Original Marconi DSB (DS)

screen grid tetrode

antique radio tube
this is the first version of a very rare tube with
Europe 5-Pin (O5A, B5) base and top contact screw type
the tube tests strong  - 100%
Ia = 3,4mA
where 3,4mA is 100% for the new tube

f=16V; Ua=150V; Ug2=90V; -Ug1=1V

There is a possibility that the tube were never used, just stored for more than 80 years
you will surely need this tube to restore antique British and Belgian radios from 1930's
you will get the tube you can see at the pictures.
I always send the tubes by priority registered mail with tracking number within hours after receiving payment

                                                                                                                                                      Ivette