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

2 elements required? What does that mean?

In most cases an inductor, and capacitor, is required to match
a complex impedance, as follows:

Shunt C, Series L;
Shunt L, Series C;
Series L, Shunt C, or;
Series C, Shunt L.

Only rarely can a single component provide a match.

73,

Frank

Art Unwin wrote:

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

There ya' go ... his response.

It appears, what he was saying was/is, you cannot obtain maximum
transfer of power to the antenna with the variometer alone--you must use
a pi/LC/etc. (a capacitance in conjunction with an inductance) ...

I re-read his post, that meaning was implied well--but I could only see
it with hindsight.

JS

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 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 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

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

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.