[K3PZN-List] Lightning, antennas, and coax

[Jim]

Phil 
Measuring coax impedance is very easy if you have a decent analyzer. Next this problem with an antenna being damaged by lightening when nothing hit closer than 2 miles away does not ring very true...HOWEVER, that does not mean that a good burst of static didnt wipe out something inside the tuner or radio but its not as likely as our last possibility which is I suspect this is a broken wire or poor solder joint somewhere. Just my two cents worth.. 

Finally NEVER leave your antenna hooked up to the radio when you leave the shack... even in the winter time, snow static is very dangerous and there is something as snow lightening. When you disconnect your antenna stuff it inside an old Mayonnaise jar....literally. DO NOT GROUND directly, let it float with the surroundings that way the antenna is at the same potential as everything else that surrounds it. If you tie the antenna to ground it will be ad a different potential than its surroundings and your antenna becomes a target. 

Having said all of this... opinions are like butts.. everyone has one. Thats my story and I am sticking to it. 

Jim 

----- Original Message -----

From: "Philip Karras via K3PZN-List" <k3pzn-list at mailman.qth.net> 
To: k3pzn-list at mailman.qth.net, "kyle 3599" <kyle.3599 at outlook.com> 
Cc: "Philip Karras" <ke3fl at yahoo.com> 
Sent: Friday, August 19, 2016 5:22:17 PM 
Subject: Re: [K3PZN-List] Lightning, antennas, and coax 

Kyle, 

OK, I see that Andy has taken a crack at beginning your education on impedance and I think he's done a better job than I would have done. So all I'll do it tell you to do your research on the web. Here's a good link I came across to help to learn a bit more: 

http://www.wisegeek.org/what-is-impedance.htm 

While this talks about 50 or 60 Hz remember we're dealing with anything from 1.6 to ~ 450 MHz. You're not yet dealing with stuff in the GHz range are you? 

Anyway, the bottom line is "you can't get thee from here" Meaning, you can't measure the impedance of the coax with an Ohm-meter. I believe one or both of my antenna analyzers can do this BUT, at this point in time I do not believe you need to worry about the impedance of your coax. Don't waste time trying to measure it. As long as the resistance is low for both the center wire and the shield you're probably OK. You're resistance of < 1 Ohm for the run of coax is good. 

I've never seen a coax that has changed its impedance, resistance, yes, but then I've never even tried to measure a piece of coax's impedance, has anyone? I'm not that experienced in this area, perhaps Andy has seen/done this? 

While you are at it you also need to know the difference between Watts and Volt-Amps. Yes, Volts * Amps = Watts, but in an AC circuit that has phase differences, as Andy explained about impedance due to AC voltages, Volt-Amps is a similar measure of AC Watts having phase differences. Old linear power supplies were measured only in Watts but today, with switching supplies, perhaps a better measure is the Volt-Amp - most UPS' list both the watts and the Volt-Amps they can handle. 

73 de KE3FL, 
Phil 
AEC Carroll County OES, ORS, & VEARRL Life Member 
http://cs.yrex.com/ke3fl 
Karras' Corner: http://cs.yrex.com/ke3fl/KarrasCorner.htm 



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73 de K3PZN Westminster, MD 
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