"Richard Clark" wrote in message
...
On Thu, 13 Jan 2011 16:18:35 -0600, "amdx" wrote:


The article's focus is on matching a crystal radio tank to the antenna,
So as a general statement, the tank is a high impedance (mostly R)

Hi Mike,

There's your first mistake. Tank Z is never, ever "mostly R," or you
wouldn't be able to make the Q claim of 1000 (or even 10).

Ok, Richard that wasn't clear to me, I think at resonance the tank is
all R, but I put mostly R because I figured you would have an objection to
all R. So are you saying it is pure R at resonance?

......which, then leads me to ask

"What do you really want?"

73's
Richard Clark, KB7QHC

I want to understand the use of an air variable to match an antenna
to the tank of a crystal radio, over the AMBCB frequency range.
With that, I found I need to understand the series to parallel conversion,
which I now understand, just IS, it's not anything you do. A series RC has
a parallel RC equivalent.
I'm not sure how it can be both at the same time. But as long as that R is
transformed up, and minimally loads my tank, that's all good.
Then, I understand I still have C left that I can use as part of the C for
resonating my LC tank.
Mikek

On 1/13/2011 7:51 PM, amdx wrote:
"Richard wrote in message
...
On Thu, 13 Jan 2011 16:18:35 -0600, wrote:


The article's focus is on matching a crystal radio tank to the antenna,
So as a general statement, the tank is a high impedance (mostly R)

Hi Mike,

There's your first mistake. Tank Z is never, ever "mostly R," or you
wouldn't be able to make the Q claim of 1000 (or even 10).

Ok, Richard that wasn't clear to me, I think at resonance the tank is
all R, but I put mostly R because I figured you would have an objection to
all R. So are you saying it is pure R at resonance?

......which, then leads me to ask

"What do you really want?"

73's
Richard Clark, KB7QHC

I want to understand the use of an air variable to match an antenna
to the tank of a crystal radio, over the AMBCB frequency range.
With that, I found I need to understand the series to parallel conversion,
which I now understand, just IS, it's not anything you do. A series RC has
a parallel RC equivalent.
I'm not sure how it can be both at the same time. But as long as that R is
transformed up, and minimally loads my tank, that's all good.
Then, I understand I still have C left that I can use as part of the C for
resonating my LC tank.
Mikek


You've got it now, Mike. The series/parallel equivalent circuits are
just a mathematical tool for putting things in a form you can handle
easier. Adding the capacitor does not change the circuit from series to
parallel or the other way around.

Lets say you have a fixed frequency AC source, a resistor, and a
capacitor. The R and C is in a box where you can't see how they are
wired. You measure the voltage applied to the box and measure the
current (with phase) into the box.

You could calculate the value of the R and C, right? Most people would
calculate them as an R in series with a C. But, there is a parallel R
(of a different value from the series case) and a parallel C (of a
different value) which will give the same measurements as the series
case. You cannot tell which way they are wired internally and, because
of this, you cannot tell the actual values of the components. But, for
analysis or synthesis, it won't matter.

You can mathematically change a circuit around from series (impedance)
to parallel (admittance). This is the conversion that you've been hung
up on.

Does this make any sense?

Cheers,
John

"John - KD5YI" wrote in message
...
On 1/13/2011 7:51 PM, amdx wrote:
"Richard wrote in message
...
On Thu, 13 Jan 2011 16:18:35 -0600, wrote:


The article's focus is on matching a crystal radio tank to the antenna,
So as a general statement, the tank is a high impedance (mostly R)

Hi Mike,

There's your first mistake. Tank Z is never, ever "mostly R," or you
wouldn't be able to make the Q claim of 1000 (or even 10).

Ok, Richard that wasn't clear to me, I think at resonance the tank is
all R, but I put mostly R because I figured you would have an objection
to
all R. So are you saying it is pure R at resonance?

......which, then leads me to ask

"What do you really want?"

73's
Richard Clark, KB7QHC

I want to understand the use of an air variable to match an antenna
to the tank of a crystal radio, over the AMBCB frequency range.
With that, I found I need to understand the series to parallel
conversion,
which I now understand, just IS, it's not anything you do. A series RC
has
a parallel RC equivalent.
I'm not sure how it can be both at the same time. But as long as that R
is
transformed up, and minimally loads my tank, that's all good.
Then, I understand I still have C left that I can use as part of the C
for
resonating my LC tank.
Mikek


You've got it now, Mike. The series/parallel equivalent circuits are just
a mathematical tool for putting things in a form you can handle easier.
Adding the capacitor does not change the circuit from series to parallel
or the other way around.

Lets say you have a fixed frequency AC source, a resistor, and a
capacitor. The R and C is in a box where you can't see how they are wired.
You measure the voltage applied to the box and measure the current (with
phase) into the box.

You could calculate the value of the R and C, right? Most people would
calculate them as an R in series with a C. But, there is a parallel R (of
a different value from the series case) and a parallel C (of a different
value) which will give the same measurements as the series case. You
cannot tell which way they are wired internally and, because of this, you
cannot tell the actual values of the components. But, for analysis or
synthesis, it won't matter.

