[Milsurplus] LO radiation

[Hue Miller]

To clarify so far, i assume this particular discussion is about WW2.
( Altho the Tempest bizness is interesting. )

I'd suggest that a U-boat running surfaced, would have two receivers
ready, one on the fleet broadcast frequency, for late-breaking 
messages about target locations, and one on 500 kHz, for listening
for SSS and SOS messages from enemy ships.
There is a German book, "Feind im Fadenkreuz",  ( "Enemy in the
Cross Hair" or "Enemy in the Target Sight" ) 1942, which has 
accounts of sinkings in the "good old days" for the U-boats.
The U-boat at least at the point of attack was listening on 500 kHz.
I recall one recount where the U-boat captain demanded from the
freighter captain, in a lifeboat, why an SOS was sent, after the U-boat
had warned not to send.  ( This was in the early days, when a sub
(in the European theater) could still surfaced challenge a ship  and
demand it stop. -Hue Miller