ART'S ANTENNA
 

Roy Lewallen wrote:
With only one adjustable element, you can get a
specific R, say, or X, but not both.

With only one adjustable element, i.e. ladder-line length,
I get X=0 and 35 R 85 ohms which is close enough to
50 ohms for most of us non-perfectionists.

http://www.w5dxp.com/notuner.htm
--
73, Cecil http://www.w5dxp.com

ART'S ANTENNA
 

Then what I can do is to split the circuit in half of a varometer
and connect one in series with the positive and one in series to the
negative
so I have equal turns added or subtracted of opposite wound and
controlled by the single motor.
Sounds good

Not sure I understand what you mean. Comments by Roy, and
others, noted. All these methods are certainly valid. The first step is to
determine the actual impedance of your load before you attempt
to match it, and then design an appropriate network.
For measurement a vector network analyzer is the best method,
but expensive. The "TAPR" analyzer, by Tentec looks
good at $655. Most of the cheap analyzers are not very
accurate, and VSWR is not very useful.

The Smith Chart; provided by Dellsperger, at:
http://www.fritz.dellsperger.net/ is an excellent (free) tool for
matching network design. Also Chris Bowick's
"RF Circuit Design" (At Amazon.com) provides an
insight in the use of the Smith Chart.

Experimentation by variable: series L, shunt C, or shunt C, series L,
could provied a reasonable match. Others probably
have some practical idea.

73,

Frank

ART'S ANTENNA
 

On Jul 15, 2:44 pm, "Frank" wrote:
Then what I can do is to split the circuit in half of a varometer
and connect one in series with the positive and one in series to the
negative
so I have equal turns added or subtracted of opposite wound and
controlled by the single motor.
Sounds good

Not sure I understand what you mean. Comments by Roy, and
others, noted. All these methods are certainly valid. The first step is to
determine the actual impedance of your load before you attempt
to match it, and then design an appropriate network.
For measurement a vector network analyzer is the best method,
but expensive. The "TAPR" analyzer, by Tentec looks
good at $655. Most of the cheap analyzers are not very
accurate, and VSWR is not very useful.

The Smith Chart; provided by Dellsperger, at:http://www.fritz.dellsperger.net/is an excellent (free) tool for
matching network design. Also Chris Bowick's
"RF Circuit Design" (At Amazon.com) provides an
insight in the use of the Smith Chart.

Experimentation by variable: series L, shunt C, or shunt C, series L,
could provied a reasonable match. Others probably
have some practical idea.

73,

Frank

Yes Frank I for some reason found myself settlled on 50 0hms impedance
and I can'r remember why and I didn't make a note of it.
In retrospect I should be looking at around 200 plus or minus! This
should not change to repetitiveness of resonances which is of
importance
for all frequency coverage.
So I am going back to the 100 ohm and upwards that I started with and
first check on sw BC and then fine tune on transmit.
I also checked back on the programming and got somewhere near your
figures tho in practicality my measured impedance
were way higher. I suspect the twisting of wires is the culprit for
the differences
Regards
Art
Regards
Art

ART'S ANTENNA
 

On Jul 14, 3:10 am, derek wrote:
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

If he hasn't got a variometer he can use his tuner as a substitute.
The SWR meter he is using is referenced to 50 ohms so his readings are
false.
When using twisted wire the impedance will go very much higher than
untwisted wire
at least one hundred times . The impedance of his antenna is probably
around the 300 ohm mark so he should
add a 6 or 9 to one transformer. As a furthur adjustment he can put
the up and down wires in parallell such that the 1100 feet of wire
which is two wavelengths of the top band when wound in series is now 1
wavelength and the impedance will change accoringly. So there are
options available which the ham can chose as well as changing
connections from series to parallel as well as the diferent places he
can add his tuner in the circuit. If he stands the wire tube antenna
upright say as a lamp shade so it appears unobstrusive the radiation
will be omni radial or partialy direcftional if he tilts it and if it
is low power DX that is his hobby then the lower lobe is at least half
of that of a yagi which in his circumstances it should be ideal.Since
the wire is close wound I am not sure of the power limitations but
with it being Hi Temp magnet wire with circuitry of a wavelength I
really don't see a guy in a nursing home having a problem
One thing I am not sure of is the nearnes of the point radiation
antenna with respect to personal health so he may well want to place
it outside say as a frost protector for a rose bush or the like
Regards
Art

ART'S ANTENNA
 

On Jul 15, 7:18 pm, Art Unwin wrote:
On Jul 14, 3:10 am, derek wrote:

