Type: Whereas the DF types 11A and 11B  are intended for use with an open Marconi-Bellini-Tosi aerial system, the type 11F D.F. has been designed for use in conjuncion with a fixed frame aerial.
Frequency Range: 300 to 4,800 meters
Valve lineup:  Six DEV or V24 valves and one DEQ or QX valve.

11F Direction Finding Set. (Source unknown at this time)

11F schematic. Download to enlarge. (Courtesy Wireless Telegraphists)

 
Contributors and Credits:

1)  Lewis Bodkin  <05bodkin555(at)gmail.com>
2) "The Handbook of Technical Instruction For Wireless Telegraphists", Fourth edition. 1929

 Apr 15/20