I did mention, it's a 5BTV that breaks all the rules. I love it. It outperforms
most other antennas I've ever used. Must be the wonderfully wet Florida soil or
something!
Best regards - Brian Carling
AF4K Crystals Co.
117 Sterling Pine St.
Sanford, FL 32773
Tel: +USA 321-262-5471
> On Jan 19, 2015, at 5:28 PM, <ve4xt@mymts.net> <ve4xt@mymts.net> wrote:
>
> There are any number of reasons why an antenna system might trick you into
> thinking it's defying 100 years of antenna engineering.
> Common-mode currents, unintended interactions, etc. Plus, you didn't mention
> what vertical it was: if it's a vertical dipole or a end-fed half-wave design
> (F12, Cushcraft R-series of verticals, etc.), it's very likely you'd see
> little benefit from the addition of two — I assume you meant — radials.
> If it's a traditional 1/4-wave monopole (5BTV, DX-88, HF-9V, etc.), then
> likely what's happening is stuff in your home and yard is behaving like
> radials behind your back.
> Which is not to say you can't or shouldn't accept a very well-working system
> when you happen upon one. Lots of people have great success with
> half-slopers, even though it's not the greatest of antenna designs.
> Finally, it's very likely that even with no interactions or common-mode
> currents, two radials will have very little impact.
> 73, kellyve4xt
>> From: bcarling@cfl.rr.com
>> Date: Mon, 19 Jan 2015 16:54:04 -0500
>> To: jimlux@earthlink.net
>> 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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>>> TowerTalk@contesting.com
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