NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Radio direction-finders
From: Joe Schultz
Date: 2009 Dec 9, 07:52 -0800
From: Joe Schultz
Date: 2009 Dec 9, 07:52 -0800
My first exposure to RDF was as a kid, on Puget Sound fishing boats. It was fun to visit a "rich guy's" boat and watch their ADF hunt around, then lock in. The older sets (ca.1950s - 1960s) had an antenna attenuator, just like the old house radios (ca.1930s), and that worked very well on the short range stuff that we did for real, just like George's excellent real-life story. Those older RDF radios may not have had AGC; I can't remember. Fun was changing a tube when the boat's slamming. Also played RDF in the Navy, as an emergency backup on the AM(MW) band with a portable radio. One commanding officer was not amused. "What's a radio doing on my bridge?! And why did you change course?!" "Training in radio direction finding, sir." "With a RADIO?!" "Yes sir. Rrradio direction finding." "Oh. Come see me after your watch." A five degree course change woke him. Somebody (I'm not saying who) forgot to shut the lid on the voice tube to his cabin, and he heard the music. After that episode the training was off watch, on the signal bridge. I still practice RDF'ing on the AM(MW) band, which is a different ballgame than the old LW stuff, especially on the new radios with phase lock loop (PLL) tuning. Good to 1000 miles on inexpensive equipment. If folks are interested then I can do a short writeup, showing how I build an antenna database, the bearing conversion calculations, and building a Mercator plot. You can get pretty good at it in a short period of time. Question for George: is navigation RDF still in use in Europe? I'm talking about the LW frequencies (under 530kHz). Over here it's dead as of next year; the fishermen's politicians couldn't keep it going. Joe -- NavList message boards: www.fer3.com/arc Or post by email to: NavList@fer3.com To , email NavList+@fer3.com