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Author Topic: Grounding  (Read 631 times)
W9FFC
Member

Posts: 32




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« on: November 29, 2009, 07:44:36 PM »

My shack is on the second floor making it impossible to run a short ground wire.
Forget the MFJ artificial ground.
If I were to run approximately 50' of 2 or 3 size wire, could I expect a reasonable ground?
73............Bob
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AA4PB
Member

Posts: 12644




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« Reply #1 on: November 30, 2009, 06:26:44 AM »

No.

What are you trying to achieve with the ground? With a proper antenna installation you don't need any type of RF ground at the radio. The electrical safety ground should be provided by your home's electrical system (3-wire plug). The lightning safety ground on the coax shields should be outside, just before the coax enters the building. This ground must be tied back to the electrical system ground with #6 wire for safety reasons.
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W9FFC
Member

Posts: 32




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« Reply #2 on: November 30, 2009, 07:39:03 AM »

Thank you, I guess my age is showing. Years ago it was imperative to have a good rf ground. Until recently I was always able to achieve this.
Anyway, thanks again!

73......Bob..........W9FFC
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AA4PB
Member

Posts: 12644




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« Reply #3 on: November 30, 2009, 08:08:44 AM »

Bob, the need for an RF ground always was and still is dependent on the antenna. If you use an end-fed wire, for example, you will need an RF ground at the tuner. If you use a balanced antenna like a dipole then you shouldn't need any RF ground at all. If you use something like a 1/4 wave vertical then the radials (outside) provide the RF ground and you shouldn't need one at the radio.

At any rate, unless the grounding wire is very short it will not provide an RF ground at all for some frequencies (any frequency where it is an odd multiple of 1/4 wavelength). If the far end is connected to a perfect ground, a quarter wave back the impedance will be high (i.e. no RF ground at all). It doesn't matter if you use #28 wire or #000 wire as far as this resonance is concerned.

If you do use an antenna that needs an RF ground then it is best to design it so that the feed point and the RF ground are outside. For a multi-band inverted-L place the tuner outside close to the ground and use a short wire to connect the tuner ground to multiple buried radials.

73,
Bob
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WB0MCO
Member

Posts: 81




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« Reply #4 on: December 03, 2009, 09:53:08 PM »

"With a proper antenna installation you don't need any type of RF ground at the radio" ?? This could be
debated all day long.Ground radials,counterpoise should be part of the antenna and the Rf Ground at the radio.
I run 2" copper strap from rear of every piece of
radio equipment to a buss bar, then from the bar with
the same size strap outside to my common point ground
system.
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