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#168985 - 09/23/07 11:06 AM Phone Lightning Arrestor  
Admin  Offline

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Joined: Oct 2000
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Quote
I found this in an old sewage pumping station contol panel. It's from the mid 70's. Enjoy!

- Pappster855 (Ian)

[Linked Image]

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#169005 - 09/23/07 03:46 PM Re: Phone Lightning Arrestor [Re: Admin]  
NJwirenut  Offline
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Joined: Sep 2001
Posts: 806
Bergen County, NJ
Yeah, those are neat looking things. I have one of them in my tube collection. Yours apparently took very few "hits" over the years, as the glass isn't blackened and the graphite balls look to be in good shape.

BTW, the "KR-85" marking on the base refers to Krypton-85, a radioactive gas. The tube contains a small amount in order to stabilize the triggering voltage. No hazard at all in a sealed tube, but if it breaks, open the window and air out the room.


#169007 - 09/23/07 03:50 PM Re: Phone Lightning Arrestor [Re: NJwirenut]  
renosteinke  Offline
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Posts: 5,316
Blue Collar Country
Kryptonite? I feel weak .... laugh


#169426 - 10/04/07 08:39 PM Re: Phone Lightning Arrestor [Re: renosteinke]  
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How does it work?


Let's face it, these days if you're not young, you're old - Red Green grin

#169442 - 10/05/07 07:23 AM Re: Phone Lightning Arrestor [Re: Trumpy]  
NJwirenut  Offline
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Joined: Sep 2001
Posts: 806
Bergen County, NJ
3 separate graphite balls in an inert gas atmosphere (Ar+ Kr-85). 1 ball is grounded, and the other 2 connect to the lines being protected.

Under normal conditions, the tube does nothing, but if the voltage on either of the protected lines exceeds a certain value (~150V, IIRC), the gas ionizes, and effectively shorts the line to ground. Once the overvoltage goes away, the gas de-ionizes, and waits for the next surge to come along.


#170789 - 11/11/07 08:11 PM Re: Phone Lightning Arrestor [Re: NJwirenut]  
Albert  Offline
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Joined: Aug 2006
Posts: 76
Falls Church, VA
And I believe the "7448" marking is a date code, indicating the tube was manufactured in the 48th week of 1974.

Albert



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