On 7/31/2015 1:15 AM, rickman wrote:
On 7/30/2015 10:52 PM, David Ryeburn wrote:
In article , rickman
wrote:

I can't say I agree with your "choking" impedance idea. The coax
connects to the balun in the same way it connects to the antenna.

No, it's really rather different.

You aren't explaining anything.

Now you are being argumentative, Rick. Do you want to continue the
dialog or not?

On 7/31/2015 12:19 PM, John S wrote:
On 7/31/2015 1:15 AM, rickman wrote:
On 7/30/2015 10:52 PM, David Ryeburn wrote:
In article , rickman
wrote:

I can't say I agree with your "choking" impedance idea. The coax
connects to the balun in the same way it connects to the antenna.

No, it's really rather different.

You aren't explaining anything.

Now you are being argumentative, Rick. Do you want to continue the
dialog or not?

That is BS. Saying something is "different" with no explanation is not
"discussion" and is not useful to a "dialog". I'm just pointing that out.

In fact, much of what is being said here is talking past the points I
have made. Rather than try to understand what is going on, most here
seem to just repeat the standard explanation without thinking it
through. One of the references discusses the case of a balun made by
wrapping the coax around a core, but when discussing a separate balun
made of wires they say, "When constructed of twisted-pair line, the
effect on imbalance current is the same and for the same reasons, but
operation is more difficuit to visualize". That is a cop-out. A pair
of wires is very clearly different from a coax.

Anytime you don't wish to reply to my posts you are free to refrain.

--

Rick

In article , rickman
wrote:

On 7/31/2015 12:19 PM, John S wrote:
On 7/31/2015 1:15 AM, rickman wrote:
On 7/30/2015 10:52 PM, David Ryeburn wrote:
In article , rickman
wrote:

I can't say I agree with your "choking" impedance idea. The coax
connects to the balun in the same way it connects to the antenna.

No, it's really rather different.

You aren't explaining anything.

Now you are being argumentative, Rick. Do you want to continue the
dialog or not?

Worse than argumentative. I DID explain, but I can't read for him.

I give up. Between us, his word is last. Anyone else who wishes to show
me where my argument involving resistors, Kirchhoff's law, fields inside
coaxial cables, etc. is incorrect, I'll be glad to read. I'm always
ready to learn. In the meantime I'll connect my current baluns the way
I described, and they'll work the way I described. He can do what he
wants.

David, VE7EZM (now), AF7BZ (now), and W8EZE (1949-1967)

--
David Ryeburn

To send e-mail, change "netz" to "net"

On 7/31/2015 1:55 PM, David Ryeburn wrote:
In article , rickman
wrote:

On 7/31/2015 12:19 PM, John S wrote:
On 7/31/2015 1:15 AM, rickman wrote:
On 7/30/2015 10:52 PM, David Ryeburn wrote:
In article , rickman
wrote:

I can't say I agree with your "choking" impedance idea. The coax
connects to the balun in the same way it connects to the antenna.

No, it's really rather different.

You aren't explaining anything.

Now you are being argumentative, Rick. Do you want to continue the
dialog or not?

Worse than argumentative. I DID explain, but I can't read for him.

I give up. Between us, his word is last. Anyone else who wishes to show
me where my argument involving resistors, Kirchhoff's law, fields inside
coaxial cables, etc. is incorrect, I'll be glad to read. I'm always
ready to learn. In the meantime I'll connect my current baluns the way
I described, and they'll work the way I described. He can do what he
wants.

I replied to your post in detail. The comment above was about the
single line response which was not useful. If you want to take an
attitude fine. But please don't act like I was not communicating. I
explained to you my points and now you choose to complain.

I never said baluns don't work. So your comment about your equipment is
not relevant to the discussion.

--

Rick

Jeff wrote:

I give up. Between us, his word is last. Anyone else who wishes to show
me where my argument involving resistors, Kirchhoff's law, fields inside
coaxial cables, etc. is incorrect, I'll be glad to read. I'm always
ready to learn. In the meantime I'll connect my current baluns the way
I described, and they'll work the way I described. He can do what he
wants.

Conservation of energy also shows that with a perfectly matched dipole
all of the energy applied to it will be radiated, or lost as heat in the
elements. So by extension there can be no power flowing on the coax outer.

Jeff
So, clearly, the energy supplied from the feeder and conducted down the
coax outer nerver reaches the antenna. Just as two resistors in
parallel share the energy supplied by a voltage applies across them.


