Portable Spark Gap Transmitter - Type 11982

Purpose: Portable spark gap transmitter used in WWI era aircraft.
Manufacturer: Marconi Wireless Company of Canada
Model : 11982     S/N 1
Power input:  External battery.
Circa : Believed to be 1918 . The Marconi Wireless Company of Canada operated under that name between 1905 and 1925, After 1925, the company was renamed to Canadian Marconi.

The black Bakelite scale at the 7 o'clock position has the following markings: 100, 125,150, 175, 200 and 250.  These are believed to be in meters. Selecting a particular position on the coil determined the operating frequency.
 The black object on the interior left side is a Rolled Condenser. It was made by the Northern Electric Company Ltd. and Patented in 1905. The capacity, in M.F., is illegible on the hi res photos but it's a Type 21(?) with an illegible variant. 
This view shows the under panel wiring. At the right side is the vibrator adjustment for the internal spark coil. 
All photos in this table by Tim J Patton, K4TJP.

In contrast, the SCR-65 (circa 1918), a quenched gap spark transmitter, was used in WWI era aircraft. It was manufactured for the United States Signal Corps and was also designated as the BC-15. (Photo courtesy radiomuseum.org) 

Contributors and Credits:

1) Tim J Patton K4TJP <tjpatton44(at)gmail.com>
2) SCR-65 photo     http://www.radiomuseum.org/r/connecticu_airplane_radio_telegraph.html
3) Richard Dillman <ddillman(at)igc.org>
4) Will, W0EOM(at)aol.com

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May 20/11