Blue Arcturus type 124

First it was internal shields deposited on the glass. Then it became artistic, hiding the innards of the tube. I didn't know they used colors tho. I think the Russian tubes were the first to coat the inside for aesthetics.

Cheers

Cheers

Getters? They were functional.

No, not a getter.

I haven't seen that. Got a picture?

The Arcturus tubes were just made of blue glass.

For some reasons, some big transmitting tubes had no obvious getter.

Getter is conductive, so it might cause problems when there are huge rf fields. There are getter systems that use a reactive pellet welded to an internal structure rather than the getter being evaporated onto the glass.

John

The pellet is a barium-aluminum alloy that's pretty stable in room air but outgasses Ba when heated. That's how they deposit the getter after the tube is pumped out.

Cheers

Phil Hobbs

Having trouble finding datasheet for that exact tube, I guess it's an early # 24 tetrode?

The type was used as the first stage in the Loftin-White amplifier around 1930, the first big improvement over transformer coupled audio amps for cost/weight reduction. DC feedback applied to the screen grid to stabilize the operating point, to allow direct coupling: