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#168985 - 09/23/07 08:06 AM Phone Lightning Arrestor
Webmaster Offline


Registered: 10/07/00
Posts: 3142
Loc: NY, USA
I found this in an old sewage pumping station contol panel. It's from the mid 70's. Enjoy!

- Pappster855 (Ian)

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#169005 - 09/23/07 12:46 PM Re: Phone Lightning Arrestor [Re: Webmaster]
NJwirenut Offline

Registered: 09/15/01
Posts: 816
Loc: 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 12:50 PM Re: Phone Lightning Arrestor [Re: NJwirenut]
renosteinke Offline
Cat Servant

Registered: 01/22/05
Posts: 5305
Loc: Blue Collar Country
Kryptonite? I feel weak .... \:D

#169426 - 10/04/07 05:39 PM Re: Phone Lightning Arrestor [Re: renosteinke]
Trumpy Offline


Registered: 07/05/02
Posts: 8532
Loc: SI,New Zealand
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 04:23 AM Re: Phone Lightning Arrestor [Re: Trumpy]
NJwirenut Offline

Registered: 09/15/01
Posts: 816
Loc: 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 04:11 PM Re: Phone Lightning Arrestor [Re: NJwirenut]
Albert Offline

Registered: 08/16/06
Posts: 76
Loc: Falls Church, VA
And I believe the "7448" marking is a date code, indicating the tube was manufactured in the 48th week of 1974.



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