[Milsurplus] mil boat anchor sighting APN 4 in old TV show, Route 66

[Boeing377]

Lots of shots of an APN 4 Loran A set (not shown operating but all cabled up and ready to go). It is aboard the STEELHEAD, the villain's commercial salmon troller. I fished commercially during this period and used many APN 4 and APN 9 Loran A sets. They were dirt cheap and highly accurate, but needed 115 VAC @ 400 Hz and were power hogs, the 4 being more power hungry and considerably larger than the 9. 

The 9 required the operator to add 100 microseconds to the master-slave time delay reading. The 4 did not require this addition. This difference caused a few serious nav errors when the more compact 9 started replacing 4s in the fishing fleet. Tired crewmen reverted to their old training and forgot to add 100 usec.

http://www.imdb.com/title/tt0690475/

73
Mark
AF6IM