You can mathematically change a circuit around from series (impedance) to
parallel (admittance). This is the conversion that you've been hung up on.

Does this make any sense?

Cheers,
John

Ya, I have a better understanding now. I need to run a few cases and
see the minimum and maximum capacitor needed for a proposed situation.
I wish it would warm up, I'd like to put up an antenna and measure it, to
get a real case to work with.
Mikek

In article ,
amdx wrote:

A series RC has
a parallel RC equivalent.

I'm not sure how it can be both at the same time.

What I found to be most instructive, in understanding this (that is,
series representations vs. parallel representations) was to drop down
a level into the underlying mathematics.

Start with the fact that you have two impedances (let's call them Z1
and Z2) which are in parallel.

Toss in the basic formula for the result:

Ztot = (Z1 * Z2) / (Z1 + Z2)

Since you have a resistor R and a capacitor C in parallel, Z1 is a
real number (it's just R), and Z2 will be an imaginary number (it's
-i/2piFC, or 1/jWC if you prefer engineering notations and squint at
the "W" so it looks like an omega).

Plug these values into the equation above, and simplify according to
the rules for complex number mathematics. You'll end up with Ztot
being a complex number, equal to the sum of a pure resistance (real)
and a pure capacitance (imaginary). These are the impedances of the
series network equivalent to your original parallel network.

Alternate route to the same solution: take each of the two impedances
and invert them, to determine the admittances of the two components.
The admittance of R will be purely real, while the admittance of C
will be purely imaginary. Add the two together (since they're in
parallel) to get the complex admittance of the parallel combination.
Now, invert this complex number according to the usual rules, to get
the equivalent complex impedance... this will be a complex number, the
sum of a pure resistance and a pure capacitance. The numbers you get
will be the same as in the previous work-through.

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

On 1/13/2011 8:33 PM, amdx wrote:

Ya, I have a better understanding now. I need to run a few cases and
see the minimum and maximum capacitor needed for a proposed situation.
I wish it would warm up, I'd like to put up an antenna and measure it, to
get a real case to work with.
Mikek



Mike -

Look into getting and learning (free) LTSpice for circuit analysis.

Also look into getting and learning EZNEC (free) for antenna analysis.

You can't beat putting up an antenna and building a circuit for it and
measuring results. But, during adverse weather, you can experiment with
simulation software and learn a lot. Then you can try your simulated
experiments when the wx is good.

Cheers,
John

On Thu, 13 Jan 2011 20:10:46 -0600, John - KD5YI
wrote:


Does this make any sense?


Up, up, and away, in my beautiful, my beautiful balun!

On Thu, 13 Jan 2011 19:51:21 -0600, "amdx" wrote:


"Richard Clark" wrote in message
.. .
On Thu, 13 Jan 2011 16:18:35 -0600, "amdx" wrote:


The article's focus is on matching a crystal radio tank to the antenna,
So as a general statement, the tank is a high impedance (mostly R)

Hi Mike,

There's your first mistake. Tank Z is never, ever "mostly R," or you
wouldn't be able to make the Q claim of 1000 (or even 10).

Ok, Richard that wasn't clear to me, I think at resonance the tank is
all R, but I put mostly R because I figured you would have an objection to
all R. So are you saying it is pure R at resonance?

Hi Mike,

Let's say there is absolutely no loss in the Tank (superconduction and
perfect dissipation values as it were); then we would have to ask
ourselves what happens to energy applied to this Tank at resonance? It
can never enter it, thus the Tank is, in effect, infinite in
resistance. But what about the circulating currents? The Tank is, in
effect, infinite in conductance.

Infinite Ohms & Zero Ohms simultaneously.

Is this the Z of the Tank? Is this the R of the Tank to which you are
matching? No, not even close and certainly it has nothing to do with
resonance - except the condition is a function of it being at
resonance. A low Z Tank or a high Z Tank each evidences the same
Infinite Ohms & Zero Ohms simultaneity given my initial condition of
absolute losslessness.

For the energy being applied to or drawn from the Tank, the Tank is in
parallel operation. For energy in the Tank, the Tank is in series
operation. Where is the Q in this duality? Q suffers by the nature
of what you call R. Q has two different values by this duality. One
is called "Loaded Q" and as you might guess, the second is called
"Unloaded Q." Consult Terman for the engineering design rationale for
optimal Qs as I suggested.

When the discussion of "matching" seeks to employ R (pure resistance),
then the next step is toward a conjugate match and elaborations of
efficiency and maximum transfer of power. There is also an
alternative discussion called the Zo Match. This second match seems
to invite the same elaborations (many who post here try to force them
both into the same salad bowl and cover the illogic with dressing).

When you offered the comment about "the tank is a high impedance
(mostly R)" it was steering the car off the cliff. Is this a Zo match
or a Conjugate match you are seeking? (I can already anticipate this
has gone over your head, as well as many readers. This and the
questions that follow are rhetorical.)

