Hal Roth reportedly used a Radio Shack transistor AM radio and commercial radio
stations to navigate, and Hal Roth is just over 80 now.

but yes, by the 1960's RDF through commercial AM radio stations was less
accurate that purpose-build, accurately placed AM nav radio stations.

I believe Loran-A dates from the late 1940's.

Although I can't speak for the years prior to the 1960's, no self
respecting navigator I knew after that time would use any AM radio
station for navigation, unless all else failed.
Two major problems .... the signal could be "bent" traveling over land,
then water (hence the reason most marine RDF stations were at
lighthouses, or close to the shore) and the locations of the radio
towers for AM stations were not always on the charts in use or denoted
(I don't have a 117 here to see if some may have been listed).
Also, I'm not sure, but I think the calibration error on the particular
Shipboard RDF, was done for the relatively narrow band used by RDF
stations (not necessarily true throughout the history of RDF).

otn

JAXAshby wrote:
I was writing of your plain vanilla AM radio stations, such as KRLA, KSTP,
WCCO, WABC, etc. Marine RDF stations were stations operated (by I believe
in
the US by the CG and FAA) specifically for ships at sea and later aircraft.

Best of my knowledge marine RDF stations operated in th same frequency
range as
commercial AM radio stations.


Are you talking about radio stations such as ABC in New York, or Marine
Radio Beacons?
Marine Radio Beacons are a different animal, though agreeably obsolete.
However, they are still (RDF) to be found on ships.

otn