--
Roger Hayter

Jeff wrote:

On 01/08/2015 10:54, Roger Hayter wrote:
Jeff wrote:

I give up. Between us, his word is last. Anyone else who wishes to show
me where my argument involving resistors, Kirchhoff's law, fields inside
coaxial cables, etc. is incorrect, I'll be glad to read. I'm always
ready to learn. In the meantime I'll connect my current baluns the way
I described, and they'll work the way I described. He can do what he
wants.

Conservation of energy also shows that with a perfectly matched dipole
all of the energy applied to it will be radiated, or lost as heat in the
elements. So by extension there can be no power flowing on the coax outer.

Jeff
So, clearly, the energy supplied from the feeder and conducted down the
coax outer nerver reaches the antenna. Just as two resistors in
parallel share the energy supplied by a voltage applies across them.



No, there will be no energy "supplied from the feeder and conducted down
the coax outer" as it will all be conducted into the antenna and
radiated if the antenna is perfectly balanced. The power flowing up the
coax, when perfectly matched, will only 'see' the antenna load, not the
coax outer as and element in parallel.

Jeff

If it was perfectly balanced before you connected the feeder, it will no
longer be perfectly balanced once the shunt impedance to earth of the
coax braid is connected to *one* side of it. Dare I say that that is
why you need a balun? This asymmetrical shunt impedance is the source
of the whole question.

--
Roger Hayter

On 8/1/2015 9:09 AM, Roger Hayter wrote:
Jeff wrote:

On 01/08/2015 10:54, Roger Hayter wrote:
Jeff wrote:

Conservation of energy also shows that with a perfectly matched dipole
all of the energy applied to it will be radiated, or lost as heat in the
elements. So by extension there can be no power flowing on the coax outer.

Jeff
So, clearly, the energy supplied from the feeder and conducted down the
coax outer nerver reaches the antenna. Just as two resistors in
parallel share the energy supplied by a voltage applies across them.



No, there will be no energy "supplied from the feeder and conducted down
the coax outer" as it will all be conducted into the antenna and
radiated if the antenna is perfectly balanced. The power flowing up the
coax, when perfectly matched, will only 'see' the antenna load, not the
coax outer as and element in parallel.

Jeff

If it was perfectly balanced before you connected the feeder, it will no
longer be perfectly balanced once the shunt impedance to earth of the
coax braid is connected to *one* side of it. Dare I say that that is
why you need a balun? This asymmetrical shunt impedance is the source
of the whole question.

Not trying to criticize anyone here. I just want to make the
observation that much of the theory that is applied to the systems
discussed here are generalization which only apply under certain
conditions. Often these conditions are "ideal" and even in the best of
circumstances won't match reality perfectly... but are good enough.
Then a discussion starts where something outside the assumptions is
explored and the "ideal" assumptions are forgotten. The discussion goes
in many directions because the general rules are applied when instead,
the topic needs to be considered at a more fundamental level.

So look at the assumptions (or conditions) that exist in this case and
see which ones apply and which don't. I'm pretty sure that the
condition of an impedance match at the feed point does not exist among
others.

That was my point when I suggested that at the junction of the coaxial
feed line and the balun the same condition exists of there being a path
for current on the outside of the shield. This can divert current flow
from the inside of the shield unless... the current path through the
balun from the shield is a very low impedance.

In order to just eliminate any idea of the balun "preventing" an
unbalanced current flow back from the antenna, replace the antenna with
a matched resistor. Then there will be no reflection of any kind at the
load and the only point that needs to be considered is the junction of
the feed line and the balun.

--

Rick

rickman wrote:

On 8/1/2015 9:09 AM, Roger Hayter wrote:
Jeff wrote:

On 01/08/2015 10:54, Roger Hayter wrote:
Jeff wrote:

Conservation of energy also shows that with a perfectly matched
dipole all of the energy applied to it will be radiated, or lost as
heat in the elements. So by extension there can be no power flowing
on the coax outer.

Jeff
So, clearly, the energy supplied from the feeder and conducted down the
coax outer nerver reaches the antenna. Just as two resistors in
parallel share the energy supplied by a voltage applies across them.



No, there will be no energy "supplied from the feeder and conducted down
the coax outer" as it will all be conducted into the antenna and
radiated if the antenna is perfectly balanced. The power flowing up the
coax, when perfectly matched, will only 'see' the antenna load, not the
coax outer as and element in parallel.

