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Phone Lightning Arrestor #168985
09/23/07 10:06 AM
09/23/07 10:06 AM
Admin  Offline
OP
Administrator
Member
Joined: Oct 2000
Posts: 3,481
NY, USA
Quote
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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Re: Phone Lightning Arrestor [Re: Admin] #169005
09/23/07 02:46 PM
09/23/07 02:46 PM
N
NJwirenut  Offline
Member
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.

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

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

Member
Joined: Jul 2002
Posts: 8,231
SI,New Zealand
How does it work?

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

Re: Phone Lightning Arrestor [Re: NJwirenut] #170789
11/11/07 07:11 PM
11/11/07 07:11 PM
A
Albert  Offline
Member
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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