Vertical problem
 

Hi. Have a new Hustler 6 band vertical. Installed the radials and also buried 75 foot of RG213 coax between shack and antenna. I used a 6 foot peace of coax connected to adjust the antenna with a MFJ-259. Every band was tuned to the middle and SWR was lower than 1.7:1 at the edges. After the adjustments, I reconnected the buried coax to the antenna and on all bands everything had shift up by any where from 200 to 400 khz. Now the rig is seeing greater than 2:1 SWR.
Should I retune the antenna with the MFJ 259 in the shack?
Thanks Vern M0WQR

Vertical problem
 

826,
My first thought is that the feed line has become 'part' of the
antenna and has changed the antenna's characteristics accordingly. My
second though, if that 6 foot of feed line was connected directly to
the antenna when measurements were taken, is that you being that close
to the antenna changed it's characteristics.
So, what to do? How about doing that checking from the end of the
feed line that will normally be used? Make any antenna adjustments
accordingly. Don't want that feed line to be 'part' of the antenna?
Well, how about using a feed line to do the checking that's of an
appropriate length to sort of 'cancel' it's self out, to do the
checking?
Doing all that checking will also give you some idea as to the
accuracy of your measuring device, and the characteristic values of
the feed lines, etc, sort of.
That's the 'long' version. The 'short' version is that you're
probably doing something wrong, re-do it.
- 'Doc

Not much of an answer, huh?

Vertical problem
 

wrote in message
...


826,
My first thought is that the feed line has become 'part' of the
antenna and has changed the antenna's characteristics accordingly. My
second though, if that 6 foot of feed line was connected directly to
the antenna when measurements were taken, is that you being that close
to the antenna changed it's characteristics.
So, what to do? How about doing that checking from the end of the
feed line that will normally be used? Make any antenna adjustments
accordingly. Don't want that feed line to be 'part' of the antenna?
Well, how about using a feed line to do the checking that's of an
appropriate length to sort of 'cancel' it's self out, to do the
checking?
Doing all that checking will also give you some idea as to the
accuracy of your measuring device, and the characteristic values of
the feed lines, etc, sort of.
That's the 'long' version. The 'short' version is that you're
probably doing something wrong, re-do it.
- 'Doc

Not much of an answer, huh?


Surprise!

It is turning out that coax isn't what you thought it was, is it?

Lots of folks think that coax is some miracle device that absolutely
contains all of the RF until the RF reaches (poetic license please) the
termination point. In truth, no such creature exists in any form of
transmission line.

What you are trying to do is to make the transmission line the worst
possible radiator and the antenna the best possible radiator. There are
gazillions of possibilities somewhere betwen those two potentials.

Run the full length of transmission line into your shack and then tune the
antenna based upon the data gathered in the shack. Yes, it is a PITA, but it
is the only way to do it, if you want the best tuning.

Every antenna system is just that, a system. It cannot be tuned piecemeal to
obtain the best end result. Welcome to the world of radio.

Oh, it isn't so bad once you get used to it. Now you have an excuse to
invite a ham over to help you by reading the analyzer while you are outside
making adjustments to the antenna.

Wait until you discover, if you haven't already, that adjusting one part of
the antenna will cause you to readjust another part of the antenna, probably
the one that you adjusted before the last part that you adjusted. Hang in
there. It is doable. Good luck with your project.

Jack

Vertical problem
 

On Fri, 25 Jul 2008 18:44:46 +0100, "826" wrote:

Hi. Have a new Hustler 6 band vertical. Installed the radials and
also buried 75 foot of RG213 coax between shack and antenna.
I used a 6 foot peace of coax connected to adjust the antenna
with a MFJ-259. Every band was tuned to the middle and SWR
was lower than 1.7:1 at the edges. After the adjustments, I
reconnected the buried coax to the antenna and on all bands
everything had shift up by any where from 200 to 400 khz.
Now the rig is seeing greater than 2:1 SWR.
Should I retune the antenna with the MFJ 259 in the shack?
Thanks Vern M0WQR

I have a 5BTV with buried radials. Works and tunes like crap without
the radials. Tune the antenna with the 259 connected to it with the
shortest piece of coax you can work with, like 1 foot. If you're a
purist - which I advise - lie down so you're as much out of the
antenna field as possible when taking readings. Or back way off and
read with binoculars. (Just don't let your body affect the antenna
tuning.) When that's done, coil the main coax or use a common mode
choke where the coax connects to the antenna to prevent the coax
shield from acting like a radial. Forget that nonsense of adjusting
SWR by adjusting coax length unless you're prepared to use a different
length for every band.

