strange tube G1 S/5

[Mr. Triatic]

Any ideas what kind of tube this is?

Made by "Standard radiofabrik" in Sweden
Printed on the carton: G1 S/5

size about the standard, 6AS7 and like..

 

[poobah]

Looks like a light bulb - 😀

 

[Mr. Triatic]

are you really sure?

seriously, of course it can be just a lightbulb, but why are there something like a getter-plate connected to one of the pins?
I was thinking it was a "slow-start" kind of gizmo or a series-filament-thingie..

 

[Giaime]

Mmm... some ballast kind of thing, or even a very strange gas tube if you say it has a plate... however, from the photo, no signs of getter or plates.

Have you tried to light it up? Maybe firstly measure DC resistance of the filament, just to make a rought guess on what voltage this is supposed to run.

 

[poobah]

NO... I am just joking. But now I am looking...

😀 😀

 

[Mr. Triatic]

DC-resistance is merely 4 ohms between pin 2 and 7..

 

[poobah]

It may very well be used for signal compression. Used in the same incandescent bulbs are/were.

Perhaps for gain control in early radio recievers ot transmitters as well.

Just guessing...

 

[Mr. Triatic]

detail..

 

[Mr. Triatic]

due to the particular use of pin 2 and 7, can it just be a "dummy-load" for a series-filament tube, during faultfinding?

 

[poobah]

That is a very good guess...

 

[poobah]

Is the pin running down the center a conductor?

Is the center pin connected to an external base/socket pin?

Is the donut in the center (around the pin) an insulator?

What type of base for the tube?

 

[DigitalJunkie]

I suspect it's some type of ballast tube,but I could be wrong.. 😀

 

[rpapps]

The word "baretter" popped into my head.
But I can't remember what they were used for.
Cheers
Rob

 

[Geek]

Stabilization, IIRC. Sort of like what a light bulb does in a Wein bridge...

 

[billr]

I think that it is a barreter, can't even remember if that is how they are spelt.

I used to be a technician in British Telecom many moons ago, and when I was an apprentice we used to have to change the things.

They were used as current limiters in subs circuits. They are basically light bulbs.

hope that helps.

bill

 

[thevoice]

It looks like a barreter to me too. I have an AC/DC Phillips radio that was wired by a madman that uses one. It performs current limiting for the series filament circuit, necessary because of the wide range of voltages the thing may get plugged into.

It has no transformer you know, a live chassis. They don't do things like that anymore...

 

[Mr. Triatic]

shall we say that concludes it?, its a baretter..

rather worthless thingie in my amps, but hey, its a beauty on the bookshelf 😎

Thank you guys!

 

[EC8010]

I think it looks like a barretter (two "t"s). As previously mentioned in this thread, they were used in telegraph circuits as short-circuit protection and glowed like lightbulbs when driven into a short-circuit. The difference between them and a lightbulb is that instead of the bulb being evacuated, it's filled with nitrogen. The other use of their non-linear resistance was in series heater chains to keep the current constant.

I have a few flimsier versions and hadn't previously seen such a beefy example.

 

[adalin]

I got a variety of different models in my stock, I have seen them in some old radios and stuff, used for regulation and ballast I think.

I got models from 90v up to 220v some big and some small

 

[jlsem]

The difference between them and a lightbulb is that instead of the bulb being evacuated, it's filled with nitrogen.

Here in the United States, ballast tubes (barretters) are filled with either hydrogen or helium and are used as current and voltage regulators. They are still available from Amperite. Light bulbs here are generally filled with a noble gas under low pressure, so the main difference between the two is that the ballast tube generally has a higher resistance filiment and doesn't glow as brightly.

John