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

If he hasn't got a variometer he can use his tuner as a substitute.
The SWR meter he is using is referenced to 50 ohms so his readings are
false.
When using twisted wire the impedance will go very much higher than
untwisted wire
at least one hundred times . The impedance of his antenna is probably
around the 300 ohm mark so he should
add a 6 or 9 to one transformer. As a furthur adjustment he can put
the up and down wires in parallell such that the 1100 feet of wire
which is two wavelengths of the top band when wound in series is now 1
wavelength and the impedance will change accoringly. So there are
options available which the ham can chose as well as changing
connections from series to parallel as well as the diferent places he
can add his tuner in the circuit. If he stands the wire tube antenna
upright say as a lamp shade so it appears unobstrusive the radiation
will be omni radial or partialy direcftional if he tilts it and if it
is low power DX that is his hobby then the lower lobe is at least half
of that of a yagi which in his circumstances it should be ideal.Since
the wire is close wound I am not sure of the power limitations but
with it being Hi Temp magnet wire with circuitry of a wavelength I
really don't see a guy in a nursing home having a problem
One thing I am not sure of is the nearnes of the point radiation
antenna with respect to personal health so he may well want to place
it outside say as a frost protector for a rose bush or the like
Regards
Art

On the suject of transformers. In the US somebody makes a pre packaged
transformer with five female coax conections depending on the ratio
required,
Since the frequency span is so large as well various locations it may
be that his ratio will land between 6 and 9 to 1
He may want to have ratios that are not as course. What he can do is
to have two rotating contacts ie minuits and hours instead of the
single one provided
On the female conectors you place a cent or copper disk in the centre
which is your contact The rotary cam that moves the contact around is
a 5 pointed star cam with slots from each point towards the center.
The outside of the star surface moves a pin around a fifth of the way
which is the distance between coax connector. So the switch does not
just float across the contact the pin which runs on the cam goes down
and up each slot which provides a stop of rotary motionwhile the
contact is made. I would not make this until the situation proves that
you need it but it does supply matches to with one ohm or so for the
intervening distance beteen 6 and 9 to one. One last thing , If power
is to be used by others on top band it is adviseable to gang two
toroids in parallel
to avoid saturation of the toroidal material. I added the above incase
other club members decide to copy with more favourable operating
conditions
Art
unwinantennas.com/

ART'S ANTENNA
 

On Sun, 13 Jul 2008 13:48:52 -0700 (PDT), derek
wrote:

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

On Tue, 15 Jul 2008 17:18:22 -0700 (PDT), Art Unwin
wrote:

The SWR meter he is using is referenced to 50 ohms so his readings are
false.

What a curious indictment of this design. When it "works" (built to
the authur's specification too) it is a false antenna.

Of course, there are any number of oddities struggling for oxygen in
this goldfish bowl.

he can put the up and down wires in parallell
and it thus fails:
1. to be the loop Guss designed;
2. to be in equilibrium.
such that the 1100 feet of wire
which is two wavelengths of the top band when wound in series is now 1
wavelength and the impedance will change accoringly.
Equilibrium demands 1 wavelength, but the authur allows up to 100%
error. Pretty loose equilibrium there.

So what does equilibrium mean when both a loop of 1100 feet (not a
wavelength at 160M) and half that, 550 feet (not a wavelength at 160M)
are prescribed simultaneously?

When a half-wave, thin-wire dipole is called for, millions of radio
operators for 3 centuries understood that to be 95% of 262 feet
(accounting for end effect). A full wave loop was similarly closer to
525 feet than 1100 feet.

The oddities abound, but those above are enough to ignite a bonfire of
the vanities.

73's
Richard Clark, KB7QHC

ART'S ANTENNA
 

Art Unwin wrote:


On the suject of transformers. In the US somebody makes a pre packaged
transformer with five female coax conections depending on the ratio
required,

How could you consider using anything from the US! What is wrong with
you?! Everything from the US is CRAP! Especially! Anything!
Associated! With! RF!

What in the SEVEN HELLS are you thinking?!

tom
K0TAR

ART'S ANTENNA
 

Tom Ring wrote:

...
How could you consider using anything from the US! What is wrong with
you?! Everything from the US is CRAP! Especially! Anything!
Associated! With! RF!

What in the SEVEN HELLS are you thinking?!

tom
K0TAR

That argument may well be true. Can you name something made in the USA
so I could check it out?

Mostly, I am aware of things with American names, but made in other
countries. Sometimes, you I might be fortunate, enough, to find
something assembled in America--with parts made in other countries.

Like I say, the world looks like walmart, to me--nothing in walmart
(mostly!) has had an American hand in its' manufacture--only its
marketing and retail to Americans ... the actual money is going to
another nation.

Regards,
JS

ART'S ANTENNA
 

John Smith wrote:
.... Sometimes, you I might be fortunate, enough, to find ...
...

Change that to:

Sometimes, you OR I might be fortunate, enough, to find ...

Ignore the other mistakes, also ...

Regards,
JS

ART'S ANTENNA
 

On Jul 15, 7:18*pm, Art Unwin wrote:
and if it
is low power DX that is his hobby

I suspect he is Sierra Oscar Lima. :(