[K3PZN-List] Lightning, antennas, and coax

Sun Aug 21 17:10:22 EDT 2016

Jim,
There's only one thing I disagree with, and this comes from my physics background & reading about lightning rods.
The object of lightning rods is to dissipate the surrounding static electricity charge building up around a building.To do this they tie the lightning rods to two or more grounding rods around the building. The way the rods on the roof dissipate the charge building up around the building before it gets so high that it produces a lightning "strike" is that the charge follows the wires up to the points on the lightning rods and as the wind blows by it takes the charge away, thus rendering the building area less charged and less likely to attract the opposite charge from the clouds as a lightning bolt.
If we understand this correctly then if we tie any antenna to ground, because ALL antennas have at least one point, then all points on the antenna will act as lightning rod points and help dissipate the charge building up around our house and make it less likely that a lightning strike will occur.
So, I disagree with you saying you should not tie your antenna to ground, I say tie all antennas, and both sides of all antennas, to a good ground rod used for grounding your station so that any charge build up in that area will be dissipated by the points on your antenna and help reduce the likelihood of a lightning strike.
That's my analysis and story and I'm sticking to it like a good ground connection too ;)

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

      From: Philip Karras <ke3fl at yahoo.com>
 To: Jim <wa3mej at comcast.net> 
Cc: "kyle.3599 at outlook.com" <kyle.3599 at outlook.com>
 Sent: Sunday, August 21, 2016 4:48 PM
 Subject: Re: [K3PZN-List] Lightning, antennas, and coax

Jim,
You and I are on the same page here, I was giving the same advice to the young ham, Kyle, who asked the question and was trying to measure impedance with an ohm-meter.
I too suspect a cold solder connection or an intermittent/broken connection.
I've copied Kyle on this email so he too will have your ideas.

Tnx & 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

      From: Jim <wa3mej at comcast.net>
 To: Philip Karras <ke3fl at yahoo.com>; List-K3PZN <k3pzn-list at mailman.qth.net> 
 Sent: Friday, August 19, 2016 11:00 PM
 Subject: Re: [K3PZN-List] Lightning, antennas, and coax

PhilMeasuring 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
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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