Topband: A Bit Off Topic

[Charles Cu nningham]

Thanks!

 

From: Mike Waters [mailto:mikewate at gmail.com] 
Sent: Saturday, June 27, 2015 6:20 PM
To: Charles Cunningham
Cc: topband
Subject: Re: Topband: A Bit Off Topic

 

EHam is back up; here it is:

www.eham.net/ehamforum/smf/index.php/topic,102393.msg834797.html#msg834797

It's a long post, but no one complained since there's so much good info in it. John is a smart fellow.

73, Mike

www.w0btu.com

 

On Sat, Jun 27, 2015 at 5:14 PM, Mike Waters <mikewate at gmail.com> wrote:

Hi Charlie,

 

On Sat, Jun 27, 2015 at 4:06 PM, Charles Cu nningham <charlie-cunningham at nc.rr.com> wrote:

 Well, a few things to keep in mind, Mike:

 ·        Each time an MOV breaks down, Its breakdown voltage decreases a little, taking its break down voltage closer to the peak voltage of the line cycles.

 

Understood. 

That Sycom meter base surge suppressor has been replaced three times at my request. The last time, I made sure that it was a brand-new unit for the very reason that you state. Still, it didn't work like I thought it should.

 

Regarding ground rods – if the ground rods take lightning strikes, the soil around the ground rod can “glassify” become glass from the heat of the lightning surges. As the soil  glassifies, the rod is then surrounded by an INSULATOR –  making it rather ineffective. It can be a pain, but it’s worth checking ground rods from time-to-time for degradation.

 

WOW! That's something that never occurred to me.
 

Here's a class-act company that specializes in very low resistance grounding systems for as-good-as-it-gets lightning protection.
http://www.lyncole.com
A local friend of mine (W0PM, Rayfield Communications) has successfully Lyncole's products on several tall commercial towers. They use a special ground rod along with a thick layer of a powdered(?) chemical mix that surround it. John is quite knowledgeable about this. If eHam were up, I'd send you a link to something he said there.



 In keeping with Tom’s remarks, the meter-base suppressors ARE common-mode suppressors that sit directly across the 240 volt line phases with a direct common-mode ground return.


 

I cannot think of a way of (or reason for) wiring a 240 volt 3- wire surge suppressor so that there is only common mode protection but no differential mode protection. How could that be the case? If there are two 130 VAC MOVs from each leg to ground, wouldn't both of them conduct if a HV spike was present across both legs?

 

73, Mike