On Jul 13, 3:48 pm, derek wrote:
Met an old ham a couple of weeks ago he had recently moved into a
senior citizens complex and was unable to have antennas of any sort
erected, all he had was, as he put it, a piece of wire in the loft.
After a bit of thought I decided to make one of Art's antennas for
him. I made a former 16" long by 10.5"diameter and contra-wound
aprox 550' of twisted (1100' single) 19 gauge copper magnet wire onto
it, covered same in pvc tape and took it over to him yesterday
morning, he took some swr readings they were as follows.

SWR
1.8 = 1.2 :1
3.75 = 1 :1
7.075 = 1.7 :1
14.075 = 4 :1
21.075 = 6 :1

He did not have a variometer but is going to build one, will post
results when He gives them to me, I left him playing with the antenna
and he seemed to be a very happy man.

Derek

Good on you Derek. It would appear the instructions on my page
worked out OK for you.
Can you give details about the former you made and what was the length
of the turnings?
If you like I can send details on how to make the variometer and it
wouldn't surprise me if tha
local club doesn't ask you for a demonstration how to make one.
You have no idea how happy you made that ham since he can now work
anywhere
he wants to as well as the local repeaters I garantee he was not a
happy man in the old peoples home
and having the ability of just a piece of wire
Cheers
Art
Unwinantennas.com/

On Jul 14, 8:16 am, Art Unwin wrote:


Hi Art

I made the former out of plywood and half inch doweling, when
twisting the wire I aimed for two full turns per inch, the wire I
used filled the former with about 6 to 8 foot of wire over. As a
matter of interest you say on your page you used aprox 2000 feet of
wire on a 12 by 12 inch former, from my experience with my former I
would say you only used aprox 1000 feet of wire.

Derek

On Jul 14, 8:16 am, Art Unwin wrote

Hi Art
The details for the variometer would be of help if you could
oblige thank you.

Derek

Hi Art
The details for the variometer would be of help if you could
oblige thank you.

Derek

The following explains the construction:

http://www.g0mrf.freeserve.co.uk/variometer.htm

Variometers can be very lossy variable inductors. For proper
matching 2 elements are required.

73,

Frank

On Jul 14, 10:51 am, "Frank" wrote:
Hi Art
The details for the variometer would be of help if you could
oblige thank you.

Derek

The following explains the construction:

http://www.g0mrf.freeserve.co.uk/variometer.htm

Variometers can be very lossy variable inductors. For proper
matching 2 elements are required.

73,

Frank

up that is similar to mine except I split the coilnumbers by two and
it is still to insensitive so now I have to put a blob of solder in
betwwee the coils to short them until I get the right ratio to suit
the antenna. I like to slow down the swr meter so that I constantly do
not scoot pass the right point

"Art Unwin" wrote in message
...
On Jul 14, 10:51 am, "Frank" wrote:
Hi Art
The details for the variometer would be of help if you could
oblige thank you.

Derek

The following explains the construction:

http://www.g0mrf.freeserve.co.uk/variometer.htm

Variometers can be very lossy variable inductors. For proper
matching 2 elements are required.

Oh, that little, that's thing is for girls, see
http://w5jgv.com/variometer/variometer.htm
Mike :-)

On Jul 14, 2:29 pm, "amdx" wrote:
"Art Unwin" wrote in message

...

On Jul 14, 10:51 am, "Frank" wrote:
Hi Art
The details for the variometer would be of help if you could
oblige thank you.

Derek

The following explains the construction:

http://www.g0mrf.freeserve.co.uk/variometer.htm

Variometers can be very lossy variable inductors. For proper
matching 2 elements are required.

Oh, that little, that's thing is for girls, seehttp://w5jgv.com/variometer/variometer.htm
Mike :-)

That one is at least four times the coil turns needed. The previous
one was at least two times the number of coils need.
And if the wire length used was 1100 feet or so the latter also is
much more than required and can be divided by two again.
The idea is not to put a 1000 feet of wire on the variometer or to use
the radiator beyond the HF bands!

Frank wrote:

The following explains the construction:

http://www.g0mrf.freeserve.co.uk/variometer.htm

Variometers can be very lossy variable inductors. For proper
matching 2 elements are required.

A general rule of thumb for electrically small antennas is:
small-broadband-efficient, pick any two. One of the common features of
many small antennas is some lossy component or components which make the
bandwidth acceptable. Of course, this also means lowered efficiency,
often to an extreme extent. But most amateurs are able to measure SWR
and almost none are able to measure efficiency, so the loss fools a lot
of people into thinking the small antenna is performing well. I suspect
the variometer is the "secret ingredient" in this case, and that its
chief function is to provide loss. People duplicating the antenna might
try substituting a non-inductive resistor as a simpler way to achieve
the same result.

This isn't to say that a small inefficient antenna "doesn't work". I've
personally worked over 30 countries with a watt and a half on 40 meters
using simple antennas, and many, many people have done a great deal
better with much lower power. So you can still work a lot of stations
with a 100 watt rig and 1% efficient antenna.

Roy Lewallen, W7EL

On Jul 14, 10:51 am, "Frank" wrote:
Hi Art
The details for the variometer would be of help if you could
oblige thank you.

Derek

The following explains the construction:

http://www.g0mrf.freeserve.co.uk/variometer.htm

Variometers can be very lossy variable inductors. For proper
matching 2 elements are required.

73,

Frank

2 elements required? What does that mean?

Art Unwin wrote:

...
2 elements required? What does that mean?

Who knows absolutely?

But, most likely, he means a dipole.

On a full wave monopole with no counterpoise and choking off the outer
braid ... I guess you have "one element" as opposed to "2 elements" (for
example: monopole-with-counterpoise/dipole 1/4 wave, 1/2 wave.)

But then, I am guessing. scratches head

Regards,
JS