Although I don't know if my system, or anyone's system could really take the
full brunt of a direct strike (although I know several have claimed so), I
do agree that even a few tenth's of an ohm of resistance is a serious issue.
Also, in the event of taking, let us say, a heavy load from at least a very
nearby strike, you might have enough current to heat joints up enough to
melt solder and even silver solder. For that reason, I braze all my ground
connections with pure copper brazing rod (ok, it has a few percent
phosphorous mixed in) that melts at a temperature only a little less than
that of the copper conductors themselves. In this way I get a very low
impedance connection that won't blow apart under a very heavy load.
If, for whatever reason, I can't braze it, then I use very heavy mechanical
bonding, perhaps in combination with solder or silver solder, to try to
insure the connection survives under very heavy loads.
Better than this I cannot do. Incidentally, I use large diameter, soft
copper, refrigeration copper tubing for my ground conductors where possible.
This can be selected in a size to fit firmly over the OD of the ground rods,
and then brazed in place. Very low impedance, as long as the length is
either significantly less than 1/4 wave or else a half wave long at the
frequency of interest. Otherwise you get a very high RF impedance, and no
ground.
73 de Gary, AA2IZ
----- Original Message -----
From: "Mike Hyder -N4NT-" <n4nt_m_o_hyder@charter.net>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Tuesday, November 29, 2005 10:44 AM
Subject: Re: [TenTec] Station and AC Ground
> Problem with this (as I understand the convoluted explanation) is where
> instead of Zero ohms, you have 0.1 or 0.2 ohms. Then take a lightning
> strike with a current of maybe 10,000 amps and you will see that there can
> be quite a voltage drop.
>
> Mike N4NT
>
> ----- Original Message -----
> From: "JAMES BRASSELL" <jimbrass@bellsouth.net>
> To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
> Sent: Tuesday, November 29, 2005 9:37 AM
> Subject: [TenTec] Station and AC Ground
>
>
> Hey, All.
>
> Just a quick observation and question. I have read many posts on this
site
> about having the station and AC mains grounds tied together. For my
> observation, when you have a separate station ground (and I do; a good
one)
> and all pieces of equipment are tied to that ground and the ground wire
from
> the AC plug is tied to the equipment chassis then you have effectively
tied
> the AC mains ground to the station ground. I have measured from the AC
> mains ground to the station ground and it is zero ohms, with no voltage
(to
> the microvolt between them). I have looked in the equipment and the AC
> ground is tied directly to the chassis, not through a board. My question
> is, if the equipment is grounded and you have a good AC mains ground is
that
> not tying the mains and station grounds together? I could see where one
> might have a problem if the ground in the equipment was achieved through a
> circuit board and the equipment was not otherwise grounded. I feed two
> verticals, GAP Titan and
> Voyager, and run 1500 watts into them on a regular basis without any RF
> problems. What say you?
>
> Jim, K4ZMV
> _______________________________________________
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> TenTec@contesting.com
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>
>
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