Understanding Variometer
 

In general terms.
Can we say that the variance
of an inductance containing a variometer
is zero to twice the inductance of the rotatable?
The variometer is not talked about much these days
so it is difficult to determine if something
else is at play other than what apears obvious.
I use such a set up in a coupling situation
together with variable physical separation to
prevent kickback and interference from tail
end unused inductance
I am not knoweledgeable enough to understand
all the possible implications so the variometer
seems the best place to start
Regards
Art

"Art Unwin wrote
In general terms.
Can we say that the variance
of an inductance containing a variometer
is zero to twice the inductance of the rotatable?
The variometer is not talked about much these days
so it is difficult to determine if something
else is at play other than what apears obvious.
I use such a set up in a coupling situation
together with variable physical separation to
prevent kickback and interference from tail
end unused inductance
I am not knoweledgeable enough to understand
all the possible implications so the variometer
seems the best place to start.

====================================

The inductance of the two identical coils in series is FOUR times the
inductance of a single coil provided the coupling coefficient between the
two coils approaches unity. It never does.

The main disadvantage of a variometer in a tuned circuit is that as the
mutual coupling and resulting inductance is reduced then the amount of wire
in use remains constant. So the loss resistance remains relatively
constant. And so a VERY low Q occurs at small values of inductance.

No good when used in antenna tuners. Which is great pity. The motion of one
coil rotating inside the other is beautiful to see.
----
Reg, G4FGQ

"Reg Edwards" wrote in message ...
"Art Unwin wrote
In general terms.
Can we say that the variance
of an inductance containing a variometer
is zero to twice the inductance of the rotatable?
The variometer is not talked about much these days
so it is difficult to determine if something
else is at play other than what apears obvious.
I use such a set up in a coupling situation
together with variable physical separation to
prevent kickback and interference from tail
end unused inductance
I am not knoweledgeable enough to understand
all the possible implications so the variometer
seems the best place to start.

====================================


Reg I was not looking just for an answer but better
understanding.
Your 'four times' comment just adds to my confusion.
Are you suggesting that the variometer can cancel
existing inuctance leaving just capacitance?
I suppose that would be one way to increase the variance
that you refer to..
On the subject of tuners, use of the varometer does not
become a efficiency or resistance problem when used in
antenna construction as the relationship of d.c.resisrance
Regards
Art

Note that my net listing is only updated a couple of times
per day so if there are other responses I have yet to see
them so no offence is intended.
I understand that the slowness in updating of the net does
not occur in some places in the U.S.since many responces
appear in concert with the initial posting!


to radiation resistance comes into play.



The inductance of the two identical coils in series is FOUR times the
inductance of a single coil provided the coupling coefficient between the
two coils approaches unity. It never does.

The main disadvantage of a variometer in a tuned circuit is that as the
mutual coupling and resulting inductance is reduced then the amount of wire
in use remains constant. So the loss resistance remains relatively
constant. And so a VERY low Q occurs at small values of inductance.

No good when used in antenna tuners. Which is great pity. The motion of one
coil rotating inside the other is beautiful to see.
----
Reg, G4FGQ

Art Unwin, KB9MZ wrote:
"Are you suggesting that the variometer---?"

I can`t say what Reg had in mind. What he wrote speaks for itself. The
change in mutual inductance between variometer coils causes a change in
their total inductance. As the sense of the rotatable coil can be
reversed, its inductance can be arranged to aid or oppose the inductance
of the fixed coil.

Terman says on page 20 of his 1955 edition:
"when two coils of inductance L1 and L2 , between which a mutual
inductance exists, are connected in series, the equivalent inductance of
the combination is L1 + L2 plus or minus 2M. The term 2M takes into
account the flux linkages in each coil due to the current in the other
coil. These mutual linkages may add to or subtract from the
self-linkages, depending upon the relative direction in which the
current passes through the two coils. Thus , when all linkages are in
the same direction, the total inductance of the series combination
excedes by 2M the sum of the individual inductances of the two coils."

I think Reg gave a reasonable answer. We may assume coupling (mutual
inductance) is high and that the coils are wound for equal inductances.

Now a short-cut. We know that inductance increases with the square of
the turns under common conditions. If we double the number of turns by
sensing the coils so they aid, we will quadruple the inductance, as Reg
said if I recall correctly.

Best regards, Richard Harrison, KB5WZI

I am not knoweledgeable enough to understand
all the possible implications

--------------------------------------------------

And there it is best to end the matter.

Thanks Richard
Your explanation does make sense in that I was looking at
it as several inductors but forgetting the interaction
via coupling.
May I lean on you for further help and education ?
The variometer that I have is a commercial one
and marked 3600-5000 Kc, what ever that means
and the outer windings consist of ten turns on either side
of center.
To make the inductance larger i replicated the original
outer turns so that there is now thirty turns either side
of center.( I added twenty homebrew turns either side to
the original commercial version )
Could you share with me a method of approximating the total
inductance together with its variance values?
Any help would be appreciated.
Regards
Art


(Richard Harrison) wrote in message ...
Art Unwin, KB9MZ wrote:
"Are you suggesting that the variometer---?"

