B-3 Privacy Unit/Speech Scrambler

Type: Privacy equipment
Made by: Western Electric
Date codes on components: Range from Jan 1941 to March 1941. Manuals are  dated 1944.
Manual reference: TM 11-383   Technical notes on the B3 Privacy Unit here.
Misc. info: The Library of Congress has a book from NDRC Vol 3 1946  titled "Speech and Facsimile Scrambling and Decoding. Pg. 40 calls the B-3 scramble system a "Double Modulated wobble band displacement " that has no synchronizing pulse to crack. Pg. 47 mentions it is double modulated. One web reference indicates thet the CV46/FR converter is used with the B3.

There is no other information available for this device at this time. If you can contribute, please contact: jerry.proc@sympatico.ca

B3 - General view of the B3 device . It has swinging doors on both the front and back. 
B3 - A detailed view of the front. A small piece of paper found on the inside, said it was a speech scrambler used for Green Harbor - P'Town link during WW2. P'Town is slang for Provincetown, MA. Note the jack field at the left side of the chassis. Jumpers plugged into this jack field may have determined the method of scrambling. 
B3 - Rear view. There are tags that read: Green Harbor, input receive privacy, output receive privacy, transmit privacy input and transmit privacy output. One tag is marked "record" while another  denotes "to O control".
B3 - Rear view.  Both the front and rear are  rubber stamped as "B-3 PRIVACY". One side of the cabinet  has a Western Electric 2-A cabinet tag.
This B3 rubber stamp marking designates the model number. It is not known if there was an actual nameplate affixed to the chassis or cabinet. 
All photos in this table by Robert White

Contributors and Credits:

1) Robert White <19nonni62(at)gmail.com>
2) http://www.radiomanual.info/schemi/Surplus_Handbooks/Old_US_army_technical_manuals_TM11_list_PAM310-4_1955.pdf
3) Steve Rosenfeld <oceangate(at)comcast.net>

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May 24/18