Bottlehead Forum

Bottlehead Kits => Crack => Topic started by: Nathan on January 27, 2015, 07:59:25 AM

Title: Discolored getter on a NOS tube
Post by: Nathan on January 27, 2015, 07:59:25 AM

Recently bought a NOS CV4003. When it arrived (very recently) the getter was shiny silver. I now find it is blotchy, partly silver, and partly brown/black. I bought from a reputable seller and sent the seller a note about this.

Can anyone tell me if this discoloration is OK or a sign of impending issues?

Everything sounds ok-

Title: Re: Discolored getter on a NOS tube
Post by: Paul Birkeland on January 27, 2015, 08:08:30 AM

As long as it isn't white, there isn't anything to worry about.

-PB

Title: Re: Discolored getter on a NOS tube
Post by: Nathan on January 27, 2015, 08:10:22 AM

White = Bad, as in gassed out

I knew that- thanks!

Title: Re: Discolored getter on a NOS tube
Post by: Doc B. on January 27, 2015, 09:31:33 AM

Yeah, what you are seeing is a getter that did it's job. There was some gas in the tube and the now brown area is where the getter flashing reacted with it to clear it from the tube.

Title: Re: Discolored getter on a NOS tube
Post by: Nathan on January 27, 2015, 10:00:35 AM

Could that be indicate of a tiny leak?

Title: Re: Discolored getter on a NOS tube
Post by: Doc B. on January 27, 2015, 10:17:46 AM

Nope, a real leak equals a white getter. It just had a little residual gas that is now taken care of. If the tube sat for 30 to 50 years, perhaps the gas slowly got in thru the pin seals. Or it could just have been a contaiminant in or on one of the inner structures that slowly outgassed over that time span. Either way the amount was insignificant as there is still plenty of getter left.

Title: Re: Discolored getter on a NOS tube
Post by: Nathan on January 27, 2015, 10:24:06 AM

Doc- thank you!

PS- I beleive the tube is over 30 years old