S 406 Technical Page 1
Directly to the left of the door to the radio room, mounted
on the table, is the high-frequency transmitter. It is a Telefunken type S406S2/36. The frequency range is 20 to 80 meters in ten steps.
The cabinet is twenty inches wide,
thirty-one inches high, and eighteen inches deep. The left hand side of the unit is accessible through a hinged door. The panel must be removed to obtain entrance to the right hand side. With the door open and the panel removed, there is a large ceramic housing
containing the band switch and master oscillator tuning assembly. Two Telefunken REN904 tubes are mounted in this unit. There is about four inches between the master oscillator housing and the edge of the cabinet. In this area are mounted two RS288 pentodes
in an inverted position. These are connected in parallel and are presumably the buffer amplifiers. Directly above these tubes are mounted the final amplifiers, consisting of two Telefunken RS291 triodes connected in parallel. These tubes are the same as those
used in the low-frequency transmitter and are rather good looking, straight tubes about ten inches high, with slightly oval plate construction. Two fairly large cooling fins project from each side of the plate and are connected to the plate lead at the top
of the tube. Parasitic suppressors are built in and are a part of the plate connectors. To the right of these tubes is the antenna tuning unit, self-contained in a casting that occupies the entire upper right-hand corner of the cabinet. There are two meters
in this unit: the antenna current meter and the plate current meter for the final amplifier stage. No coils are visible. The transmitter is divided into two parts with the tubes in the front and the coils in the rear. Directly in the center of the transmitter
is a small full-wave rectifier which furnishes power to the master oscillator and fixed bias to final amplifier stage.