I can`t say what Reg had in mind. What he wrote speaks for itself. The
change in mutual inductance between variometer coils causes a change in
their total inductance. As the sense of the rotatable coil can be
reversed, its inductance can be arranged to aid or oppose the inductance
of the fixed coil.

Terman says on page 20 of his 1955 edition:
"when two coils of inductance L1 and L2 , between which a mutual
inductance exists, are connected in series, the equivalent inductance of
the combination is L1 + L2 plus or minus 2M. The term 2M takes into
account the flux linkages in each coil due to the current in the other
coil. These mutual linkages may add to or subtract from the
self-linkages, depending upon the relative direction in which the
current passes through the two coils. Thus , when all linkages are in
the same direction, the total inductance of the series combination
excedes by 2M the sum of the individual inductances of the two coils."

I think Reg gave a reasonable answer. We may assume coupling (mutual
inductance) is high and that the coils are wound for equal inductances.

Now a short-cut. We know that inductance increases with the square of
the turns under common conditions. If we double the number of turns by
sensing the coils so they aid, we will quadruple the inductance, as Reg
said if I recall correctly.

Best regards, Richard Harrison, KB5WZI

Build the little circuit shown at:

http://www.discovercircuits.com/PDF-...arallelosc.PDF

If you measure the frequency range over which the circuit oscillates,
you can calculate the inductance range of your variometer.

73 Jim AC6XG

Art Unwin KB9MZ wrote:

Thanks Richard
Your explanation does make sense in that I was looking at
it as several inductors but forgetting the interaction
via coupling.
May I lean on you for further help and education ?
The variometer that I have is a commercial one
and marked 3600-5000 Kc, what ever that means
and the outer windings consist of ten turns on either side
of center.
To make the inductance larger i replicated the original
outer turns so that there is now thirty turns either side
of center.( I added twenty homebrew turns either side to
the original commercial version )
Could you share with me a method of approximating the total
inductance together with its variance values?
Any help would be appreciated.
Regards
Art

(Richard Harrison) wrote in message ...
Art Unwin, KB9MZ wrote:
"Are you suggesting that the variometer---?"

I can`t say what Reg had in mind. What he wrote speaks for itself. The
change in mutual inductance between variometer coils causes a change in
their total inductance. As the sense of the rotatable coil can be
reversed, its inductance can be arranged to aid or oppose the inductance
of the fixed coil.

Terman says on page 20 of his 1955 edition:
"when two coils of inductance L1 and L2 , between which a mutual
inductance exists, are connected in series, the equivalent inductance of
the combination is L1 + L2 plus or minus 2M. The term 2M takes into
account the flux linkages in each coil due to the current in the other
coil. These mutual linkages may add to or subtract from the
self-linkages, depending upon the relative direction in which the
current passes through the two coils. Thus , when all linkages are in
the same direction, the total inductance of the series combination
excedes by 2M the sum of the individual inductances of the two coils."

I think Reg gave a reasonable answer. We may assume coupling (mutual
inductance) is high and that the coils are wound for equal inductances.

Now a short-cut. We know that inductance increases with the square of
the turns under common conditions. If we double the number of turns by
sensing the coils so they aid, we will quadruple the inductance, as Reg
said if I recall correctly.

Best regards, Richard Harrison, KB5WZI

Richard,
On reflection I now see that how a variometer is
connected up can make a big difference.
In my particular case all coils are connected in
series such that the current is constant thru out.
An alternative way of connecting a variometer I suppose
is to supply a different current or placing the revolvable
inductance as part of another separate circuit whereas the
COUPLING action alone will provide the variances you speak of.
As for adding inductances in series, as stated in my earlier
reply, is a lot different such that I now believe my
original analysis is correct.( In other words I have just
increased the number of turns by sliding the inductances
together to make one inductor leaving the third inductor
which is revolveable seen as an inductance with reversable
turns or flux pattern.)
As you probably can now see I am totally confused,
especially since this arrangement is then coupled
to another separate circuit which is where I suspect the
+ or - 'M' variation comes into play comes into play.
Regards
Art
Regards
Art


(Richard Harrison) wrote in message ...
Art Unwin, KB9MZ wrote:
"Are you suggesting that the variometer---?"

I can`t say what Reg had in mind. What he wrote speaks for itself. The
change in mutual inductance between variometer coils causes a change in
their total inductance. As the sense of the rotatable coil can be
reversed, its inductance can be arranged to aid or oppose the inductance
of the fixed coil.

