The 1698 is a two inch monoscope. Essentially an electrostatically deflected CRT with a target electrode rather than a screen. The built-in pattern is scanned and the output is a video voltage of the design. The details of the pattern produced can be found within the attached PDF.
The tube came in fabric bag with a copper interior, presumably to provide electrostatic protection as well as excluding ambient light in transit.
The RCA branding on the base cap.
The pattern electrode and target.
The target connection.
The base: the pins look unused.
The gun assembly and the pressed glass foot.
An enhanced look at the glass foot.
Looking towards the deflection plates.
The wide glass tube envelope is 50 mm in diameter and, excluding the B14A base pins, is 205 mm tall.
References: Data-sheet, Lamps and Tubes. Type 1698 was first introduced in 1950. See also1950 adverts.
