CR-100 Series of Receivers
This is a superheterodyne receiver with low frequency coverage from 60 to 420 KHz and  medium/high frequency coverage of 500 KHz  to 30 MHz. The IF passband can be varied from 6000 Hz  to 100 Hz. CR100 receivers designed to British Admiraly specs were given Bxx designators,

Power input - 200/250 VAC, 50 Hz @ 85 watts or 6volt nd 160VDC.
Weight - 82 pounds.
Dimensions in inches - 16W x 16.5D x 12.5H
Vintage: First version 1940. Fred Osternam's book shows 1944 to1945 for CR100/7 series..


Marconi   Service Type   Patt. No             Details
Type No.     No.
CR100       ---                   ---         Prototype. Low phone level. Used "B" gauge phone jacks.
                                                        3 ohm loud speaker.

CR100/1     B28            W2835      Admiralty. Pattern High phone level. "A" gauge phone jacks. (A.P
                                                      . 676). 1,000 ohms loudspeaker. Circa 1940

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CR100/3     ---                ---           Superseded by CR100/5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.
                                                        Circa 1941

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

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. 

Internal view of CR100 receiver (Photo by Jason Ingraham, VE1PYE)
Contributors and Credits:

1)  Marconi Manual T1868
2) Jason Ingraham, VE1PYE  <the_doctor31(at)>
3) Shortwave Receivers Past & Present Communications Receivers 1942-1997 by Fred Osterman.
4) Sandy Blaize ebjr37(at)

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Nov 8/12