Radio operator
The radio operator could send diving reports, safety messages and
intelligence reports when the
HF antenna could be hoisted above
the surface.
When submerged he could only receive very low frequency signals VLF down to 30 m depth. In such cases the submarine was only receiving signals and the radio operator couldn't acknowledges the signal.
Most of the traffic was encrypted telegraphy in the high frequency band, 3-30 MHz, utilising two HF receivers and a 50 W
HF transmitter. The boat also had a radio station operating in the VHF band to be used as
short distance
telephone when on surface.
You can here listen to
typical encrypted radio message!
Here follows an
explanation
on the sample.
Two radio operators served, ships number 53 and 54, and they had to work
on a two watch system.
Besides the duty in radio communications they handled the mail and some office duty. It was a welcome task to go ashore to see the post office.
U3 Direction finding receiver, HF antenna tuning box, antenna switch and the VLF receiver. Photo U3 archives.
U3 Two HF receivers and the telegraph key. Right the HF transmitter. Photo U3 archives
Tuning the HF receiver. Photo U3 archives.