RADIO DIRECTION FINDER
The one we used in the 60''s picked up stations broadcasting dots and dashes, a unique morse code for each station. I found it extemely difficult to identify the stations, ie to decipher the dits and dahs. But once I was sure I had the right station it was easy to locate its direction by rotating the dial untill I could no longer hear it ( called finding the "null" I beleive) and then reading the compass rose on the RDF. We used to place the RDF on the main hatch and turn it so it was lined up with the direction we were going. We were not very good at triangulating a position and considered 1 mile good. What the RDF proved fantastic for was in hunting down a signal such as Minneapolis Shoal in a dense fog. The closer one gets to the signal the more accurate your course becomes and I guarantee you if you don''t keep a watchfull eye out you will run right into it. I must confess that in the early 60''s we were not very good at navigation so others may have an entirely different view. I would like an RDF as a backup in case GPS ever went down.