Sorry, somehow I just couldn't resist.
73,
Marsh, KA5M
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of Brian
Carling
Sent: Monday, January 19, 2015 4:28 PM
To: Marsh Stewart
Cc: <towertalk@contesting.com>
Subject: Re: [TowerTalk] w7ekb & ground rods
Aaargh! Siri strikes again!
Best regards - Brian Carling
AF4K Crystals Co.
117 Sterling Pine St.
Sanford, FL 32773
Tel: +USA 321-262-5471
> On Jan 19, 2015, at 4:58 PM, Marsh Stewart <marsh@ka5m.net> wrote:
>
> I've just got to ask - who were the "experts" who said adding two (2) more
> "radios" (sic) would help?
>
>
> -----Original Message-----
> From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of
Brian
> Carling
> Sent: Monday, January 19, 2015 3:54 PM
> To: Jim Lux
> Cc: towertalk@contesting.com
> Subject: Re: [TowerTalk] w7ekb & ground rods
>
> 910 micro Henry sounds like a very useful loading coil to me!! I have had
no
> difficulty using a ground rod as a counterpoise to my vertical. In fact
it's
> done extremely well. I added two radios because the experts said it would
> make it work better. It didn't.
>
> Best regards - Brian Carling
> AF4K Crystals Co.
> 117 Sterling Pine St.
> Sanford, FL 32773
>
> Tel: +USA 321-262-5471
>
>
>
>
>>> On Jan 19, 2015, at 12:15 PM, Jim Lux <jimlux@earthlink.net> wrote:
>>>
>>> On 1/19/15 8:45 AM, Ken wrote:
>>> It seems to me that the ground above my rock layer (@ 36-40") gets
> really dry during the summer. Does that dry dirt have enough conductivity
> to be useful? I do not know the answer to that question.
>>>
>>> Are there different answers depending on why we have the ground rod?
(RF
> ground, power line ground, or lightning protection)
>>
>> Yes..
>>
>> ground rods make terrible RF grounds, in general (where RF is HF and up):
> skin effect means that wires and rods have high ac resistance. (skin depth
> in copper at 10 MHz is about 0.8 mils/0.02 mm.)
>>
>> They also have significant series L (1 microhenry/meter for a wire.. so a
> 30 foot run to the rod is a 10 uH inductor, that's 600 ohms reactive
> impedance.
>>
>> Rods are really for electrical safety ground and/or lightning ground. And
> they don't work all that well for that, unless deployed in large numbers.
> The advantage of a rod is that it's easy to install by driving, but as an
> electrical connection to the earth, it's just not that wonderful: the
> surface area is quite small (8 foot rod, 1" in diameter is only 300 square
> inches. You could probably do better, electrically, by burying a 1 foot
> square plate (288 square inches).
>>
>>
>> Rods are also used in phone and power line applications.. you drive a rod
> at every pole (or wrap the ground wire around the foot of the pole when
> planting it). Even if any one rod has crummy characteristics, there's
lots
> of other rods in the circuit to help establish the common voltage
reference
> and provide a fault current return. I've had telco installers drive a new
> rod next to the existing rods on the general principle that at least they
> knew the new rod was in good condition: faster to just do a new rod than
to
> test the existing one.
>>
>>
>>
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>>
>>
>>
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