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512-620-400 i5 Apr64 - Speakerphone System 3 - Control Units - Excerpts Tl

Issue 5, April 1964. Includes BSP pages 1,2,3,5 and 6 of 12 pages. Page 5 is a schematic of the 55B Control Unit, and is scanned on two pages (left and right of the sheet) and is the last two pages of the document.  Page 6 is a schematic diagrams for the 666A Transmitter.

Does not include pages detailing the 55A Control Unit, 666B, 667-type, 669A, 670A and 671A Transmitters.

(Probably scanned to support a Listserv discussion on the components shown.  We hope someone will scan and contribute the full BSP.)

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