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Re: [TenTec] RFI question for Orion and other TT rigs

To: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Subject: Re: [TenTec] RFI question for Orion and other TT rigs
From: Robert & Linda McGraw K4TAX <RMcGraw@Blomand.Net>
Reply-to: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Sun, 26 Jun 2005 13:34:15 -0500
List-post: <mailto:tentec@contesting.com>
One other very important point is to make sure that your station is not 1/4 
wave, electrically, above ground.  Many times in today's world the antennas 
that we use are not required to have any type of ground to properly operate 
or radiate efficiently.  These are generally center fed dipoles either with 
coax or balanced feeds or  beams.  On the other hand, off center fed 
antennas (Windom) end fed wires, slopers, verticals and such do require a 
good ground system.  And a driven ground rod or two does not make a good 
ground system.  It is more extensive than that.

As to 1/4 wavelength grounds, an example of this point is a driven ground 
connected to the station by some 16 ft of wire.  This will likely place the 
station at a maximum voltage point on 20M.  Typically not a good situation 
where the load not being resistive and not near 50 ohms.  RF will flow on 
the shield and back to the station.  In this case, no ground is better than 
this ground.  Actually, correcting the load Z is the better approach.

I find in general that hams need to have a better understanding of RF 
ground, DC ground, and lightning protection ground.

Bob, K4TAX

----- Original Message ----- 
From: "Tommy Alderman" <aldermant@alltel.net>
To: "'Discussion of Ten-Tec Equipment'" <tentec@contesting.com>
Sent: Sunday, June 26, 2005 1:20 PM
Subject: Re: [TenTec] RFI question for Orion and other TT rigs

>I believe what you just said was this:
> "Roy,
> One of the best and easiest ways to avoid "RF in your shack" is to make
> sure that one half the length of your antenna plus the total length of
> your feed line is NOT an odd quarter wavelength long. The reason for
> that is if that total is an odd quarter wavelength, you will have a
> maximum voltage field in your shack. The second most easiest thing to
> avoid is do not let the end of any of your antennas terminate directly
> over your shack, as that too, is a high voltage field point.
> Tommy - W4BQF"

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