Radio Operator's Information File KC-135 The indicator is also marked

The indicator is also marked with K

and P-47 Thunderbolt

It included a toggle in the center to test that the bulbs were good

This Cold War / Vietnam War era Radio Magnetic Indicator (RMI) ID 250/ARN was made by Bendix for use in aircraft of the US military in the 1950/60's and used in the AN/ARN-14 Radio Navigational System (see illustrations)

After winding

Radio Operator's Information File KC-135 The indicator is also markedThis is an original WWII era Radio Operator's Information File published in 1944 (updated 1945) by the US Army Air Force. It is the basic reference book for aircraft radio operators in the performance of their duties. See photos. The page numbers are by section, so total pages are not estimated here. It is about 1 2 inch thick. All pages are intact as is the soft cover. It is in exceptional condition given its age.