On Sun, 29 Feb 2004 12:58:41 -0000, "Richard"
wrote:


"Tam/WB2TT" wrote in message
...
Richard,

Why don't you go to the web site you referenced, and click on "Ask seller
a
question", or doesn't he know? I did not read the whole thing. With the
loading coils, it might be an 11 meter antenna.

The seller does not know.

Funny, but figuring out what frequency an antenna might be for, even with
the physical and electrical parameters spelled out must be more difficult
than I imagined. I'm really surprised that after giving these details lower
down in the thread, the antenna cannot be figured. I'm gobsmacked.

You are right in the case of a simple antenna.

Loading coils and similar make a determination without actually
examining it far more difficult. You may not have provided every bit
of data required for people to VOLUNTARILY provide you with an answer.

An antenna design book might help, as would some careful testing.

You don't need to determine exactly what it is, you just need a "go/no
go" test for your frequencies of interest. Low power Xmit and an SWR
meter would help.

Happy trails,
Gary (net.yogi.bear)
------------------------------------------------
at the 51st percentile of ursine intelligence

Gary D. Schwartz, Needham, MA, USA
Please reply to: garyDOTschwartzATpoboxDOTcom

Have you tried to put the model number (I couldn't read it in the
picture) into Google to see what it returns?

"Stevens" wrote in message
...
Have you tried to put the model number (I couldn't read it in the
picture) into Google to see what it returns?

Yea, done that and nuthin'.

I wonder what the quarter wave frequency would be for a length of wire 30"
long with a base coil of approximately 0.330uH. Same wonder with a 0.660 uH
coil.

I wonder what the quarter wave frequency would be for a length of wire 30"
long with a base coil of approximately 0.330uH. Same wonder with a 0.660
uH
coil.
====================================

Rich, wonder no longer.

Download program BOTLOAD2.

For a 30" rod -

With base loading coil 0.33 uH, Fres = 69.1 MHz.

With a base loading coil 0.66 uH, Fres = 55.7 MHz.

----
Reg, G4FGQ
.................................................. ..........
Regards from Reg, G4FGQ
For Free Radio Design Software go to
http://www.btinternet.com/~g4fgq.regp
.................................................. ..........

"Reg Edwards" wrote in message
...
I wonder what the quarter wave frequency would be for a length of wire
30"
long with a base coil of approximately 0.330uH. Same wonder with a
0.660
uH
coil.
====================================

Rich, wonder no longer.

Download program BOTLOAD2.

For a 30" rod -

With base loading coil 0.33 uH, Fres = 69.1 MHz.

With a base loading coil 0.66 uH, Fres = 55.7 MHz.

The antenna has three radials, and each has a loading coil right at the
begining.

Now I would have thought that at the feedpoint, the impedance would be low,
so I think then one would assume the radials are suppossed to acting as 1/4
wavelength radials. If that were true, then the freqency at which the
radials are quarter wavelength would be the operating frequency of the
antenna.

I've remeasured the coils after removing the rubber insulation to get a
better look.

For Radial #1

Length: 6mm
O.D.: 11mm
Turns: 9
Pitch: closewound


For Radial #2

Length: 6mm
O.D.: 11mm
Turns: 9
Pitch: closewound


For Radial #3

Lenngth: 13mm
O.D.: 11mm
Turns: 20
Pitch: closewound

I wonder if the coils should all be different, but by mistake the radials 1
& 2 are identical. I just don't know.

The new length of the radial is 72mm orabout 28.5". They are 2mm diameter
stainless steel rods.

I tried to use Botload2, but not sure what I'm doing. Can you please do the
two calculations again Reg? Ta.

I see, you wish to know the two resonant frequencies of the radials.

Measure the dimensions of the radial loading coils and calculate their
inductance. Make no attempt to measure inductance.

First you will have to enter a crude frequency into program BOTLOAD2.

Then insert the overall length of a radial into the program. You MUST
include the length of the loading coil in the length.

Also insert the diameter of the radial in the program.

Use keys 1 and 2 to VARY frequency up and down until the program indicates
the value of loading coil is equal to its actual value. ie., the value you
have calculated from its dimensions.

The frequency at which the indicated coil inductance is equal to the value
you have calculated is the resonant frequency of the radial.

You don't really need the coil-design part of the program. Initially just
enter some crudely correct values for the dimensions. But you can use it to
check your calculation of coil inductance.

You will be using the program in a somewhat different manner to its primary
purpose. You are using it to measure frequency whereas frequency is really
a program input parameter.

The only output parameter you are interested in is coil inductance.

Let me know how you get on.
----
Reg, G4FGQ

==================================

"Richard" wrote in message
...

"Reg Edwards" wrote in message
...
I wonder what the quarter wave frequency would be for a length of wire
30"
long with a base coil of approximately 0.330uH. Same wonder with a
0.660
uH
coil.
====================================

Rich, wonder no longer.

Download program BOTLOAD2.

For a 30" rod -

With base loading coil 0.33 uH, Fres = 69.1 MHz.

With a base loading coil 0.66 uH, Fres = 55.7 MHz.

The antenna has three radials, and each has a loading coil right at the
begining.

Now I would have thought that at the feedpoint, the impedance would be
low,
so I think then one would assume the radials are suppossed to acting as
1/4
wavelength radials. If that were true, then the freqency at which the
radials are quarter wavelength would be the operating frequency of the
antenna.

I've remeasured the coils after removing the rubber insulation to get a
better look.

For Radial #1

Length: 6mm
O.D.: 11mm
Turns: 9
Pitch: closewound


For Radial #2

Length: 6mm
O.D.: 11mm
Turns: 9
Pitch: closewound


For Radial #3

Lenngth: 13mm
O.D.: 11mm
Turns: 20
Pitch: closewound

I wonder if the coils should all be different, but by mistake the radials
1
& 2 are identical. I just don't know.

The new length of the radial is 72mm orabout 28.5". They are 2mm diameter
stainless steel rods.

I tried to use Botload2, but not sure what I'm doing. Can you please do
the
two calculations again Reg? Ta.