Marconi B28 Receiver
CR100 CR100/1 CR100/2 RAF 1297
CR100/3 CR100/4 CR100/5 CR100/6 CR100/7 CR100/8 RX


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The Marconi CR100 B28
A self - contained Communications Receiver of super heterodyne type with AVC  for use on CW or Phone reception.


As with other versatile equipment of the Forties, the CR100 was subject to a number of variations,  most of them minor  in  specification, to suit particular Service needs.

Basic Circuit :- 
Two RF amplifiers, both KTW62 or 6K7G. 
Mixer - X66 or 6K8G. 
Local oscillator - KTW62 or 6K7G.
IF amplifier- three KTW62 or 6K7G.
CW oscillator - KTW62 or 6K7G.

Detector agc and audio amplifier - DH63 or 6Q7G. 
Output - KT63 or 6V6G.
Mains rectifier - U50 or 5Y3G.

Frequency Range :-
60 kc/s to 420 kc/s and 500 kc/s to 30 Mc/s in 6 bands. 
Band1:- 60 to 160 Hz.
Band 2:- 160 to 420 kHz.
Band 3:- 500 to 1400 kHz.
Band 4:- 1400 to 4000 kHz.
Band 5:- 4000 to 11000v kHz.
Band 6:- 11000 to 30000 kHz.

Power Supply :-
A built in 200 - 250 volt AC power unit is positioned at the rear right of the chassis, sensibly remote from the tuned circuits.

Consumption is 85 watts.

Manual and Circuit
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Receiver Output :-

Loudspeaker (3 ohms or 1000 ohms) 2 watts maximum.
Line (600 ohms) of the order of 2mW.
Phones  (high or low resistance) depending on impedance of Phones and Receiver Edition.

Modified Editions
A number of Editions existed carrying modifications to suit the needs of various Services, the principal models being : -

CR100 CR100/1 CR100/2 RAF 1297 CR100/3 CR100/4 CR100/5 CR100/6 CR100/7 CR100/8 Mod.

Weight
82 lbs

CR100 Chassis.jpg (24231 bytes)


PCR100  Prototype.
Low phone level. "B" gauge phone jacks. 
3 ohm loud speaker. 

CR100/1 B28 W2835 Admiralty.
High phone level. "A" gauge phone jacks. (A.P. 676). 
1,000 ohms loudspeaker. 

CR100/2 R1297 Army, RAF and other services.
As CR100 but with coaxial plug and 
(RAF) socket fittings for aerial input and with side tone facility. 

CR100/3 Superseded by CR100/5 

CR100/4 B28 W2835A

As W2835 but fitted with scale clamping device and body guard. 

CR100/5 B28 W2835B
As Patt. W2835 but with coaxial plug and socket fittings for aerial input and improved rear terminal board. 

CR100/6 B35 W8126 Admiralty.

For use with other apparatus to comprise Tuner Amplifier B.35. Special input circuits and modifications for direction finding. 

CR100/7 B28 W2835D.
As Patt W2835A but with noise limiter Admiralty Patt. 56703 and additional IF output jack. 

CR100/8 B28 W2835E.
As Patt. W2835B but with noise limiter Admiralty Patt. 56703. 

CR100/8 Ministry of Supply.

As CR100/8 except 3 ohm loudspeaker and B" gauge 
phone jacks. 
Manual and Circuit
available Details Below
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CR100 Coil Assay.jpg (28648 bytes)

The Marconi B28 CR100 Receiver Manual covers the following models
CR100 CR100/1 CR100/2 RAF 1297 CR100/3 CR100/4 CR100/5 CR100/6 CR100/7 CR100/8

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

Manual including all circuits & layouts 82 A4 pages worldwide

Printed Paper Copy or on CD are Plus Postage.

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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
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Revised: January 20, 2016