[TowerTalk] Radial Connection to tower

[Stan Stockton]

Thanks for the responses! Sounds relatively easy to fix. I was worried I was going to not learn anything today :-).

73...Stan, K5GO

Sent from Stan's IPhone



> On Dec 13, 2015, at 12:56 PM, Richard (Rick) Karlquist <richard at karlquist.com> wrote:
> 
> You can estimate 20 nH per inch for these hook up
> wires. On 80 meters, think of that as as about
> a half ohm of inductive reactance per inch,
> or 6 ohms of inductive reactance per foot.
> Thinking of it that way, you can see why a single
> 10 inch wire in series with your ground connection
> isn't a great idea. You might try modeling it
> and see if it rises to the "noticable" level.
> 
> I have a 230 foot diameter ground screen with
> wires spaced 3 feet apart in each direction.
> When I first completed this, I placed a 40
> meter vertical at the center junction, such
> that there were four wires emanating from the
> shield of the coax connector. These 4 wires
> run 3 feet until they reached the next junction,
> etc. The driving impedance of this was
> 70 ohms, despite being over a gigantic ground
> screen. After adding 30 foot radials to tie it into
> the ground screen 30 feet away from the vertical,
> the impedance steadily decreased with the
> number of radials until it reached the
> theoretical value of 36 ohms. This is the
> kind of weird stuff that happens if you deviate
> from the classical radial paradigm.
> 
> Rick N6RK
> 
> 
>> On 12/13/2015 2:28 AM, Stan Stockton wrote:
>> Rick,
>> 
>> I noticed this response and have a question.
>> 
>> Background:
>> 
>> I have an 80m 4 Square insulated 25G verticals and another tower that is grounded that I shunt feed for 160m.  In all cases the radials are soldered to a wire that goes around the concrete bases of the towers.  Then there is a wire or two from the ring to a plate that that has a female UHF connector on each of the 4 Square towers or to a tower leg on the one that is shunt fed.  Those wires are probably 12-18 inches long and maybe #10 or so.
>> 
>> Question:
>> 
>> Based on your measurements, do you think I can make a noticeable improvement by doing something different?
>> 
>> Thanks... Stan, K5GO
>> 
>>> On Dec 12, 2015, at 10:26 AM, Richard (Rick) Karlquist <richard at karlquist.com> wrote:
>>> 
>>> I have played around with this problem and made some actual
>>> measurements.  My conclusion was you need a considerable number
>>> of radials between the ring and the tower; at least 12 and
>>> preferrably 20 or 30, especially on 40 meters.  A mesh is a
>>> lot of trouble and would need to be fairly closely spaced
>>> to be effective.
>> 
>>