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Phone Lightning Arrestor #168985 09/23/07 10:06 AM
Joined: Oct 2000
Posts: 3,636
Admin Offline OP
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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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[Linked Image]

[Linked Image]

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Re: Phone Lightning Arrestor [Re: Admin] #169005 09/23/07 02:46 PM
Joined: Sep 2001
Posts: 806
N
NJwirenut Offline
Member
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.

Re: Phone Lightning Arrestor [Re: NJwirenut] #169007 09/23/07 02:50 PM
Joined: Jan 2005
Posts: 5,316
renosteinke Offline
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Kryptonite? I feel weak .... laugh

Re: Phone Lightning Arrestor [Re: renosteinke] #169426 10/04/07 07:39 PM
Joined: Jul 2002
Posts: 8,379
Trumpy Offline
Member
How does it work?

Re: Phone Lightning Arrestor [Re: Trumpy] #169442 10/05/07 06:23 AM
Joined: Sep 2001
Posts: 806
N
NJwirenut Offline
Member
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.

Re: Phone Lightning Arrestor [Re: NJwirenut] #170789 11/11/07 07:11 PM
Joined: Aug 2006
Posts: 81
A
Albert Offline
Member
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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