Terman says on page 20 of his 1955 edition:
"when two coils of inductance L1 and L2 , between which a mutual
inductance exists, are connected in series, the equivalent inductance of
the combination is L1 + L2 plus or minus 2M. The term 2M takes into
account the flux linkages in each coil due to the current in the other
coil. These mutual linkages may add to or subtract from the
self-linkages, depending upon the relative direction in which the
current passes through the two coils. Thus , when all linkages are in
the same direction, the total inductance of the series combination
excedes by 2M the sum of the individual inductances of the two coils."

I think Reg gave a reasonable answer. We may assume coupling (mutual
inductance) is high and that the coils are wound for equal inductances.

Now a short-cut. We know that inductance increases with the square of
the turns under common conditions. If we double the number of turns by
sensing the coils so they aid, we will quadruple the inductance, as Reg
said if I recall correctly.

Best regards, Richard Harrison, KB5WZI

Art Unwin, KB9MZ wrote:
"Could you share with me a method of approximating the total inductance
together with its variance values?"

The design of shortwave coils is a complicated process. Skin effect
causes most loss, and single-strand wire wound as a single-layer coil is
usually best. According to Terman, the highest Q is usually, for a given
sized coil, gotten by a winding length somewhat less than the diameter
of the coil. Terman refers to an article in "Wireless Eng.", vol. 26,
page 179, June 1949 by G.W.O. Howe.

My big help with coils comes from the ARRL "L/C/F Calcululator", a
specialized slide-rule. My "Model A" has a price of $2.00 printed on it.

Tom Bruhns has done a lot of work with coils and knows much more about
them than I do. Maybe he will offer some help.

Reg has studied the pertinent factors and used them for some of his
marvelous programs, so he can be a big help.

Sorry I am not qualified to be much help. My method has been "cut and
try".

I was reading an excellent article from a 1920 QST as reprinted in
January 1966, by E.H. Armstrong about his Signal Corps research in WW-1.
He noted that his IF transformers benefitted from many turns of fine
wire which reduced capacitance and added enough resistance to dampen
oscillation tendencies. Armstrong was using "Type 5" triodes in his IF
amplifier of 100 KHz. I am sorry that I am so out of date.

Best regards, Richard Harrison, KB5WZI

Hi Art,
the connection "all in series" is the proper one, not "particular".
Usually there are four parts of winding: one half of fixed coil, two
halves of moving coil and another half of fixed coil. Let's mark the
fixed coil inductance L1 and the moving coil L2. The construction is
made so that L1=L2 and magnetic coupling is as tight as possible. The
mutual inductance when both coils have the same axis is therefore
approximately M=L1=L2.
If the moving coil is turned so that the magnetic fields add, the
total inductance is (nearly) L = L1+L2+2M = 4*L1.
If the moving coil is turned so it is perpendicular to the fixed one
and the magnetic fields do not influence the other coil, the mutual
inductance is zero and the total inductance is L = L1+L2 = 2*L1.
If the moving coil is turned so that the magnetic fields subtract, the
total inductance is (nearly) L = L1+L2-2M = 0.
When you added some turns, you destroyed the construction symmetry.
Measuring the total inductance at various coil positions within 0..180
deg and at the working frequecy is the best you can do.

Variometers are often used for tuning antennas at 136 kHz. See
http://www.sweb.cz/ok1fig/Small_vario.jpg ,
http://www.sweb.cz/ok1fig/Big_vario_02.jpg ,
http://www.sweb.cz/ok1fig/Big_vario_03.jpg or
http://www.g0mrf.freeserve.co.uk/variometer.htm .

BR from Ivan


(Art Unwin KB9MZ) wrote in message om...
Richard,
On reflection I now see that how a variometer is
connected up can make a big difference.
In my particular case all coils are connected in
series such that the current is constant thru out.
An alternative way of connecting a variometer I suppose
is to supply a different current or placing the revolvable
inductance as part of another separate circuit whereas the
COUPLING action alone will provide the variances you speak of.
As for adding inductances in series, as stated in my earlier
reply, is a lot different such that I now believe my
original analysis is correct.( In other words I have just
increased the number of turns by sliding the inductances
together to make one inductor leaving the third inductor
which is revolveable seen as an inductance with reversable
turns or flux pattern.)
As you probably can now see I am totally confused,
especially since this arrangement is then coupled
to another separate circuit which is where I suspect the
+ or - 'M' variation comes into play comes into play.
Regards
Art

On 9 Oct 2003 23:39:07 -0700, (OK1SIP) wrote:
Variometers are often used for tuning antennas at 136 kHz. See
http://www.sweb.cz/ok1fig/Small_vario.jpg ,
http://www.sweb.cz/ok1fig/Big_vario_02.jpg ,
http://www.sweb.cz/ok1fig/Big_vario_03.jpg or
http://www.g0mrf.freeserve.co.uk/variometer.htm .

