Predicta Holiday restoration

[bandersen]

I checked the filament current when the set is turned on and found it peaked at about 1 amp then settled down to 600mA after 10 seconds. That's with a single CL-90 (120 ohms cold) in place of the original thermistor (400 ohms cold).

I then tried it with two CL-90s in series and got a peak or around 850mA before settling down to 580mA.

I checked in my RCA tube manual but couldn't find any data about permissible cold filament startup currents.

Does anyone know if it's OK to have 1A (or more) running through a 600mA tube for a few seconds every time a set is turned on ?

If not, I could go with three CL-90s in series to really keep that current surge down.