For instance, and returning to antennas (the purpose of this group's
discussion focus), you can have very high Z antennas with very low
resistance characteristics. Do you want a Zo Match, or a Conjugate
Match? Let me flip the antenna: you can have very high Z antennas
with very high resistance characteristics. Do you want a Zo Match, or
a Conjugate Match? Let's do this sideways: you can have very low Z
antennas with very low resistance characteristics. Do you want a Zo
Match, or a Conjugate Match? I could box the compass here, but the I
think I will let the reader off.


......which, then leads me to ask

"What do you really want?"

73's
Richard Clark, KB7QHC

I want to understand the use of an air variable to match an antenna
to the tank of a crystal radio, over the AMBCB frequency range.
With that, I found I need to understand the series to parallel conversion,
which I now understand, just IS, it's not anything you do. A series RC has
a parallel RC equivalent.
I'm not sure how it can be both at the same time. But as long as that R is
transformed up, and minimally loads my tank, that's all good.
Then, I understand I still have C left that I can use as part of the C for
resonating my LC tank.
Mikek

John had some number issues with Tony's explanation, but the gist of
Tony's rational treatment should be your lesson as it provides for
your requested "why." It also implies (by my comments of the sudden
appearance of two new components) that our (Ham) tuners have been
designed to introduce the proper amounts of reactances in the proper
parallel/series relationships to enable the necessary transform
towards optimal Q and loading balance. The most elaborate of tuners
can change from Pi to T topologies, or series L parallel C (or series
C parallel L), or series LC, or parallel LC, or parallel C series L
(or parallel L series C)... and any of the other combinations I have
not enumerated (about 9 in all). Each shines for a particular
situation - you have named only one.

It is not a trivial discussion by any means even when we are talking
about the addition of only two new components. So, your obtaining an
understanding is not going to be achieved at one sitting in front of
the "definitive" posting to a thread.

One problem of seeking the "definitive" posting is that it cannot be
born from a broken premise that article you were trying to figure out
is lame in the extreme. Given everything you have revealed about it,
it didn't present a solution to its fantasy antenna. That is why this
work of fiction is not understandable.

73's
Richard Clark, KB7QHC

On Thu, 13 Jan 2011 21:43:55 -0800, GoldIntermetallicEmbrittlement
g wrote:

On Thu, 13 Jan 2011 20:10:46 -0600, John - KD5YI
wrote:


Does this make any sense?


Up, up, and away, in my beautiful, my beautiful balun!

That's even worse than your favourite. You know, the one that goes
"Your mother should be arrested for ......"

**** off, you pathetic dullard.

On Jan 14, 2:33*am, "amdx" wrote:
"John - KD5YI" wrote in ...

On 1/13/2011 7:51 PM, amdx wrote:
"Richard *wrote in message
. ..
On Thu, 13 Jan 2011 16:18:35 -0600, *wrote:

The article's focus is on matching a crystal radio tank to the antenna,
So as a general statement, the tank is a high impedance (mostly R)

Hi Mike,

There's your first mistake. *Tank Z is never, ever "mostly R," or you
wouldn't be able to make the Q claim of 1000 (or even 10).

* Ok, *Richard that wasn't clear to me, I think at resonance the tank is
all R, but I put mostly R because I figured you would have an objection
to
all R. So are you saying it is pure R at resonance?

......which, then leads me to ask

"What do you really want?"

73's
Richard Clark, KB7QHC

* I want to understand the use of an air variable to match an antenna
to the tank of a crystal radio, over the AMBCB frequency range.
* With that, I found I need to understand the series to parallel
conversion,
which I now understand, just IS, it's not anything you do. A series RC
has
a parallel RC equivalent.
I'm not sure how it can be both at the same time. But as long as that R
is
transformed up, and minimally loads my tank, that's all good.
Then, I understand I still have C left that I can use as part of the C
for
resonating my LC tank.
* * * * * * * * * * Mikek

You've got it now, Mike. The series/parallel equivalent circuits are just
a mathematical tool for putting things in a form you can handle easier.
Adding the capacitor does not change the circuit from series to parallel
or the other way around.

Lets say you have a fixed frequency AC source, a resistor, and a
capacitor. The R and C is in a box where you can't see how they are wired.
You measure the voltage applied to the box and measure the current (with
phase) into the box.

You could calculate the value of the R and C, right? Most people would
calculate them as an R in series with a C. But, there is a parallel R (of
a different value from the series case) and a parallel C (of a different
value) which will give the same measurements as the series case. You
cannot tell which way they are wired internally and, because of this, you
cannot tell the actual values of the components. But, for analysis or
synthesis, it won't matter.

You can mathematically change a circuit around from series (impedance) to
parallel (admittance). This is the conversion that you've been hung up on.

Does this make any sense?

Cheers,
John

*Ya, I have a better understanding now. I need to run a few cases and
see the minimum and maximum capacitor needed for a proposed situation.
* I wish it would warm up, I'd like to put up an antenna and measure it, to
get a real case to work with.
* * * * * * * * * * * * * * * * * *Mikek

just throw a wire out the window, plug it in, and see if it works!
ANY antenna connected with a hunk of hookup wire will work better than
NO antenna with a perfectly designed match!

Ahh....1 should have said Series to Parallel Conversion.

Mikek






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