Lamp; Sylvania MX-408 / U

RLBJR65 · Post by **RLBJR65** » 20 Dec 2008, 18:55

At least I think it's a lamp.
Has 2 small filaments and I lit it up (dimly) with 24vac 3, 6, 9 or 12 wouldn't light it at all. It has a Octal base is GT size and has pins at 1,2,3,5,7 and 8. Pins 2 & 7 have 12.5 ohm resistance and those light it but none of the other pins have any continuity.

I have a 49 Sylvania Technical book also googled but couldn't find anything what so ever

Anyone have the data sheet? I don't want to keep cranking up the juice until I burn it up!

Here are couple of pics.
http://sites.google.com/site/diyjunkie/ ... edirects=0
http://sites.google.com/site/diyjunkie/ ... edirects=0

You can just make out the filaments running vertically.
Taking pics of tubes is a real PITA! Must have tried 40 different ways and still had to edited the crap out of this shot.

Avatar · Post by **Avatar** » 20 Dec 2008, 19:25

Hi there,

this is a ballast tube. Here is a description of this tube type's usage: All About Ballast and Resistor Tubes.

Best regards,

Hannes

RLBJR65 · Post by **RLBJR65** » 21 Dec 2008, 01:37

Thanks! Interesting read

There is some ballast info in my technical book but nothing close to this one. Maybe my book is to new

Seems rare as no info is available. Wonder if one of the tube museums or a collector would want it?