BR from Ivan

Hi Ivan,

Those are some great variometers.

73's
Richard Clark, KB7QHC

Richard.
You have no need to be sorry!
\You are trying to help me and
I appreciate that.
My problem started when I moved
away from a homebrew coil on a circuit
which was coupled to a rod ( distributed inductance)
The coupled rod when moved allowed for
an ideal matching setup
as it could be made into a perfect match
for top band use.( the rod was the driven element)
When I substituted a variometer for fine
tuning everything went to pot!
(That is why they call mesh circuits 'complex' )
Thus the questions regarding variometers
and the markings. With the new band in
the U.K. being used I suspect we are going
to hear a lot more about this instrument
and I can then reintroduce it on my antenna
Best regards
Art




(Richard Harrison) wrote in message ...
Art Unwin, KB9MZ wrote:
"Could you share with me a method of approximating the total inductance
together with its variance values?"

The design of shortwave coils is a complicated process. Skin effect
causes most loss, and single-strand wire wound as a single-layer coil is
usually best. According to Terman, the highest Q is usually, for a given
sized coil, gotten by a winding length somewhat less than the diameter
of the coil. Terman refers to an article in "Wireless Eng.", vol. 26,
page 179, June 1949 by G.W.O. Howe.

My big help with coils comes from the ARRL "L/C/F Calcululator", a
specialized slide-rule. My "Model A" has a price of $2.00 printed on it.

Tom Bruhns has done a lot of work with coils and knows much more about
them than I do. Maybe he will offer some help.

Reg has studied the pertinent factors and used them for some of his
marvelous programs, so he can be a big help.

Sorry I am not qualified to be much help. My method has been "cut and
try".

I was reading an excellent article from a 1920 QST as reprinted in
January 1966, by E.H. Armstrong about his Signal Corps research in WW-1.
He noted that his IF transformers benefitted from many turns of fine
wire which reduced capacitance and added enough resistance to dampen
oscillation tendencies. Armstrong was using "Type 5" triodes in his IF
amplifier of 100 KHz. I am sorry that I am so out of date.

Best regards, Richard Harrison, KB5WZI

What a great posting!
The input and work has not gone unnoticed
and I am sure that all on the net appreciate
your presence. I need time to digest it as I
am now in a state of confusion regarding the subject
and its applicability to my particular project.
Many, many thanks for your effort
Art





(OK1SIP) wrote in message . com...
Hi Art,
the connection "all in series" is the proper one, not "particular".
Usually there are four parts of winding: one half of fixed coil, two
halves of moving coil and another half of fixed coil. Let's mark the
fixed coil inductance L1 and the moving coil L2. The construction is
made so that L1=L2 and magnetic coupling is as tight as possible. The
mutual inductance when both coils have the same axis is therefore
approximately M=L1=L2.
If the moving coil is turned so that the magnetic fields add, the
total inductance is (nearly) L = L1+L2+2M = 4*L1.
If the moving coil is turned so it is perpendicular to the fixed one
and the magnetic fields do not influence the other coil, the mutual
inductance is zero and the total inductance is L = L1+L2 = 2*L1.
If the moving coil is turned so that the magnetic fields subtract, the
total inductance is (nearly) L = L1+L2-2M = 0.
When you added some turns, you destroyed the construction symmetry.
Measuring the total inductance at various coil positions within 0..180
deg and at the working frequecy is the best you can do.

Variometers are often used for tuning antennas at 136 kHz. See
http://www.sweb.cz/ok1fig/Small_vario.jpg ,
http://www.sweb.cz/ok1fig/Big_vario_02.jpg ,
http://www.sweb.cz/ok1fig/Big_vario_03.jpg or
http://www.g0mrf.freeserve.co.uk/variometer.htm .

BR from Ivan


(Art Unwin KB9MZ) wrote in message om...
Richard,
On reflection I now see that how a variometer is
connected up can make a big difference.
In my particular case all coils are connected in
series such that the current is constant thru out.
An alternative way of connecting a variometer I suppose
is to supply a different current or placing the revolvable
inductance as part of another separate circuit whereas the
COUPLING action alone will provide the variances you speak of.
As for adding inductances in series, as stated in my earlier
reply, is a lot different such that I now believe my
original analysis is correct.( In other words I have just
increased the number of turns by sliding the inductances
together to make one inductor leaving the third inductor
which is revolveable seen as an inductance with reversable
turns or flux pattern.)
As you probably can now see I am totally confused,
especially since this arrangement is then coupled
to another separate circuit which is where I suspect the
+ or - 'M' variation comes into play comes into play.
Regards
Art

Before this thread bites the dust
Can anyone point out the meanings of the markings
on my commercial variometer?
The markings are