The MFJ 259 reads SWR with respect to it's own 50-ohm nominal
impedance so if you can adjust to a very low SWR (and you can with a
5BTV or 6BTV), it should read the same at the radio end of a longer
50-ohm coax.

Vertical problem
 

Hi, Thanks for all your input. Hustler recommended using 5-6 foot of coax in
there manual. This I did follow and the antenna tuned very nice. When I
connected the 75 ft buried coax it threw me because the resonance frequency
on each band went higher. I do not have a balun at the base of the antenna.
I thought that after connecting the buried coax the frequency would go down
because of the capacitance of the longer coax. After rethinking this I can
see that adding a balun may help. Thanks for your help and will let you know
how things turn out.
Vern M0WQR

"Jim Higgins" wrote in message
...
On Fri, 25 Jul 2008 18:44:46 +0100, "826" wrote:

Hi. Have a new Hustler 6 band vertical. Installed the radials and
also buried 75 foot of RG213 coax between shack and antenna.
I used a 6 foot peace of coax connected to adjust the antenna
with a MFJ-259. Every band was tuned to the middle and SWR
was lower than 1.7:1 at the edges. After the adjustments, I
reconnected the buried coax to the antenna and on all bands
everything had shift up by any where from 200 to 400 khz.
Now the rig is seeing greater than 2:1 SWR.
Should I retune the antenna with the MFJ 259 in the shack?
Thanks Vern M0WQR

I have a 5BTV with buried radials. Works and tunes like crap without
the radials. Tune the antenna with the 259 connected to it with the
shortest piece of coax you can work with, like 1 foot. If you're a
purist - which I advise - lie down so you're as much out of the
antenna field as possible when taking readings. Or back way off and
read with binoculars. (Just don't let your body affect the antenna
tuning.) When that's done, coil the main coax or use a common mode
choke where the coax connects to the antenna to prevent the coax
shield from acting like a radial. Forget that nonsense of adjusting
SWR by adjusting coax length unless you're prepared to use a different
length for every band.

The MFJ 259 reads SWR with respect to it's own 50-ohm nominal
impedance so if you can adjust to a very low SWR (and you can with a
5BTV or 6BTV), it should read the same at the radio end of a longer
50-ohm coax.

Vertical problem
 

Funny, I've seen no one recommend addition of a 1:1 choke balun near the
antenna feedpoint. If RF is flowing back down the shield of his feedline,
that surely could cause some incorrect readings on SWR in the shack,
wouldn't it?

Ed K7AAT

Vertical problem
 

On 27 Jul 2008 23:26:04 GMT, Ed wrote:


Funny, I've seen no one recommend addition of a 1:1 choke balun near the
antenna feedpoint. If RF is flowing back down the shield of his feedline,
that surely could cause some incorrect readings on SWR in the shack,
wouldn't it?

And, how well would rf flow back down the shield of
"buried 75 foot of RG213..." ? :-)

Jonesy
--
Marvin L Jones | jonz | W3DHJ | linux
38.24N 104.55W | @ config.com | Jonesy | OS/2
*** Killfiling google posts: http://jonz.net/ng.htm

Vertical problem
 

Funny, I've seen no one recommend addition of a 1:1 choke balun
near the
antenna feedpoint. If RF is flowing back down the shield of his
feedline, that surely could cause some incorrect readings on SWR in
the shack, wouldn't it?

And, how well would rf flow back down the shield of
"buried 75 foot of RG213..." ? :-)



About as well as it flows up the center conductor, possibly. You
don't think that just because the cable is buried that RF flow on the
shield conductor is prevented, do you?

Ed

Vertical problem
 

Ed wrote:

...
About as well as it flows up the center conductor, possibly. You
don't think that just because the cable is buried that RF flow on the
shield conductor is prevented, do you?

Ed

I sure can imagine one heck of a "capacitive load" on that outer
conductor to ground! What, thousands/tens-of-thousands of pf?

Regards,
JS

Vertical problem
 

On 28 Jul 2008 04:03:29 GMT, Ed
wrote:

About as well as it flows up the center conductor, possibly. You
don't think that just because the cable is buried that RF flow on the
shield conductor is prevented, do you?

Hi Ed,

I think Jonesy is fairly safe in his presumption. The classic work
performed by Brown, Lewis, and Epstein pretty conclusively reported
the nearly complete attenuation of direct driven RF currents in ground
radials at 3MHz.