Jeff

If it was perfectly balanced before you connected the feeder, it will no
longer be perfectly balanced once the shunt impedance to earth of the
coax braid is connected to *one* side of it. Dare I say that that is
why you need a balun? This asymmetrical shunt impedance is the source
of the whole question.

Not trying to criticize anyone here. I just want to make the
observation that much of the theory that is applied to the systems
discussed here are generalization which only apply under certain
conditions. Often these conditions are "ideal" and even in the best of
circumstances won't match reality perfectly... but are good enough.
Then a discussion starts where something outside the assumptions is
explored and the "ideal" assumptions are forgotten. The discussion goes
in many directions because the general rules are applied when instead,
the topic needs to be considered at a more fundamental level.

So look at the assumptions (or conditions) that exist in this case and
see which ones apply and which don't. I'm pretty sure that the
condition of an impedance match at the feed point does not exist among
others.

That was my point when I suggested that at the junction of the coaxial
feed line and the balun the same condition exists of there being a path
for current on the outside of the shield. This can divert current flow
from the inside of the shield unless... the current path through the
balun from the shield is a very low impedance.

In order to just eliminate any idea of the balun "preventing" an
unbalanced current flow back from the antenna, replace the antenna with
a matched resistor. Then there will be no reflection of any kind at the
load and the only point that needs to be considered is the junction of
the feed line and the balun.

Well I agree with your first point. Not least, the conduction path
along the coax outer is more like a radiating element than a lumped
component, because of its length.

But your second point is unhelpful in some circumstances. For instance,
if the type of balun is the inductive coil of the feeder with or without
ferrites, then there simply *is no* current path down the outside of the
feeder from the junction of the balun and the feeder, Except from the
outer of the cable in the balun coil, and it is this that is decoupled
by the inductance.

Secondly, even if you connect a resistor across the end ot the feeder,
consider that the inner conductor just goes to the resistor, but the
outer conductor sees the resistor and the outer side of the braid in
parallel. So you will get RF (and therefore some radiation) on the
outer of the coax even if you just connect a resistor across the end.
This would actually be quite a simple lab experiment, at UHF or higher.
Compare the amount of RF on the outer with a bare surface mount 50ohm or
with one of the screened 50 ohm terminations (which does not allow any
signal to get to the outer). Or compare the SWR which will be near 1.0
with the screened load and might be very different with the unscreened,
sim,ply because the coax outer is shunting one side of the load.


--
Roger Hayter

Jeff wrote:

No, there will be no energy "supplied from the feeder and conducted down
the coax outer" as it will all be conducted into the antenna and
radiated if the antenna is perfectly balanced. The power flowing up the
coax, when perfectly matched, will only 'see' the antenna load, not the
coax outer as and element in parallel.

Jeff

If it was perfectly balanced before you connected the feeder, it will no
longer be perfectly balanced once the shunt impedance to earth of the
coax braid is connected to *one* side of it. Dare I say that that is
why you need a balun? This asymmetrical shunt impedance is the source
of the whole question.


So if what you are saying is correct then terminating a piece of coax
with a 50 ohm resistor will not cause a perfect match and the load will
not be 50 ohms due to the shunt impedance to earth of the coax braid.

I think not.

Jeff

I agree I was probably wrong, and you are probably correct.

--
Roger Hayter

On 8/2/2015 4:20 AM, Jeff wrote:

No, there will be no energy "supplied from the feeder and conducted down
the coax outer" as it will all be conducted into the antenna and
radiated if the antenna is perfectly balanced. The power flowing up the
coax, when perfectly matched, will only 'see' the antenna load, not the
coax outer as and element in parallel.

Jeff

If it was perfectly balanced before you connected the feeder, it will no
longer be perfectly balanced once the shunt impedance to earth of the
coax braid is connected to *one* side of it. Dare I say that that is
why you need a balun? This asymmetrical shunt impedance is the source
of the whole question.


So if what you are saying is correct then terminating a piece of coax
with a 50 ohm resistor will not cause a perfect match and the load will
not be 50 ohms due to the shunt impedance to earth of the coax braid.

I think not.

Maybe you can draw a diagram and show yourself where the current flows.
The earth connection on the shield outside is in parallel with the
earth connection on the shield inside. You can't have any current flow
on the outside because any current flowing on the shield inside balances
with the current flowing in the center conductor. The resistor requires
the two currents are equal with none left to travel down the shield
outside.

Although I am still waiting for jim to explain his idea that there is no
current flow in the coax. If that is true it will make this a *very*
simple picture.

--

Rick