3600-5000KC

Thanks in advance
Art





(Art Unwin KB9MZ) wrote in message om...
What a great posting!
The input and work has not gone unnoticed
and I am sure that all on the net appreciate
your presence. I need time to digest it as I
am now in a state of confusion regarding the subject
and its applicability to my particular project.
Many, many thanks for your effort
Art





(OK1SIP) wrote in message . com...
Hi Art,
the connection "all in series" is the proper one, not "particular".
Usually there are four parts of winding: one half of fixed coil, two
halves of moving coil and another half of fixed coil. Let's mark the
fixed coil inductance L1 and the moving coil L2. The construction is
made so that L1=L2 and magnetic coupling is as tight as possible. The
mutual inductance when both coils have the same axis is therefore
approximately M=L1=L2.
If the moving coil is turned so that the magnetic fields add, the
total inductance is (nearly) L = L1+L2+2M = 4*L1.
If the moving coil is turned so it is perpendicular to the fixed one
and the magnetic fields do not influence the other coil, the mutual
inductance is zero and the total inductance is L = L1+L2 = 2*L1.
If the moving coil is turned so that the magnetic fields subtract, the
total inductance is (nearly) L = L1+L2-2M = 0.
When you added some turns, you destroyed the construction symmetry.
Measuring the total inductance at various coil positions within 0..180
deg and at the working frequecy is the best you can do.

Variometers are often used for tuning antennas at 136 kHz. See
http://www.sweb.cz/ok1fig/Small_vario.jpg ,
http://www.sweb.cz/ok1fig/Big_vario_02.jpg ,
http://www.sweb.cz/ok1fig/Big_vario_03.jpg or
http://www.g0mrf.freeserve.co.uk/variometer.htm .

BR from Ivan


(Art Unwin KB9MZ) wrote in message om...
Richard,
On reflection I now see that how a variometer is
connected up can make a big difference.
In my particular case all coils are connected in
series such that the current is constant thru out.
An alternative way of connecting a variometer I suppose
is to supply a different current or placing the revolvable
inductance as part of another separate circuit whereas the
COUPLING action alone will provide the variances you speak of.
As for adding inductances in series, as stated in my earlier
reply, is a lot different such that I now believe my
original analysis is correct.( In other words I have just
increased the number of turns by sliding the inductances
together to make one inductor leaving the third inductor
which is revolveable seen as an inductance with reversable
turns or flux pattern.)
As you probably can now see I am totally confused,
especially since this arrangement is then coupled
to another separate circuit which is where I suspect the
+ or - 'M' variation comes into play comes into play.
Regards
Art

I would assume it means that the tuning range was 3.6 MHz to 5.0 MHz
(3600 kHz or kc to 5000 kHz)

Mark

--
On 11 Oct 2003 17:10:20 -0700, (Art Unwin KB9MZ)
wrote:

Before this thread bites the dust
Can anyone point out the meanings of the markings
on my commercial variometer?
The markings are

3600-5000KC

Thanks in advance
Art





(Art Unwin KB9MZ) wrote in message om...
What a great posting!
The input and work has not gone unnoticed
and I am sure that all on the net appreciate
your presence. I need time to digest it as I
am now in a state of confusion regarding the subject
and its applicability to my particular project.
Many, many thanks for your effort
Art





(OK1SIP) wrote in message . com...
Hi Art,
the connection "all in series" is the proper one, not "particular".
Usually there are four parts of winding: one half of fixed coil, two
halves of moving coil and another half of fixed coil. Let's mark the
fixed coil inductance L1 and the moving coil L2. The construction is
made so that L1=L2 and magnetic coupling is as tight as possible. The
mutual inductance when both coils have the same axis is therefore
approximately M=L1=L2.
If the moving coil is turned so that the magnetic fields add, the
total inductance is (nearly) L = L1+L2+2M = 4*L1.
If the moving coil is turned so it is perpendicular to the fixed one
and the magnetic fields do not influence the other coil, the mutual
inductance is zero and the total inductance is L = L1+L2 = 2*L1.
If the moving coil is turned so that the magnetic fields subtract, the
total inductance is (nearly) L = L1+L2-2M = 0.
When you added some turns, you destroyed the construction symmetry.
Measuring the total inductance at various coil positions within 0..180
deg and at the working frequecy is the best you can do.

Variometers are often used for tuning antennas at 136 kHz. See
http://www.sweb.cz/ok1fig/Small_vario.jpg ,
http://www.sweb.cz/ok1fig/Big_vario_02.jpg ,
http://www.sweb.cz/ok1fig/Big_vario_03.jpg or
http://www.g0mrf.freeserve.co.uk/variometer.htm .