75 feet of buried shield would seem to be quite snubbed by the
proximity of earth over much of the range of frequencies reliably
operated from a multi-band HF vertical.

Of course, adding a choke can't hurt.

73's
Richard Clark, KB7QHC

Vertical problem
 

Richard Clark wrote:
On 28 Jul 2008 04:03:29 GMT, Ed
wrote:

About as well as it flows up the center conductor, possibly. You
don't think that just because the cable is buried that RF flow on the
shield conductor is prevented, do you?

Hi Ed,

I think Jonesy is fairly safe in his presumption. The classic work
performed by Brown, Lewis, and Epstein pretty conclusively reported
the nearly complete attenuation of direct driven RF currents in ground
radials at 3MHz.

75 feet of buried shield would seem to be quite snubbed by the
proximity of earth over much of the range of frequencies reliably
operated from a multi-band HF vertical.

Of course, adding a choke can't hurt.

73's
Richard Clark, KB7QHC

What Richard neglected to specify is that the work of B, L, & E shows
that there won't be significant current on the *outside* of the shield
because of the burial. The current on the *inside* won't be affected.

What's unknown is whether there was significant current on the outside
during the measurement with the shorter cable. If so, the cable and
probably the person doing the measuring became part of the antenna and
would therefore affect its impedance.

Roy Lewallen, W7EL

Vertical problem
 

On Sun, 27 Jul 2008 21:49:05 +0100, "826" wrote:

Hi, Thanks for all your input. Hustler recommended using 5-6 foot of coax in
there manual. This I did follow and the antenna tuned very nice.

I more than just suspect the length recommendation has a lot to do
with the effect of your body closer to the antenna and nothing to do
with the varying length of the coax as a matching network.

When I
connected the 75 ft buried coax it threw me because the resonance frequency
on each band went higher. I do not have a balun at the base of the antenna.
I thought that after connecting the buried coax the frequency would go down
because of the capacitance of the longer coax. After rethinking this I can
see that adding a balun may help. Thanks for your help and will let you know
how things turn out.
Vern M0WQR

You're welcome. Yes, I would be interested in hearing how it turns
out for you. Works well for me.

BTW, my coax lays on top of the ground. Shouldn't matter with the
choke at the feed point.

73, Jim KB3PU


"Jim Higgins" wrote in message
.. .
On Fri, 25 Jul 2008 18:44:46 +0100, "826" wrote:

Hi. Have a new Hustler 6 band vertical. Installed the radials and
also buried 75 foot of RG213 coax between shack and antenna.
I used a 6 foot peace of coax connected to adjust the antenna
with a MFJ-259. Every band was tuned to the middle and SWR
was lower than 1.7:1 at the edges. After the adjustments, I
reconnected the buried coax to the antenna and on all bands
everything had shift up by any where from 200 to 400 khz.
Now the rig is seeing greater than 2:1 SWR.
Should I retune the antenna with the MFJ 259 in the shack?
Thanks Vern M0WQR

I have a 5BTV with buried radials. Works and tunes like crap without
the radials. Tune the antenna with the 259 connected to it with the
shortest piece of coax you can work with, like 1 foot. If you're a
purist - which I advise - lie down so you're as much out of the
antenna field as possible when taking readings. Or back way off and
read with binoculars. (Just don't let your body affect the antenna
tuning.) When that's done, coil the main coax or use a common mode
choke where the coax connects to the antenna to prevent the coax
shield from acting like a radial. Forget that nonsense of adjusting
SWR by adjusting coax length unless you're prepared to use a different
length for every band.

The MFJ 259 reads SWR with respect to it's own 50-ohm nominal
impedance so if you can adjust to a very low SWR (and you can with a
5BTV or 6BTV), it should read the same at the radio end of a longer
50-ohm coax.

Vertical problem
 

...
About as well as it flows up the center conductor, possibly. You
don't think that just because the cable is buried that RF flow on the
shield conductor is prevented, do you?

Ed

I sure can imagine one heck of a "capacitive load" on that outer
conductor to ground! What, thousands/tens-of-thousands of pf?

