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[AMPS] gettering

To: <>
Subject: [AMPS] gettering
From: (2)
Date: Thu, 13 Sep 2001 19:32:35 -0700
>> >//   Where is the getter in a 3-500Z?
>> >Where is the getter in an 8877?
>> >Can gettering take place while a tube is cold?
>This has been covered a dozen times on this reflector.
//  I heard about the getter in a 3-500z on AMPS, but I do not recall 
seeing any info about a 8877 getter.

>The 3-500 gettering agent is zirconium, the gray powder-looking 
>coating on the anode. It is sprayed on, and activates at about 1000 
>degrees C. In the ideal case it should run at various temperatures, 
>because the gas liberated at one temperature is absorbed at 
// 1000º C is yellow/white-hot.  If  this were the case, gettering would 
not take place.

>The 8877 uses tantalum. It is mounted near the cathode and 
>heated to temperature by the heater.  This was one source of 
>chronic 8877 failures in the 80's, because the cathode was moving 
>when the tantalum was warping.
>All getters outgas to some extent, as do other  elements in the 
>Arcs also getter the tubes, by causing a plasma that breaks-down 
>the gas into harmless elements that bond to material in the tube. 
>As a matter of fact, some tubes are (or used to be) gettered during 
>manufacture with intentional internal arcs. 
>> I recommend contacting the manufacturer for these questions. If you
>> prefer to avoid Eimac, then talk to Claude Peterson at Econco in
>> Woodland, CA. (800) 532 6626. He was involved with some of the glass
>> Eimac tubes at Salt Lake City before they sold that operation. Maybe
>> the 3CX1500A7/8877 as well.... Let us all know what you find out.
>Why depend on someone else to accurately convey what is told? 
//  Amen, Mr. Rauch.  This why I did not accept the claim that the 3-500Z 
was rated at 500mA.  This is why I telephoned Eimac about the alleged R&D 
Engineering Manager who proved to be as phony as a $3 dollar bill.$3.JPG

>Rather than take second-hand info, you can find books on the 
>subject. There are entire chapters on gettering.
//  Books contain second hand, third hand, and fourth hand info. 

>Try the Electronic Designers Handbook and other detailed 
>engineering books. Eimac mailed me 19 pages of information in 
>1982 titled "Getters and Their Function in Vacuum Tube 
>They also mailed info on neutralizing grounded grid tubes. Rich 
>may have copies of both that he hasn't read yet. 

//  chortle

---  But alas, no answer to the question:  Can gettering take place while 
a tube is cold?
-  My guess is that Mr. Rauch knows that if he grasps this hot potato, 
someone is quite likely to quote from Will Angenent's Grate Parasitics 
Debate archive.  

cheers,  Tom Rauch

-  R. L. Measures, 805.386.3734, AG6K,  

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