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

On Jul 14, 7:23 pm, "Frank" wrote:
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

Has not a variometer 2 elements?

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

Has not a variometer 2 elements?

No. A variometer is simply a variable inductor.

I should also have added to the above:
Series L, Shunt L etc. etc.......

Frank

On Jul 14, 8:36 pm, "Frank" wrote:
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

Has not a variometer 2 elements?

No. A variometer is simply a variable inductor.

I should also have added to the above:
Series L, Shunt L etc. etc.......

Frank

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

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

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

Frank wrote:
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.

Other combinations can be used, for example, adjusting a transmission
line stub length and position, or a transformer in conjunction with a
reactance. The point is that an impedance has two values, commonly
expressed as R and X or as a magnitude and phase angle, so to achieve a
specific impedance requires two "degrees of freedom" -- that is, two
things which you can adjust and which, in simple terms, don't adjust
exactly the same thing. With only one adjustable element, you can get a
specific R, say, or X, but not both.

Roy Lewallen, W7EL

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