Regards,
JS


I was not aware of the depth, length, and other specifics of the
buried coax installation as I jumped into the thread a bit late. Sorry.
Here where I'm located we have nothing but sand, which doesn't really
provide much of a ground. I forget other people have real dirt! :^)

Ed

Vertical problem
 

Hi,
Here is some more info. The depth of the coax is 6". Its length is 75 foot
of RG-213. The ground here is below sea level (3 ft). It was reclaimed from
salt water by wind driven pumps in the 14th and 15th century. The
conductivity of the ground is great for antennas. But not sure about buried
feed lines.
I tested the antenna with the MFP-259 and 6 ft of cable on the ground. Yes
the first thing I checked was if the reading changed if I backed off from
the instrument and antenna.
I have tried buried coax one other time with a 2m vertical and thought the
coax was bad because it was used before. It also gave bad reading but can
remember the details. Do remember running another peace of coax back to the
shack overhead and everything was OK.
Now I wondering if it is something to do with the installation. The coax is
new and inside of a garden hose for protection. I did check the hose to make
sure it was dry before it was used.
I know that the antenna is adjusted correctly and have taken an FT-817 and
SWR meter to the antenna and it also indicated good readings.
Now something tells me not to tune the antenna with the instruments locate
in the shack because it will not be curing the problem. It will just hid it
until I start running some power. Then I would think something would start
to get hot in the field. Like the traps.
Because the antenna no longer wants my power because its no longer tuned to
the ham bands.
Regards
Vern

"Ed" wrote in message
92.196...
...
About as well as it flows up the center conductor, possibly. You
don't think that just because the cable is buried that RF flow on the
shield conductor is prevented, do you?

Ed

I sure can imagine one heck of a "capacitive load" on that outer
conductor to ground! What, thousands/tens-of-thousands of pf?

Regards,
JS


I was not aware of the depth, length, and other specifics of the
buried coax installation as I jumped into the thread a bit late. Sorry.
Here where I'm located we have nothing but sand, which doesn't really
provide much of a ground. I forget other people have real dirt! :^)

Ed

Vertical problem
 

826 wrote:
Hi,
Here is some more info. The depth of the coax is 6". Its length is 75 foot
of RG-213. The ground here is below sea level (3 ft). It was reclaimed from
salt water by wind driven pumps in the 14th and 15th century. The
conductivity of the ground is great for antennas. But not sure about buried
feed lines.
...

I, like Richard C., would like to encourage you to the use of a 1:1
current-choke/balun, either of a toroid core of proper material--or even
a ferrite rod, beads, etc. -- and installed at the antenna feed point or
both ends of the coax (xmitter also) ...

I would have to install software and check out a couple of things. But,
I suspect, and especially at ~28+ mhz, that capacitive load on the outer
conductor can't help look like anything other than/near a direct short.
Even the rf down the inside of the braid/shield must be tempted to
that path if it nears or is less than ~50 ohms (well, some
possible/noticeable effect/affect.)

The coax I have buried, I always encased in ~1 inch PVC--possibly an
overkill ... but hey, it was cheap when I bought it--I ran the UNUN
(unbalanced-to-unbalanced current balun), just don't remember if I had
to, or not ...

Just my two cents worth--feel free to disregard if someone ventures
better/more-accurate data or proofs ... but then, you already knew that.
;-)

Regards,
JS

Vertical problem
 

One other thing comes to mind: When you measured the antenna through the
short piece of coax, was the shield of the long buried piece connected
to the antenna's ground system? If not, you might try that. It would act
as an additional radial, which would have some affect on the antenna's
impedance.

Roy Lewallen, W7EL

Vertical problem
 

On Mon, 28 Jul 2008 19:55:16 +0100, "826" wrote:

Now something tells me not to tune the antenna with the instruments locate
in the shack because it will not be curing the problem. It will just hid it
until I start running some power. Then I would think something would start
to get hot in the field. Like the traps.

Hi Vern,

You DO want to tune the antenna with instruments located in the shack.
You are tuning an "antenna system" and the complete system should
appear to be resonate to both the instruments AND the transmitter.
More power (or less power) should have nothing to do with the state of
tune - unless you have an intermittent. If you have an intermittant,
this is a failure, not a mis-adjustment.

From other indications you have shared, your problem is a
comparatively subtle error, not a major failure.

73's
Richard Clark, KB7QHC

Vertical problem
 

"826" wrote in
:

Hi. Have a new Hustler 6 band vertical. Installed the radials and also
buried 75 foot of RG213 coax between shack and antenna. I used a 6
foot peace of coax connected to adjust the antenna with a MFJ-259.
Every band was tuned to the middle and SWR was lower than 1.7:1 at the
edges. After the adjustments, I reconnected the buried coax to the
antenna and on all bands everything had shift up by any where from 200
to 400 khz. Now the rig is seeing greater than 2:1 SWR.
Should I retune the antenna with the MFJ 259 in the shack?