BR from Ivan


(Art Unwin KB9MZ) wrote in message om...
Richard,
On reflection I now see that how a variometer is
connected up can make a big difference.
In my particular case all coils are connected in
series such that the current is constant thru out.
An alternative way of connecting a variometer I suppose
is to supply a different current or placing the revolvable
inductance as part of another separate circuit whereas the
COUPLING action alone will provide the variances you speak of.
As for adding inductances in series, as stated in my earlier
reply, is a lot different such that I now believe my
original analysis is correct.( In other words I have just
increased the number of turns by sliding the inductances
together to make one inductor leaving the third inductor
which is revolveable seen as an inductance with reversable
turns or flux pattern.)
As you probably can now see I am totally confused,
especially since this arrangement is then coupled
to another separate circuit which is where I suspect the
+ or - 'M' variation comes into play comes into play.
Regards
Art

Art Unwin, KB9MZ wrote:
"The markings are 3600 - 5000 KC."

"KC" may date the variometer back several decades or more.

Inductance has units of flux linkages per amp.

A single-layer solenoid has an inductance in microhenries of:
L = (n squared) (d) (form factor)
n = number of turns
d = diameter of the coil
form factor = complicated constant that depends on the length to
diameter ratio

See Terman`s 1955 edition, page 11 for the inductance story.

Inductance does not have a frequency term in its formula, but inductive
reactance is proportional to frrequency.

I guess that the variometer`s frequency markings are related to Q.
Resistance rises as the sq rt of frequency due to skin effect. Q will be
inversely proportional to r-f resistance in a coil.

As Reg Edwards has already said, a variometer`s Q is likely very poor
when set for low inductance. Q is XL/R.

Changing the variometer`s inductance setting has almost no effect on its
resistance. Its Q will be low enough at maximum inductance setting on a
shortwave variometer. Lower XL and don`t change the R. The effect on Q
is obvious.

I suspect the variometer was optimized for Q in the 3600 - 5000 MHz
range.

Best regards, Richard Harrison, KB5WZI

Art Unwin, KB9MZ wrote:
"The markings are 3600 - 5000 KC."




It was used in a radio or transmitter operating in that range. (German WW II
SK10?)

Yuri

On 12 Oct 2003 03:24:10 GMT, oSaddam (Yuri Blanarovich)
wrote:

Art Unwin, KB9MZ wrote:
"The markings are 3600 - 5000 KC."
It was used in a radio or transmitter operating in that range. (German WW II
SK10?)

Yuri

Hi Yuri,

More probable is Marine DF.

73's
Richard Clark, KB7QHC

Richard Clark wrote in message . ..
On 12 Oct 2003 03:24:10 GMT, oSaddam (Yuri Blanarovich)
wrote:

Art Unwin, KB9MZ wrote:
"The markings are 3600 - 5000 KC."
It was used in a radio or transmitter operating in that range. (German WW II
SK10?)

Yuri

Hi Yuri,

More probable is Marine DF.

73's
Richard Clark, KB7QHC

After digging into this subject so that I fully understand it I found
that this particular antenna did not work as it should have done. This
'dummy' assumed that I could obtain any Q that I wanted, however
actual inductor was very inefficient for top band use ( very
broadbanded because of losses.)
I went from 4 inch diameter inductance windings to
a 12 inch o/a diameter with 0.6, O.D. copper tubing for a total length
for the inductor of 35 inches. My intention is to now flatten the
copper tubing so the edges to provide minimum interwinding
capacitance.
However I do want the maximum Q available so the antenna is narrow
banded and inductance change is made by lessening the inductance
length for moving around the band.( or possibly the insertion of a
brass rod)

What other options do I have for increasing Q other than silver
plating of the copper?
I opted away from LITZ wire as I figured that top band was too
high a frequency to benefit from its properties.
Any comments or discussion of the subject would be very apreciated
Best regards
Art

On 19 Oct 2003 16:49:23 -0700, (Art Unwin KB9MZ)
wrote:

What other options do I have for increasing Q other than silver
plating of the copper?

Hi Art,

Make it as small as possible, with as large as possible conductors.
Look at any of the small, tunable, loop antennas on the market.

As a bonus, you also get to participate in the eternal debate about
the voltage found at the ends of a dipole when your own construction
begins arcing big time.

73's
Richard Clark, KB7QHC

Art Unwin, KB9MZ wrote:
"What other options do I have for increasing Q other than silver plating
of the copper?"

Art has access to yhe 1955 edition of Terman`s "Electronics and Radio
Engineering", I believe. On page 32 Terman writes:
"In designing single-layer coils, the highest Q in proportion to size is
obtained when the length of the winding is somewhat less than the
diameter of the coil."

It appears Art went in the right direction by increasing the coil
diameter to 12 inches from 4 inches. Nonetheless, his coil is 35 inches
long.

If Art doesn`t want to use a high permeability core, and his coil
already has the required inductance, it seems fewer turns on a larger
diameter form would have a higher Q, so the length of the coil can be
less than the diameter of the coil for the same inductance.

