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Old November 3rd 04, 09:59 AM
Guntier C.
 
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Default wilson 1000 coax legnth

I received and old wilson 1000 mag. mount and want to put it on my quad
(4 magnet) mount. I hear that I need a 18 ft. piece of coax for a
counterpoise. Is that true? Any info appreciated.

Thanks,

G.C.

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Old November 3rd 04, 11:34 AM
sideband
 
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Coax length is unimportant. However much you need to get from the
antenna to your radio is plenty.

If you're matching SWR with coax length, there's something wrong with
your antenna.

-SSB

Guntier C. wrote:

I received and old wilson 1000 mag. mount and want to put it on my quad
(4 magnet) mount. I hear that I need a 18 ft. piece of coax for a
counterpoise. Is that true? Any info appreciated.

Thanks,

G.C.


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Old November 3rd 04, 02:32 PM
Chad Wahls
 
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Default


"Guntier C." wrote in message
...
Thanks Sir, I did not think that was correct. This person said it was
needed because it was mag. mount. Kind of through it was a bunch of bull.

Thanks,

G.C.




That person did not know the difference between RF ground and electrical
ground. A solid electrical connection makes a decent RF ground in vehicles
most of the time but it does not work backwards. Even though the base is
insulated there is still an RF ground.

Fuggedaboudit and enjoy your antenna!!!

Chad


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Old November 3rd 04, 10:57 PM
 
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On Wed, 03 Nov 2004 01:59:15 -0800, "Guntier C."
wrote:

I received and old wilson 1000 mag. mount and want to put it on my quad
(4 magnet) mount. I hear that I need a 18 ft. piece of coax for a
counterpoise. Is that true? Any info appreciated.

Thanks,

G.C.


I'll get slammed for posting the correct answer but what else is new.

Manufacturers of Magnetic mount antennas recommend keeping the
original length of coax.( Wilson, K40, RS, Antenna Specialist, ect.).
Why do they do that? The answer is simple. They realize that there
is no such thing as a perfect or exact scenario for an antenna
installation. They know that in a typical installation of their
antenna the coax length will most likely come into play and can
be beneficial. It can be beneficial in that typically the radio will
see a better load with the manufacturers recommended coax length.

It's not that these antennas can't work with any length of coax. It's
just that in most cases you'll get better results with the recommended
length.



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Old November 4th 04, 05:23 AM
Guntier C.
 
Posts: n/a
Default

Chad Wahls wrote:
"Guntier C." wrote in message
...

Thanks Sir, I did not think that was correct. This person said it was
needed because it was mag. mount. Kind of through it was a bunch of bull.

Thanks,

G.C.





That person did not know the difference between RF ground and electrical
ground. A solid electrical connection makes a decent RF ground in vehicles
most of the time but it does not work backwards. Even though the base is
insulated there is still an RF ground.

Fuggedaboudit and enjoy your antenna!!!

Chad


Yep, sounds about right Chad....

Thanks,

G.C.

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Old November 4th 04, 05:09 PM
Jimmie
 
Posts: n/a
Default


wrote in message
...
On Wed, 03 Nov 2004 01:59:15 -0800, "Guntier C."
wrote:

I received and old wilson 1000 mag. mount and want to put it on my quad
(4 magnet) mount. I hear that I need a 18 ft. piece of coax for a
counterpoise. Is that true? Any info appreciated.

Thanks,

G.C.


I'll get slammed for posting the correct answer but what else is new.

Manufacturers of Magnetic mount antennas recommend keeping the
original length of coax.( Wilson, K40, RS, Antenna Specialist, ect.).
Why do they do that? The answer is simple. They realize that there
is no such thing as a perfect or exact scenario for an antenna
installation. They know that in a typical installation of their
antenna the coax length will most likely come into play and can
be beneficial. It can be beneficial in that typically the radio will
see a better load with the manufacturers recommended coax length.

It's not that these antennas can't work with any length of coax. It's
just that in most cases you'll get better results with the recommended
length.

Agreed with tnon. As soon as someone mentions about using a certain length
of coax with the CB antenna someone always asssumes it is to adjust SWR. It
will not do this. It will change the impedance the radio sees which is not
the same as changing the SWR. For example if the impedance of the antenna is
25 ohms 18ft of coax will make the antenna appear as 100 ohms at the radio.
SWR will be 2:1 reguardless of the length of the cable. AS most radios are
antennas are installed plug and go without benifit of tuning and most all CB
antenas represent an impedance lower than 50 ohms antenna manufactures
typically reccomend the 18ft coax for best results under these conditions.
Most radios work better if they are mismatched above 50 than below 50. This
really becomes noticable if SWR is around 3:1. Not uncommon on a typical
plug and go installation. Otherwise length does not matter much on a well
tuned and properly installed radio and antenna.


