"Barrett" wrote in
k:

I have up a half size G5RV and want to add 80 metres it. I don't have
the space for a full size.

What is best to go for a 80m inductor kit or a pair of 80m traps?

Thanks



Reading through the responses, it seems that your requirement is actually
for a shortened wire antenna for 80 and 40.

The starting materials are a half sized G5RV (which is not a G5RV, but
one of the many variants).

You could salvage materials from the G5RV to make a trapped 80/40 dipole.

(The traps do not simply work as an on/off switch to disconnect the end
sections as implied by some. They might be seen to work that way if they
were resonant at the operating frequency, but they need not be, and there
is good reason for them to not be resonant at any operating frequency.)

Google around for designs for an 80/40 trapped dipole, there are plenty.
Decent articles will include details of the physical construction of the
traps.

There is a design on my web site, but it is probably too long for you (we
don't know your length requirements other than less than a G5RV, you
chose to not share that). Nevertheless, it might be an interesting read,
see http://www.vk1od.net/coaxtrap/8040.htm .

These type of antennas are affected by their environment, so you should
expect to need to fine tune the configuration. Be wary of varying
specific trap designs, you might dig a hole for yourself.

Owen

Sorry about that, I should of said the length of my garden.
From the bottom of the garden up to the wall of the house it is 60 feet and
I do not have any chimney stacks to run wires from. My neighbours are happy
with a 20 foot pole at the bottom of the garden. Any higher and there not
happy about it so that's it for the height. At least there ok with a 20'
pole. I am limited on length of wire and unfortunately the height as well.
So any help is welcome.


"Owen Duffy" wrote in message
...
"Barrett" wrote in
k:

I have up a half size G5RV and want to add 80 metres it. I don't have
the space for a full size.

What is best to go for a 80m inductor kit or a pair of 80m traps?

Thanks



Reading through the responses, it seems that your requirement is actually
for a shortened wire antenna for 80 and 40.

The starting materials are a half sized G5RV (which is not a G5RV, but
one of the many variants).

You could salvage materials from the G5RV to make a trapped 80/40 dipole.

(The traps do not simply work as an on/off switch to disconnect the end
sections as implied by some. They might be seen to work that way if they
were resonant at the operating frequency, but they need not be, and there
is good reason for them to not be resonant at any operating frequency.)

Google around for designs for an 80/40 trapped dipole, there are plenty.
Decent articles will include details of the physical construction of the
traps.

There is a design on my web site, but it is probably too long for you (we
don't know your length requirements other than less than a G5RV, you
chose to not share that). Nevertheless, it might be an interesting read,
see http://www.vk1od.net/coaxtrap/8040.htm .

These type of antennas are affected by their environment, so you should
expect to need to fine tune the configuration. Be wary of varying
specific trap designs, you might dig a hole for yourself.

Owen

When I put the homebrew HF traps in my wire Ariel how do I calculate the
length of wire before and after each trap for each band?

Thanks


"Barrett" wrote in message
.. .
Sorry about that, I should of said the length of my garden.
From the bottom of the garden up to the wall of the house it is 60 feet
and I do not have any chimney stacks to run wires from. My neighbours are
happy with a 20 foot pole at the bottom of the garden. Any higher and
there not happy about it so that's it for the height. At least there ok
with a 20' pole. I am limited on length of wire and unfortunately the
height as well. So any help is welcome.


"Owen Duffy" wrote in message
...
"Barrett" wrote in
k:

I have up a half size G5RV and want to add 80 metres it. I don't have
the space for a full size.

What is best to go for a 80m inductor kit or a pair of 80m traps?

Thanks



Reading through the responses, it seems that your requirement is actually
for a shortened wire antenna for 80 and 40.

The starting materials are a half sized G5RV (which is not a G5RV, but
one of the many variants).

You could salvage materials from the G5RV to make a trapped 80/40 dipole.

(The traps do not simply work as an on/off switch to disconnect the end
sections as implied by some. They might be seen to work that way if they
were resonant at the operating frequency, but they need not be, and there
is good reason for them to not be resonant at any operating frequency.)

Google around for designs for an 80/40 trapped dipole, there are plenty.
Decent articles will include details of the physical construction of the
traps.

There is a design on my web site, but it is probably too long for you (we
don't know your length requirements other than less than a G5RV, you
chose to not share that). Nevertheless, it might be an interesting read,
see http://www.vk1od.net/coaxtrap/8040.htm .

These type of antennas are affected by their environment, so you should
expect to need to fine tune the configuration. Be wary of varying
specific trap designs, you might dig a hole for yourself.

Owen

On Wed, 16 Apr 2008 14:39:27 +0100, "Barrett"
wrote:

When I put the homebrew HF traps in my wire Ariel how do I calculate the
length of wire before and after each trap for each band?

Hi Barrett,

1. You either copy an existing design and follow their specifications
for this explicitly;

2. You model the design and plan to trim length, and/or adjust turns;

3. You throw something together and (again) plan to trim length,
and/or adjust turns.

The placement of the coil along the radiator by actual distance and
proportion, seriously changes its requirements for any application.
That is to say, a 50 turn coil, with turns every 3mm, and a 4cm
diameter will work for one frequency at one position for one length of
wire ONLY. And even height above ground may upset this too; but
perhaps not as much as the first set of variables.

73's
Richard Clark, KB7QHC