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Author Topic: lightning-arrestor for transmission-line  (Read 2199 times)
KB3RHV
Member

Posts: 41




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« Reply #15 on: April 10, 2009, 04:45:03 PM »

"I also question whether two ground rods is a sufficient RF ground for an end-fed antenna like an inverted-L. You may get by with it if the L is 1/2 wavelength long but not on bands where the L is some other length."

Yea that's what I thought as well, until I started reading up on the SGC tuners and the ICOM's. If you follow Icom's recommended wire length formula, it will work.

The total length of wire run was 85Ft and it worked out well.

SGC Notes:
http://www.sgcworld.com/Publications/Books/hfguidebook.pdf

http://www.sgcworld.com/Publications/Books/stealthbook.pdf

http://forums.qrz.com/showthread.php?p=1390742
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KM3K
Member

Posts: 299




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« Reply #16 on: April 10, 2009, 07:10:54 PM »

To K9KJM...
"ALL of my own arrestors and coax switches are INDOORS."
After reading that, I was very interested to go in that direction myself; it'd save lots of problems for me.
I thought, "Maybe K9KJM has some pictures on the web of his shack and I could get some good ideas".
You know the story..one picture worth a thousand words.
So Googling on your call, I was impressed to get over 4200 hits and this one "http://www.n5wj.com/gallery/shack/HP_Feb_2005_080" has what I think could be your panel in the immediate background. If it is, I wish I could see more.
73
Jerry, KM3K
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K9KJM
Member

Posts: 2415




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« Reply #17 on: April 11, 2009, 12:42:00 AM »

KM3K, Yes, That is indeed a photo of one of my single point ground panels. (That panel is bonded to the outdoor ground system with 6 inch wide flat copper strap and #2 copper wire)

Email me your email address and I can send you more photos if you want.  
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KB9CRY
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Posts: 4283


WWW

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« Reply #18 on: April 11, 2009, 04:04:20 AM »

Concerning ground-radials, is bare-wire preferred and what gauge would you suggest?


Either or.  I use 18 gauge, stranded, insulated.  It is heavy enough that it lays nicely on the contours of the ground.  I just mow the grass short and make home made staples from electric fence wire to hold it down.  Within a month, the grass has absorbed it and you can't see it.
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AA4PB
Member

Posts: 12840




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« Reply #19 on: April 11, 2009, 09:17:47 AM »

Yea that's what I thought as well, until I started reading up on the SGC tuners and the ICOM's
------------------------------------------------------
Actually, I haven't read anywhere that SGC recommends two ground rods over radials. They show numerous "compromise" installations when you are portable or mobile, but for a fixed station they recommend plenty of radials. I don't doubt that your friend's two ground rods "work", but I suggest that he could improve the efficiency with some radials.

These unbalanced tuners are not magic. They require that return currents flow in a counterpoise somewhere. Even SGC can't get around the rules of physics :-) The more efficient you make that counterpoise, the more of you signal will be radiated instead of being disipated in ground losses.
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