary data 

BC221 1.jpg (34238 bytes)

BC221 2.jpg (39121 bytes)

BC221 3.jpg (38587 bytes)

Manual Circuits and
Layouts Available
Plus Additional Articles
Details Below
On Paper CD or Download
Click Here


BC221 BC-221 Frequency Meter SCR211 SCR-211-A-B-C-D-E-F-J-K-L-M-N-O-P-Q-R-T AA AC AE AF AG AH AJ AK AL TM 11-300
Manuals are Available Worldwide as a Download on CD or Paper Copy.

BC-221-A BC-221-B BC-221-C BC-221-D BC-221-E BC-221-F BC-221-J BC-221-K BC-221-L
BC-221-M BC-221-N BC-221-O BC-221-P BC-221-Q BC-221-R BC-221-T BC-221-AA BC-221-AC
BC-221-AE BC-221-AF BC-221-AG BC-221-AH BC-221-AJ BC-221-AK BC-221-AL

SCR-211-A SCR-211-B SCR-211-C SCR-211-D SCR-211-E SCR-211-F SCR-211-J SCR-211-K SCR-211-L
SCR-211-M SCR-211-N SCR-211-O SCR-211-P SCR-211-Q SCR-211-R SCR-211-T SCR-211-AA SCR-211-AC
SCR-211-AE SCR-211-AF SCR-211-AG SCR-211-AH SCR-211-AJ SCR-211-AK SCR-211-AL


Technical Installation & Operation Manual with Circuits and Layouts Covering
all above models
Manual 180 A4 pages worldwide


Or the Manual with Circuits and Layouts Covering  just the BC221 M SCR-211-M model
Manual 38 A4 pages worldwide


Or the Manual with Circuits and Layouts Covering  just the BC221 P & BC221 T SCR-211 P SCR-221-T model
Manual 42 A4 pages worldwide


Mains Power Supply "Rectifier Power Unit RA-133 TM 11-300"
Technical Bulletin with Circuits and Layouts Covering the models listed below.
 

BC-221-B BC-221-M BC-221-N BC-221-O BC-221-P BC-221-Q BC-221-R BC-221-T BC-221-AA BC-221-AC
BC-221-AE BC-221-AF BC-221-AG BC-221-AH BC-221-AJ BC-221-AK BC-221-AL BC-221-AN

SCR-211-A SCR-211-B SCR-211-C SCR-211-D SCR-211-E SCR-211-F SCR-211-J SCR-211-K SCR-211-L
SCR-211-M SCR-211-N SCR-211-O SCR-211-P SCR-211-Q SCR-211-R SCR-211-T SCR-211-AA SCR-211-AC
SCR-211-AE SCR-211-AF SCR-211-AG SCR-211-AH SCR-211-AJ SCR-211-AK SCR-211-AL SCR-211-AN


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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
 
"BC-221 SCR-221 Manual Covering All Models 180 Pages"
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"BC-221 SCR-221 Manual Covering M model only 38 Pages"
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"BC-221 SCR-221 Manual Covering P & T models only 42 Pages"
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"Rectifier Power Unit RA-133 TM 11-300 Manual Covering the Mains Power Supply Only 13 Pages"
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"Additional Articles 27 Pages"
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Revised: January 20, 2016