Vern,

An oft asked question, and there are usually emphatic answers readily
proffered.

You might find my article at http://www.vk1od.net/VSWR/displacement.htm
relevant to understanding what goes on 'within' the transmission line,
and the 'Traps for players' heading offers reasons why behaviour that is
inconsistent with transmission line behaviour may be observed.

In your case, one of the things you appear to have done is the change the
thing that was measured. You adjusted the antenna with the shield of the
main feedline disconnected. This is discussed under the heading
'Disturbing the thing being measured'.

Owen

Vertical problem
 

Owen Duffy wrote:
"826" wrote in
:

Hi. Have a new Hustler 6 band vertical. Installed the radials and also
buried 75 foot of RG213 coax between shack and antenna. I used a 6
foot peace of coax connected to adjust the antenna with a MFJ-259.
Every band was tuned to the middle and SWR was lower than 1.7:1 at the
edges. After the adjustments, I reconnected the buried coax to the
antenna and on all bands everything had shift up by any where from 200
to 400 khz. Now the rig is seeing greater than 2:1 SWR.
Should I retune the antenna with the MFJ 259 in the shack?

Vern,

An oft asked question, and there are usually emphatic answers readily
proffered.

You might find my article at http://www.vk1od.net/VSWR/displacement.htm
relevant to understanding what goes on 'within' the transmission line,
and the 'Traps for players' heading offers reasons why behaviour that is
inconsistent with transmission line behaviour may be observed.

In your case, one of the things you appear to have done is the change the
thing that was measured. You adjusted the antenna with the shield of the
main feedline disconnected. This is discussed under the heading
'Disturbing the thing being measured'.

Owen

But, if the choke/balun/unun suggested is implemented, shouldn't one
expect the transmission lines influence to measurements be expected to
drop to near zero effect/affect?--i.e., re-routing/lengthening/etc. that
xmission line (coax), opposed to measurements taken?

Or, in effect, your measurement(s) with a 1 ft. length of xmission line
will remain very stable if that length were lengthened to one-hundred
feet?; Given that the choke/balun is of proper construction to offer
HIGH impedance to the freq(s) in question on the outer braid/shield?

I certain have grown to expect this ... have I just been lucky?

Regards,
JS

Vertical problem
 

"Owen Duffy" wrote in message
...
"826" wrote in
:

Hi. Have a new Hustler 6 band vertical. Installed the radials and also
buried 75 foot of RG213 coax between shack and antenna. I used a 6
foot peace of coax connected to adjust the antenna with a MFJ-259.
Every band was tuned to the middle and SWR was lower than 1.7:1 at the
edges. After the adjustments, I reconnected the buried coax to the
antenna and on all bands everything had shift up by any where from 200
to 400 khz. Now the rig is seeing greater than 2:1 SWR.
Should I retune the antenna with the MFJ 259 in the shack?

Vern,

An oft asked question, and there are usually emphatic answers readily
proffered.

You might find my article at http://www.vk1od.net/VSWR/displacement.htm
relevant to understanding what goes on 'within' the transmission line,
and the 'Traps for players' heading offers reasons why behaviour that is
inconsistent with transmission line behaviour may be observed.

In your case, one of the things you appear to have done is the change the
thing that was measured. You adjusted the antenna with the shield of the
main feedline disconnected. This is discussed under the heading
'Disturbing the thing being measured'.

Owen

Hi,
Sorry I didn't rely sooner. The weather hasn't been too good hear. This
morning I disconnected the coax from the shack and measured the antenna with
the six foot length of coax. It looked OK. I then connected just the shield
of the long coax going to the shack and still measuring with the short coax
it shifted just like measured before in the shack. I have then made up a
choke balun and installed it at the base of the antenna and it improved
everything by about 60%. I will now make another one for the shack end. I
think everything is under control now. Thanks to all for heading me in the
right direction.
Vern M0WQR

Vertical problem
 

"826" wrote in
:

Hi,
Sorry I didn't rely sooner. The weather hasn't been too good hear.
This
morning I disconnected the coax from the shack and measured the
antenna with the six foot length of coax. It looked OK. I then
connected just the shield of the long coax going to the shack and
still measuring with the short coax it shifted just like measured
before in the shack. I have then made up a choke balun and installed
it at the base of the antenna and it improved everything by about 60%.
I will now make another one for the shack end. I think everything is
under control now. Thanks to all for heading me in the right
direction. Vern M0WQR

Vern, whilst the choke made a difference, the fact that there remains a
difference in the feedpoint impedance with the shield connected and
disconnected, even when using the choke, indicates that there is some
effects observable from common mode feed line current in your scenario.

