21. "U-1308 " s Direction Finder Antenna Loop was located on the starboard side of the bridge. 22. The pilot instead relied on visual reference, using the copilot's automatic direction finder ( ADF ). 23. Shutting down sooner reduces the risk of the operator being found by enemy radio direction finders . 24. RU-21A's carried AN / ARD-22 direction finders . 25. Sun compasses, which use polarized light as a direction finder , are not unknown in the natural world. 26. He invented a number of other devices, including a microwave-based direction finder used during NASA's moon program. 27. The most modern equipment was sought out including the Hooven Radio Direction Finder ( licensed to Bendix ). 28. A radio direction finder ( RDF ) is a device for finding the direction to a radio source. 29. Once at Tompkinsville, the ship's crew continued training and calibrating their equipment, especially the ship's radio direction finder . 30. The associated high frequency direction finder ( HF / DF ) was carried on a short pole mainmast aft.
