The last post is off-topic because – as mentioned in my reply – the development of this tubes started in 1917 and took much time to develop the required process for best results. The advantage was the short connections, low height (!) and the electric shielding (net hum etc.). As a member of Radiomuseum.Org it’s quite easy to analyse the usage of this kind of tubes:

    The first available types were the E (6.3V filament serial/parallel: ECH11, …) since 1937/38, followed by D (batterie 1.2V filament serial/parallel: DCH11, …), V (50mA filament serial: VCH11, VCL11, …) and U (100mA filament serial: UCH11, …), used in car radios, portables and table radios. Not all tubes were made of steel; the power tubes (output stages, rectifiers) were made of glass in dome shape. The common sockets were equal.

    E-series:  >1000 radio models 1937/38…195x

    D-series:    88 radio models  1939/40…1952

    U-series:   679 radio models  1939 … 1952

    V-series:  143 radio models  1938 … 1951  (VF14 … 1959)

    Only ONE model (with a DDD11 tube) was no radio: a weather probe…

    All these tubes were used in radio models in following countries: Norway, Sweden, Finland, France, Austria, Switzerland, Czechoslovakia and Germany (!).

    There was NO MILITARY USE and no support/demand/whatever of any regime!

    In the USA also steel tubes were developed and used in radio models, amplifiers etc., like e.g. the 6L6 (RCA) since 1936, 6AG7 since 1939 and the Russian tubes like the 6П9 since 1946. These are only samples for hundreds ore mode other (similar) types.

    In USA proofed tubes with certain characteristics were certified with “JAN” (Jointed Army / Navy).

    In Great Britain quite similar (tubes and semiconductors). stamped as “CV…” types.

    In Germany until 1945 the military tubes/valves started with: LB /LD /LG /LK /LS /LV (L=Airforce), and RD /RG /RK /RL / RV (R=Army).


    • This reply was modified 4 years, 5 months ago by Guenther.
    • This reply was modified 4 years, 5 months ago by Guenther.