But a direction finder could have betrayed his position.
"Operation Terror" by William Fitzgerald Jenkins
Inside the rifle was a tiny radar direction finder.
"On the Trail of the Space Pirates" by Carey Rockwell
The birds had had their direction-finders attuned to it, long before there was man.
"Sense from Thought Divide" by Mark Irvin Clifton
Like a sonic direction finder, Buregarde turned his head and listened.
"History Repeats" by George Oliver Smith
Even their worn-out direction and distance finders could place the ten or so voices as originating not much over a hundred miles away.
"The Planet Strappers" by Raymond Zinke Gallun
Only half of Jason's mind was occupied with the work as he drew up a list of materials he would need for the psionic direction finder.
"Deathworld" by Harry Harrison
For the graphs of the radio direction-finders showed a curve.
"Astounding Stories, June, 1931" by Various