Hello Mr. Tore,
Echolot info taken from the German Type VIIC training manual...
"Each device consists of: transmitter, receiver and amplifier. The shallow depth sounding device works noiselessly, while the deep depth device sends sound impulses which are audible. Both devices are powered by the AC shallow and deep depth echo sounding converter located in the E-motor room.
The deep depth sounding device has three transmitters and three receivers which are mounted in the keel. The shallow depth sounding device has one transmitter and one receiver. Both are mounted on bottom of the hull, on the port side, near the munitions magazine."
Regards,
Don_