The Fernseh A.G.'s
The diode-modulator valve for the so-called Fernseh Tonne
The Fernseh AG valve type DH 7 is constitutes the diode modulator valve to the bomb-guiding TV transmitter
The here DU 10 designated valve type is most likely meant DH 7, as somewhere in the BIOS 867 file being mentioned that its reconstruction was once drawn from memory
Shown finally the modulator diode-valve type DH 7 together with the 50 W transmitter valve TU 50
I would not much wonder, when the TU 50 could be operated in the so-called Barkhausen-Kurz mode (B-K), where the anode being kept at a lower voltage against the valve grid. The voltage being chosen such, that at a certain frequency, maybe more rightly wave length, the reflected electrons will arrive on the grid again just at a 180 degrees phase-shift. Therefore, adding to the already existing energy level. This principle was especially exploited with reflex klystrons. In the latter case, the grid being constituted by a (tuned) cavity like the famous 723a and that like.
Please notice for more photographic details of the TU 50 valve