It is good to space the turns by about the diameter of the conductor, or
slightly less. Insulation can be lossy and tends to rise in loss by the
cube of the frequency, so Terman warns about cotton or enamel covered
wire and insulating material used in coil forms at high frequencies. See
page 35 in his 1955 edition.

The existing coil can be measured for inductance, if it is right, and a
coil calculator or program can be consulted to get a coil with better
proportions.

To tune a circuit, a variable capacitor may maintain a better Q than a
variable inductance, (variometer) but at 160 meters, permeability tuning
of the coil should be practical if the power level isn`t too high.

Best regards, Richard Harrison, KB5WZI

If both coil diameter and length are doubled, and number of turns are
reduced to 71% of the number you started with, then you will end-up with the
same inductance as before but the loss resistance will be 71% smaller.

You can continue to do this until radiation resistance becomes the
predominant loss.

Download program SOLNOID2 for coil design and to study these effects.
--
=======================
Regards from Reg, G4FGQ
For Free Radio Design Software
go to http://www.g4fgq.com
=======================


"Art Unwin KB9MZ" wrote in message
...
Richard Clark wrote in message
. ..
On 12 Oct 2003 03:24:10 GMT, oSaddam (Yuri Blanarovich)
wrote:

Art Unwin, KB9MZ wrote:
"The markings are 3600 - 5000 KC."
It was used in a radio or transmitter operating in that range. (German
WW II
SK10?)

Yuri

Hi Yuri,

More probable is Marine DF.

73's
Richard Clark, KB7QHC

After digging into this subject so that I fully understand it I found
that this particular antenna did not work as it should have done. This
'dummy' assumed that I could obtain any Q that I wanted, however
actual inductor was very inefficient for top band use ( very
broadbanded because of losses.)
I went from 4 inch diameter inductance windings to
a 12 inch o/a diameter with 0.6, O.D. copper tubing for a total length
for the inductor of 35 inches. My intention is to now flatten the
copper tubing so the edges to provide minimum interwinding
capacitance.
However I do want the maximum Q available so the antenna is narrow
banded and inductance change is made by lessening the inductance
length for moving around the band.( or possibly the insertion of a
brass rod)

What other options do I have for increasing Q other than silver
plating of the copper?
I opted away from LITZ wire as I figured that top band was too
high a frequency to benefit from its properties.
Any comments or discussion of the subject would be very apreciated
Best regards
Art

Make it as small as possible, with as large as possible conductors.
===========================

Rubbish !

Richard Clark wrote in message . ..
On 19 Oct 2003 16:49:23 -0700, (Art Unwin KB9MZ)
wrote:

What other options do I have for increasing Q other than silver
plating of the copper?

Hi Art,

Make it as small as possible, with as large as possible conductors.
Look at any of the small, tunable, loop antennas on the market.

As a bonus, you also get to participate in the eternal debate about
the voltage found at the ends of a dipole when your own construction
begins arcing big time.

73's
Richard Clark, KB7QHC


Richard,
In my case I need the field around the inductance for coupling
purposes.
To make it smaller a core material would have to be used.
I spoke of flattening the tubing but I am not sure if it would
be worth it to plate or should it be wound ribbon wise as
some of the old Collins inductors or edge wise wound per some
of the commercial inductances.
Going to the large copper winding really showed up as an
improvement in the antenna such that it has wet my appetite !
Regards
Art

Art, I should have added - you must take the opportunity to increase
conductor diameter. You have twice the length of coil with only 70% of the
number of turns to wind along it.

There is NO other way to increase Q of a coil while maintaining the same
inductance.

If you think about it it's fairly obvious.
---
Reg

"Reg Edwards" wrote
If both coil diameter and length are doubled, and number of turns are
reduced to 71% of the number you started with, then you will end-up with
the
same inductance as before but the loss resistance will be 71% smaller.

You can continue to do this until radiation resistance becomes the
predominant loss.

Download program SOLNOID2 for coil design and to study these effects.
--
=======================
Regards from Reg, G4FGQ
For Free Radio Design Software
go to http://www.g4fgq.com
=======================


"Art Unwin KB9MZ" wrote in message
...
Richard Clark wrote in message
. ..
On 12 Oct 2003 03:24:10 GMT, oSaddam (Yuri Blanarovich)
wrote:

Art Unwin, KB9MZ wrote:
"The markings are 3600 - 5000 KC."
It was used in a radio or transmitter operating in that range.
(German
WW II
SK10?)

Yuri

Hi Yuri,

More probable is Marine DF.