If you want a measurement of the antenna as it would be used, measure it
as it would be used... make sure the shield current path is as it would
be used.

Owen

Vertical problem
 

On Sun, 27 Jul 2008 21:07:25 -0700, John Smith
wrote:

Ed wrote:

...
About as well as it flows up the center conductor, possibly. You
don't think that just because the cable is buried that RF flow on the
shield conductor is prevented, do you?

Ed

I sure can imagine one heck of a "capacitive load" on that outer
conductor to ground! What, thousands/tens-of-thousands of pf?

Regards,
JS

95% plus of the transmitter or received energy is safely contained
between center conductor and shield. That is how the physics works
out. All of the feed line center conductor current is pretty well
matched by the same current in the shield. It is the closely coupled
concentric magnetic fields that make coax work so well.

Vertical problem
 

JosephKK wrote:

...
95% plus of the transmitter or received energy is safely contained
between center conductor and shield. That is how the physics works
out. All of the feed line center conductor current is pretty well
matched by the same current in the shield. It is the closely coupled
concentric magnetic fields that make coax work so well.


Or, simply put, for ever action, an equal and opposite reaction occurs
.... yes, basic physics ... however, what is in question--since the other
braid has and "inside" and an "outside", where does that equal opposite
reaction occur ...

Regard,
JS

Vertical problem
 

John Smith wrote:
JosephKK wrote:

...
95% plus of the transmitter or received energy is safely contained
between center conductor and shield. That is how the physics works
out. All of the feed line center conductor current is pretty well
matched by the same current in the shield. It is the closely coupled
concentric magnetic fields that make coax work so well.


Or, simply put, for ever action, an equal and opposite reaction occurs
... yes, basic physics ... however, what is in question--since the other
braid has and "inside" and an "outside", where does that equal opposite
reaction occur ...

Regard,
JS


Gawd, I am getting hasty in my old age ...

No electrical field can occur without a magnet field, no magnetic field
can occur with out a corresponding electrical component, again, basic
physics; you are attempting to say the magnetic component of the
current on the outside of the braid is NOT SEEN by the center conductor
.... that may be in error ... but, I would be willing to listen how
tinned copper (the braid) is some sort of shield to magnetic fields ...

Regards,
JS

Vertical problem
 

John Smith wrote:
John Smith wrote:
JosephKK wrote:

...
95% plus of the transmitter or received energy is safely contained
between center conductor and shield. That is how the physics works
out. All of the feed line center conductor current is pretty well
matched by the same current in the shield. It is the closely coupled
concentric magnetic fields that make coax work so well.


Or, simply put, for ever action, an equal and opposite reaction occurs
... yes, basic physics ... however, what is in question--since the
other braid has and "inside" and an "outside", where does that equal
opposite reaction occur ...

Regard,
JS


Gawd, I am getting hasty in my old age ...

No electrical field can occur without a magnet field, no magnetic field
can occur with out a corresponding electrical component, again, basic
physics; you are attempting to say the magnetic component of the
current on the outside of the braid is NOT SEEN by the center conductor
... that may be in error ... but, I would be willing to listen how
tinned copper (the braid) is some sort of shield to magnetic fields ...

Regards,
JS

Geesh, too old, I am telling you ...

Disregard "static fields", however, that is NOT what is in question here ...

Regards,
JS

Vertical problem
 

JosephKK wrote:

95% plus of the transmitter or received energy is safely contained
between center conductor and shield. That is how the physics works
out. All of the feed line center conductor current is pretty well
matched by the same current in the shield. It is the closely coupled
concentric magnetic fields that make coax work so well.


It's unfortunate that this isn't true. If it were, it would make our
lives a lot easier. Anyone interested in learning more about this topic
might take a look at http://eznec.com/Amateur/Articles/Baluns.pdf.

Roy Lewallen, W7EL

Vertical problem
 

"John Smith" wrote in message
...
John Smith wrote:
John Smith wrote:
JosephKK wrote:

...
95% plus of the transmitter or received energy is safely contained
between center conductor and shield. That is how the physics works
out. All of the feed line center conductor current is pretty well
matched by the same current in the shield. It is the closely coupled
concentric magnetic fields that make coax work so well.


Or, simply put, for ever action, an equal and opposite reaction occurs
... yes, basic physics ... however, what is in question--since the other
braid has and "inside" and an "outside", where does that equal opposite
reaction occur ...

