Sounds good, Vinnie....................feel free to e-mail me directly if
you have any questions.

Pete

"Vinnie S." wrote in message
...
On Sun, 10 Apr 2005 19:58:28 GMT, "Pete KE9OA"

wrote:

Hey Vinnie............I can help you. The formula for a 1/4 wavelength
radiator is (234 / F) whereby F is the frequency in MHz. This will give
you
the length in feet. For the radials, (237 / F) will give you that length.
Always remember...multiply the radiator length by 1.05 and that is another
way of calculating the 1/4 wavelength radials.
The feedpoint impedance of a 1/4 wave ground plane is 37 ohms when you
have
the radials at a 90 degree angle with respect to the radiator. If you have
the radials drooped at a 45 degree angle, the impedance rises to
approximately 50 ohms.

So far, that is what I have read. What I am going to do is this. I am
going to
add the 45 angled GP, simply because it is fairly cheap, and because it
will be
much easier to put it up now, than later. The formula you gave indicates
that
radials should be about 8.8 feet at 27 MHz. If these radials fair poorly,
I will
take Lancer's advice and build my own. For some reason, the radials are 6
feet.
I don't know if they ran 9 feet of wire in there, or what.


If you have a single radial drooped at a 180 degree angle with respect to
the radiator, the impedance rises to 75 ohms.

I won't do this.

There was an article in RF Design magazine a few years back, explaining
why
certain impedances are used in the RF industry.
72 ohms was the impedance that produced minimum cable losses...........50
ohms is a happy medium.
On a final note...........at 37 ohms, you will have a VSWR of 1.3 to
1.................at 75 ohms, you will have a VSWR of
1.5 to 1. What is the difference here? For a transmitter with a tube
output
and an internal matching network, you wouldn't really see much effect. For
a
typical solid state transmitter, there would be some difference between
the
two antenna impedances, because the broadband solid state transmitter
would
be called upon to deliver more current to the antenna. It probably
wouldn't
have any effect, unless the ALC circuit was aggressive in its operation.
In
this case, power foldback would occur into the 37 ohm load. Would it
happen?
Probably not.
I hope this helps.

Pete


It's does help, Thanks ! I am borrowing an Autek RF analyzer to check the
antenna while I am up in the tree. Most people that have purchase this
antenna,
say that it is tuned very well to 27.205. I should be flat up and down in
CB and
10 meters for about 1 MHZ.

I will follow up.

Vinnie S.