73's
Richard Clark, KB7QHC

After digging into this subject so that I fully understand it I found
that this particular antenna did not work as it should have done. This
'dummy' assumed that I could obtain any Q that I wanted, however
actual inductor was very inefficient for top band use ( very
broadbanded because of losses.)
I went from 4 inch diameter inductance windings to
a 12 inch o/a diameter with 0.6, O.D. copper tubing for a total length
for the inductor of 35 inches. My intention is to now flatten the
copper tubing so the edges to provide minimum interwinding
capacitance.
However I do want the maximum Q available so the antenna is narrow
banded and inductance change is made by lessening the inductance
length for moving around the band.( or possibly the insertion of a
brass rod)

What other options do I have for increasing Q other than silver
plating of the copper?
I opted away from LITZ wire as I figured that top band was too
high a frequency to benefit from its properties.
Any comments or discussion of the subject would be very apreciated
Best regards
Art

On 20 Oct 2003 15:19:42 -0700, (Art Unwin KB9MZ)
wrote:
Richard,
In my case I need the field around the inductance for coupling
purposes.

The size of the field has nothing to do with Q.

To make it smaller a core material would have to be used.

Only if you want the same inductance - you didn't ask that, you asked
for more Q.

I spoke of flattening the tubing but I am not sure if it would
be worth it to plate or should it be wound ribbon wise as
some of the old Collins inductors or edge wise wound per some
of the commercial inductances.

Flattening will only increase loss - not Q.

Going to the large copper winding really showed up as an
improvement in the antenna such that it has wet my appetite !
Regards
Art

Increasing copper for the same, or near same inductance is a waste of
time. You have to have started with a pitifully poor example wound on
a old wive's sewing spool to make any gain in that game.

Start with the basic dipole's Q and reckon how much your Q will be
improved = diddly squat. Turn that basic dipole into a small tuned
loop (AKA MFJ or whoever) and watch that Q go through the roof.

However, there is one hidden negative to your wish. Q is not, of and
in itself, a positive thing when optimized beyond all other
characteristics. The crystal in an electric circuit has an
exceptionally high Q and a dipole a mediocre-to-poor one. Which
transmits HF further? If you read your Terman, you will find that
even for a transmitter's tuned final, you DO NOT want the highest Q,
but instead a value between 8 and a dozen. If it were higher, power
would never come out the antenna port.

73's
Richard Clark, KB7QHC

Rubbish !
RTMFQ!

"Reg Edwards" wrote in message ...
Art, I should have added - you must take the opportunity to increase
conductor diameter. You have twice the length of coil with only 70% of the
number of turns to wind along it.

There is NO other way to increase Q of a coil while maintaining the same
inductance.

If you think about it it's fairly obvious.

Reg
my mind is not as alert as yours, many times I will argue for what is
obvious at the time but after several days am forced to change my
mind.
This is a similar case where I am mindful of the bad effects of
capacitance
so I am heading towards keeping the same outside area but reducing
capacitance raising surfaces which by flattening the coil places
the turns closer together.
Since the coils are so large the design forces me to place one side of
the coil close to a fibre glass support which is not good either plus
if I make the turns larger and lighter it will become flimsy unless I
add dielectric loss type supports which may well overtake the losses
in the present design.
All most interesting which is forcing me to think about such a simple
thing such as inductance.
Cheers
Art

---
Reg

"Reg Edwards" wrote
If both coil diameter and length are doubled, and number of turns are
reduced to 71% of the number you started with, then you will end-up with
the
same inductance as before but the loss resistance will be 71% smaller.

You can continue to do this until radiation resistance becomes the
predominant loss.

Download program SOLNOID2 for coil design and to study these effects.
--
=======================
Regards from Reg, G4FGQ
For Free Radio Design Software
go to http://www.g4fgq.com
=======================


"Art Unwin KB9MZ" wrote in message
...
Richard Clark wrote in message
. ..
On 12 Oct 2003 03:24:10 GMT, oSaddam (Yuri Blanarovich)
wrote:

Art Unwin, KB9MZ wrote:
"The markings are 3600 - 5000 KC."
It was used in a radio or transmitter operating in that range.
(German
WW II
SK10?)

Yuri

Hi Yuri,

More probable is Marine DF.

73's
Richard Clark, KB7QHC

After digging into this subject so that I fully understand it I found
that this particular antenna did not work as it should have done. This
'dummy' assumed that I could obtain any Q that I wanted, however
actual inductor was very inefficient for top band use ( very
broadbanded because of losses.)
I went from 4 inch diameter inductance windings to
a 12 inch o/a diameter with 0.6, O.D. copper tubing for a total length
for the inductor of 35 inches. My intention is to now flatten the
copper tubing so the edges to provide minimum interwinding
capacitance.
However I do want the maximum Q available so the antenna is narrow
banded and inductance change is made by lessening the inductance
length for moving around the band.( or possibly the insertion of a
brass rod)

What other options do I have for increasing Q other than silver
plating of the copper?
I opted away from LITZ wire as I figured that top band was too
high a frequency to benefit from its properties.
Any comments or discussion of the subject would be very apreciated
Best regards
Art