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Microphone Documentation & Pictures:

Microphone Pages from the 1955 RCA Broadcast Equipment Catalog:
 Page One - Intro - Mic Types & Application
 Page Two - Intro
 Page Three - 44-BX
 Page Four - 44-BX
 Page Five - 77-D
 Page Six - 77-D
 Page Seven - 77-DX
 Page Eight - 77-DX
 Page Nine - BK-1A
 Page 10 - BK-1A
 Page 11 - BK-4B
 Page 12 - BK-4B
 Page 13 - BK-5A
 Page 14 - BK-5A
 Page 15 - BK-6A
 Page 16 - BK-6A
 Page 17 - SK-35
 Page 18 - SK-35
 Page 19 - SK-45
 Page 20 - SK-45
 Page 21 - SK-46
 Page 22 - SK-46
 Page 23 - MI-12016H (dynamic)

RCA 1962 Catalog:
 BK-11A, page one
 BK-11A, page two

RCA 1974 Catalog:
 LC-9 Horn Speaker System
 RT-21B Open Reel Recorder, page one
 RT-21B, page two

Photos regarding the custom order of a Western Electric 640AA condenser microphone system, with customised General Radio preamp & Bruel & Kjer power supply, by J.R. Sank, while at RCA:
 Photo of 640AA capsules
 Photo of 640AA with G.R. preamp in RCA Camden's anechoic chamber, in front of Harry F. Olson's precision sound source

Link to Jim Steele's Vintage Broadcast Microphones site, which has a wealth of other RCA info:
 Vintage Broadcast Microphones

Bang & Olufsen Ribbon Microphone Data Sheets:
 Mono BM-3 - aka Dynaco/Fen-Tone 50
 Mono BM-4 - aka Dynaco/Fen-Tone 53
 Stereo BM-5 Blumlein Crossed Figure-8 - aka Dynaco 100
 Mono BM-6 - Bottom half of BM-5
 Mono BM-7 Module - Top Half of BM-5
Any of the B&O ribbon mics, including pre-BM-3 mics not listed here, can be "BX mod'd".  This is my nickname for the installation of a modified RCA 44-BX ribbon element.  For about $150 per mic element, these become so close to the real 44-BX in performance that it is absolutely astonishing.  See the mic service/restoration page for more on this.