*The Lo40K39d comes in two parts.  The power supply is on the top, and the transmitter is on the bottom in this photograph.
*The d version operated approximately in the 20 meter to 80 meter bands (3.0-16.667 mc/s).
*It had a frequency accuracy of plus or minus 1-2% (+/-  3-x-106).
*In the type VII/C U-boats, the transmitter was kept in the listening/sound room.  In the type XXI boats, it was located in the radio room.
*The Lo40K39C transmitted in Morse Code only; it could not make voice transmissions.
*It was often paired with the Radione R3 receiver.

Photo by Bruce Culp
Photo by permission of the Stg.C.D.V.&.T.