[Amps] soft start on filament

[Φραγκιαδάκης Παναγιώτης]

thank you all for the info 
now john lyles what do you  mean by magnetic design controll like the old welding machines that the core was moving manualy withe a rod ??
if so yes it will work
 peronaly i prefer a transformer with steps in primery or a varactor in primery
eny way i need 2   4 400 tubes to replace the old one if eny of you gends have some in a good shape and resnable price please let me now
god luck for the testing of the big one jhon
be very carefull of the magnetic fields arownd the big filament cables at the test 
regards panos SV4JYI