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## Re: [TowerTalk] Pl-259 Flash over voltage

 To: Re: [TowerTalk] Pl-259 Flash over voltage "K8RI on TowerTalk" Sat, 2 Dec 2006 00:46:06 -0500
 ``` > At 04:19 PM 12/1/2006, K8RI on TowerTalk wrote: >>The talk about breakdown voltage which is basically air across the space >>between the inner and outer conductors at the PL-259. Given LMR-400 has >>roughly 34 pfd per foot (23.9) or 230 pfd per hundred feet that is not a >>lot >>of capacity. > > Why would the capacitance for 100 ft not be 100*the C for 1 > foot? Something is weird here. Not at all. It's called short hand math. My professors had the same problem understanding it in college as you are seeing I drop the zero and you, or the reader is supposed to automatically put it back in. <:-)) I really do have a math minor. > > But, even 1000 pF or so, when charged to 10kV, can make a fairly > impressive spark. Energy = 1/2*c*V^2.. if V in kV and c in uF, then > E in joules. 50 mJoule in this case. I've been about 3 feet from a 50,000 Joul MOV when it blew. Now there's some energy. Thanks, Roger Halstead (K8RI and ARRL 40 year Life Member) N833R - World's oldest Debonair CD-2 www.rogerhalstead.com _______________________________________________ _______________________________________________ TowerTalk mailing list TowerTalk@contesting.com http://lists.contesting.com/mailman/listinfo/towertalk ```
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