Regard,
JS


Gawd, I am getting hasty in my old age ...

No electrical field can occur without a magnet field, no magnetic field
can occur with out a corresponding electrical component, again, basic
physics; you are attempting to say the magnetic component of the current
on the outside of the braid is NOT SEEN by the center conductor ... that
may be in error ... but, I would be willing to listen how tinned copper
(the braid) is some sort of shield to magnetic fields ...

Regards,
JS

Geesh, too old, I am telling you ...

Disregard "static fields", however, that is NOT what is in question here
...

Regards,
JS

---------

Rats! You beat me to it!

Ed, NM2K

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Ed Cregger wrote:

...
Rats! You beat me to it!

Ed, NM2K



It's about time! Some of these guys have held my feet to the fire!

:-)

Regards,
JS

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Basic physics is fine, but it's possible to reach all sorts of invalid
conclusions if misapplied.

Roy Lewallen, W7EL

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Roy Lewallen wrote:
Basic physics is fine, but it's possible to reach all sorts of invalid
conclusions if misapplied.

Roy Lewallen, W7EL

I have been thinking about this "comment."

And, absolutely!; Things only get more interesting when we can "bend"
the laws ... ;-)

Regards,
JS

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John Smith wrote:
Roy Lewallen wrote:
Basic physics is fine, but it's possible to reach all sorts of invalid
conclusions if misapplied.

Roy Lewallen, W7EL

I have been thinking about this "comment."

And, absolutely!; Things only get more interesting when we can "bend"
the laws ... ;-)

Regards,
JS

Again, gettin' old ...

Fortunate to have Roy, Cecil and others here ... I, certainly, would get
bored without them ... someone I can have a "difference" with ... but
then agree with.

Life is not just good, it is EXCELLENT ... ! and, when they are right,
they are RIGHT!

Regards,
JS

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John Smith wrote:
Things only get more interesting when we can "bend"
the laws ... ;-)

"Whattaya mean 'we', White Man?" Every miracle performed
in "The Bible" can be performed by man today probably
including keeping a man technically dead for three
days and then reviving him (any volunteers?).

I suspect every technical "law" known to man will be broken
in the next 1000 years, if not in the next 100 years. We
have already eaten of the Tree of Knowledge. It will only
be a matter of time until we eat of the Tree of (Eternal)
Life, relatively speaking.
--
73, Cecil http://www.w5dxp.com

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Cecil Moore wrote:
John Smith wrote:
Things only get more interesting when we can "bend" the laws ... ;-)

"Whattaya mean 'we', White Man?" Every miracle performed
in "The Bible" can be performed by man today probably
including keeping a man technically dead for three
days and then reviving him (any volunteers?).


Well, I don't think we can cover the entire earth with water past the
height of the tallest mountains. Like that ever happened tho'.

I suspect every technical "law" known to man will be broken
in the next 1000 years, if not in the next 100 years. We
have already eaten of the Tree of Knowledge. It will only
be a matter of time until we eat of the Tree of (Eternal)
Life, relatively speaking.


I agree, if we manage to survive that long. Which I do not find all that
likely. Or at least if we do, our innate instincts will ensure that we
are at nowhere near the technical level we are today. More likely our
tendency to overpopulate, not plan ahead, and kill anyone who doesn't
look or think as we do will probably leave the survivors to emulate a
lifestyle more akin to the middle ages. There are even some nutters
among us who don't have a problem with that.

- 73 de Mike N3LI -

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Cecil Moore wrote:

...
"Whattaya mean 'we', White Man?" Every miracle performed
in "The Bible" can be performed by man today probably
including keeping a man technically dead for three
days and then reviving him (any volunteers?).

I suspect every technical "law" known to man will be broken
in the next 1000 years, if not in the next 100 years. We
have already eaten of the Tree of Knowledge. It will only
be a matter of time until we eat of the Tree of (Eternal)
Life, relatively speaking.

Interesting "take" on things ... and again, more correct than in error.
:-)

I am thinking about sending ya' the wifes pie plates ... grin

Regards,
JS

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Michael Coslo wrote:
Well, I don't think we can cover the entire earth with water past
the height of the tallest mountains. Like that ever happened tho'.

The original languages, like our own version of English,
had numerous definitions of "earth". I can cover the
"entire earth" in my handful of earth with a pint of water.

