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New tool
by SMOKEYBOB - 02/15/21 04:59 PM
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0 registered members (),
14
guests, and 19
spiders. |
Key:
Admin,
Global Mod,
Mod
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Phone Lightning Arrestor
#168985
09/23/07 10:06 AM
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Joined: Oct 2000
Posts: 3,636
OP
Administrator Member
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Re: Phone Lightning Arrestor
[Re: Admin]
#169005
09/23/07 02:46 PM
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Joined: Sep 2001
Posts: 806
Member
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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.
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Re: Phone Lightning Arrestor
[Re: NJwirenut]
#169007
09/23/07 02:50 PM
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Joined: Jan 2005
Posts: 5,316
Cat Servant Member
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Kryptonite? I feel weak .... 
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Re: Phone Lightning Arrestor
[Re: Trumpy]
#169442
10/05/07 06:23 AM
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Joined: Sep 2001
Posts: 806
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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.
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Re: Phone Lightning Arrestor
[Re: NJwirenut]
#170789
11/11/07 07:11 PM
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Joined: Aug 2006
Posts: 81
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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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