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Old November 4th 04, 07:33 PM
sideband
 
Posts: n/a
Default

Jimmie:

SWR is a direct measurement of impedance mismatch. If you change the
coax length, thereby changing the angle the coax is conducting, and
the SWR changes, then there is something wrong with the antenna itself
that needs to be fixed.

Physics dictates this. There's no way around it.

Coax Length DOES NOT MATTER for a single antenna setup. Period.

-SSB

Jimmie wrote:

wrote in message
...

On Wed, 03 Nov 2004 01:59:15 -0800, "Guntier C."
wrote:


I received and old wilson 1000 mag. mount and want to put it on my quad
(4 magnet) mount. I hear that I need a 18 ft. piece of coax for a
counterpoise. Is that true? Any info appreciated.

Thanks,

G.C.


I'll get slammed for posting the correct answer but what else is new.

Manufacturers of Magnetic mount antennas recommend keeping the
original length of coax.( Wilson, K40, RS, Antenna Specialist, ect.).
Why do they do that? The answer is simple. They realize that there
is no such thing as a perfect or exact scenario for an antenna
installation. They know that in a typical installation of their
antenna the coax length will most likely come into play and can
be beneficial. It can be beneficial in that typically the radio will
see a better load with the manufacturers recommended coax length.

It's not that these antennas can't work with any length of coax. It's
just that in most cases you'll get better results with the recommended
length.


Agreed with tnon. As soon as someone mentions about using a certain length
of coax with the CB antenna someone always asssumes it is to adjust SWR. It
will not do this. It will change the impedance the radio sees which is not
the same as changing the SWR. For example if the impedance of the antenna is
25 ohms 18ft of coax will make the antenna appear as 100 ohms at the radio.
SWR will be 2:1 reguardless of the length of the cable. AS most radios are
antennas are installed plug and go without benifit of tuning and most all CB
antenas represent an impedance lower than 50 ohms antenna manufactures
typically reccomend the 18ft coax for best results under these conditions.
Most radios work better if they are mismatched above 50 than below 50. This
really becomes noticable if SWR is around 3:1. Not uncommon on a typical
plug and go installation. Otherwise length does not matter much on a well
tuned and properly installed radio and antenna.



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Old November 4th 04, 09:02 PM
 
Posts: n/a
Default

On Thu, 04 Nov 2004 19:33:08 GMT, sideband wrote:

Jimmie:

SWR is a direct measurement of impedance mismatch. If you change the
coax length, thereby changing the angle the coax is conducting, and
the SWR changes, then there is something wrong with the antenna itself
that needs to be fixed.

Physics dictates this. There's no way around it.

Coax Length DOES NOT MATTER for a single antenna setup. Period.

-SSB


I'd only agree if the antenna perfectly decoupled and was a perfect
load for the radio. In other words if everything operated perfectly
in a perfect world.

As far as mag mounts and using a automobiles as a counterpoise ? ? ?
That scenario is not even close to a perfect world.

I often wonder why there is so much criticism when one suggests
using the manufacturers recommended length. This criticism seems to
be followed by the statement that "any length will do". They believe
that 10 feet, 11 feet, 13.5 feet,ect. ect. are fine. Just don't pick
18 feet !!!!!! How hypocritical is that? Isn't 18' also a length
contained within the statement "any length will do"?


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Old November 4th 04, 09:59 PM
sideband
 
Posts: n/a
Default

tnom:

Explain this, then... CB radio in my Peterbilt, with a mirror mounted
Hustler HQ-27 on the driver's side.. 6 feet of coax shows a 1:1 on 19,
1.1:1 on 1, and 1.1:1 on 40... 12 feet of coax shows the same
readings... 18 feet of coax shows.. guess what? the SAME RESULTS.

IT IS possible to get near "perfect world" results with a little work,
and attention to detail.

By the way, I've gotten similar results on two meters with a magnet
mount 5/8 2M Lakeview whip on my old Ford LTLA9000. Had to shorten the
coax because I was sick of the bundle of it in the cab... no change in
SWR over a four MHz bandwidth...

There goes the "magmount theory" as well..

If changing the length of the coax changes the SWR, then there is
something wrong with the antenna.

-SSB

wrote:

I'd only agree if the antenna perfectly decoupled and was a perfect
load for the radio. In other words if everything operated perfectly
in a perfect world.

As far as mag mounts and using a automobiles as a counterpoise ? ? ?
That scenario is not even close to a perfect world.

I often wonder why there is so much criticism when one suggests
using the manufacturers recommended length. This criticism seems to
be followed by the statement that "any length will do". They believe
that 10 feet, 11 feet, 13.5 feet,ect. ect. are fine. Just don't pick
18 feet !!!!!! How hypocritical is that? Isn't 18' also a length
contained within the statement "any length will do"?



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