At the time of that original tale, man had absolutely no
concept of a 8000 mile diameter "planet earth". "Earth"
was as far (and as flat) as one could see and I have seen
Texas floods, in my lifetime, where nothing but water
could be seen. :-) Heck, I have been sailing on Clear
Lake, out by NASA, when I couldn't see anything but
water in all directions.
--
73, Cecil http://www.w5dxp.com

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John Smith wrote:
Cecil Moore wrote:
...

Cecil:

There are few times in life when a "mind", such as you/yours CAN display
an/multiple "interesting path(s)", as you do, to the likes of myself
-- it comes to "the attention", so frequently, and so rightly so. I
"feel good" about this ...

I only wish there were more of you ... hang it their man, God loves you!
(for krists' sake, I notice!)

With the most warmest regards,
JS

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"Owen Duffy" wrote in message
...
"826" wrote in
:

Hi,
Sorry I didn't rely sooner. The weather hasn't been too good hear.
This
morning I disconnected the coax from the shack and measured the
antenna with the six foot length of coax. It looked OK. I then
connected just the shield of the long coax going to the shack and
still measuring with the short coax it shifted just like measured
before in the shack. I have then made up a choke balun and installed
it at the base of the antenna and it improved everything by about 60%.
I will now make another one for the shack end. I think everything is
under control now. Thanks to all for heading me in the right
direction. Vern M0WQR

Vern, whilst the choke made a difference, the fact that there remains a
difference in the feedpoint impedance with the shield connected and
disconnected, even when using the choke, indicates that there is some
effects observable from common mode feed line current in your scenario.

If you want a measurement of the antenna as it would be used, measure it
as it would be used... make sure the shield current path is as it would
be used.

Owen
Hi all,
The antenna is now working very well on all bands. After installing both
choke baluns at the antenna base and in the shack, the resonant points
measured from the shack end were the same as with the short coax at the
antenna without the longer coax shield connected. Everything is OK now. All
it needed was the two baluns.
Regards
Vern M0WQR

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In article , Cecil Moore
wrote:

John Smith wrote:
Things only get more interesting when we can "bend"
the laws ... ;-)

"Whattaya mean 'we', White Man?" Every miracle performed
in "The Bible" can be performed by man today probably
including keeping a man technically dead for three
days and then reviving him (any volunteers?).


Hello, Cecil, and not quite. I don't know what you mean by "keeping a man
technically dead" but I've haven't seen any reports on 5000 people being
fed with a couple of fish, two people who were quite dead brought back to
life or a person who was blind from birth given the capability of sight.
Or the silly notion that a human being could be killed and, with
assistance from a "higher authority", return to earth in physical form.
Of course a lot of folks find the very idea that these events could have
happened, let alone a couple of millenia ago, is a bunch of crap. Still
one must concede in spite of one's spiritual beliefs that given a
sufficient level of technology, one can indeed perform miraculous feats.
Perhaps we will be able to do (some of) these things some day, but not
today. Sincerely, 73s, and with apologies for injecting OT philosophy,

John Wood (Code 5550) e-mail:
Naval Research Laboratory
4555 Overlook Avenue, SW
Washington, DC 20375-5337

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J. B. Wood wrote:

...
Or the silly notion that a human being could be killed and, with
assistance from a "higher authority", return to earth in physical form.
...

John Wood (Code 5550) e-mail:
Naval Research Laboratory
4555 Overlook Avenue, SW
Washington, DC 20375-5337

I don't know about all that, I would look closer ... they are implanting
stem cells in the retina and restoring sight and all that now ... I
would at least do a complete search of the web first ...

However, you are quite correct "some people" do have some strange,
quaint and bizarre beliefs ... for example: the belief I can take a
handful of wood, glass, metal and plastic, toss 'em into a mud puddle
and come back a couple of million years later and start digging up
microwaves, cell phones, televisions, etc. (it is called, "evolution!")

Yep, you just can never tell what some people can be caused to believe!

Regards,
JS

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826 wrote:

...
Owen
Hi all,
The antenna is now working very well on all bands. After installing both
choke baluns at the antenna base and in the shack, the resonant points
measured from the shack end were the same as with the short coax at the
antenna without the longer coax shield connected. Everything is OK now. All
it needed was the two baluns.
Regards
Vern M0WQR



Your path sounds very similar to mine. At first, unless the plans/specs
called for a balun/choke, I ignored the need. Now I use one, or more,
no matter what ... I picked up that knowledge here. At first, the loss
of the balun/choke made me hesitant--I no longer worry about those
trivial matters. :-)

Regards,
JS