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Old February 23rd 04, 04:16 PM
Scott Downey
 
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Default Is it a CB or VHF marine antenna?

I have a white fiberglass top loaded antenna that is 48 inches long.

At the bottom of the antenna where the metal part screws onto the L bracket
aluminum mounting base is imprinted 'wondershaft'.

It is toploaded because the top 15 inches is thicker and I assume there is a
coil of wire under the white fiberglass covering.
It uses a Pl259 coax connector mount on the base for the coax cable.

Does anyone know if this is a marine CB antenna or would it be a marine VHF
antenna or how to tell the difference?
Thanks for any info.



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Old February 23rd 04, 05:03 PM
David G. Nagel
 
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Scott;

What you have there is a CB antenna. You can tell from the loading coil
at the top of the stick. A VHF marine antenna will not have any coils as
the 48" length is sufficent for a half wave vertical dipole.

Dave WD9BDZ

Scott Downey wrote:
I have a white fiberglass top loaded antenna that is 48 inches long.

At the bottom of the antenna where the metal part screws onto the L bracket
aluminum mounting base is imprinted 'wondershaft'.

It is toploaded because the top 15 inches is thicker and I assume there is a
coil of wire under the white fiberglass covering.
It uses a Pl259 coax connector mount on the base for the coax cable.

Does anyone know if this is a marine CB antenna or would it be a marine VHF
antenna or how to tell the difference?
Thanks for any info.




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Old February 23rd 04, 05:14 PM
Scott Downey
 
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Thank you.
I was hoping toward CB. I am going to add a CB radio to my boat. I already
have a VHF radio.

I have a SWR meter. Will the length of the coax have an effect on the
tuning? I would like to have a run from the top of the flybridge to cabin of
perhaps around 20 feet.

"David G. Nagel" wrote in message
...
Scott;

What you have there is a CB antenna. You can tell from the loading coil
at the top of the stick. A VHF marine antenna will not have any coils as
the 48" length is sufficent for a half wave vertical dipole.

Dave WD9BDZ

Scott Downey wrote:
I have a white fiberglass top loaded antenna that is 48 inches long.

At the bottom of the antenna where the metal part screws onto the L

bracket
aluminum mounting base is imprinted 'wondershaft'.

It is toploaded because the top 15 inches is thicker and I assume there

is a
coil of wire under the white fiberglass covering.
It uses a Pl259 coax connector mount on the base for the coax cable.

Does anyone know if this is a marine CB antenna or would it be a marine

VHF
antenna or how to tell the difference?
Thanks for any info.






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Old February 23rd 04, 05:27 PM
Cecil Moore
 
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Scott Downey wrote:
I have a SWR meter. Will the length of the coax have an effect on the
tuning? I would like to have a run from the top of the flybridge to cabin of
perhaps around 20 feet.


Is the (metal?) flybridge your ground plane?
--
73, Cecil http://www.qsl.net/w5dxp



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Old February 23rd 04, 06:29 PM
Scott Downey
 
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The boat is mostly wood and fiberglass, only metal is railings.


"Cecil Moore" wrote in message
...
Scott Downey wrote:
I have a SWR meter. Will the length of the coax have an effect on the
tuning? I would like to have a run from the top of the flybridge to

cabin of
perhaps around 20 feet.


Is the (metal?) flybridge your ground plane?
--
73, Cecil http://www.qsl.net/w5dxp



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Old February 23rd 04, 06:35 PM
Scott Downey
 
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There is a large stainless metal ground plate with molded in tubes (
increased surface area) attached to the keel.
About 4 feet by 2 feet. I was told years ago these plates may have been used
for AM ground plates??? when using an AM transmitter or perhaps for
lightening protection. The boat was built in 1970. All the electronics are
grounded and this is also included in the ground.

"Cecil Moore" wrote in message
...
Scott Downey wrote:
I have a SWR meter. Will the length of the coax have an effect on the
tuning? I would like to have a run from the top of the flybridge to

cabin of
perhaps around 20 feet.


Is the (metal?) flybridge your ground plane?
--
73, Cecil http://www.qsl.net/w5dxp



-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
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-----== Over 100,000 Newsgroups - 19 Different Servers! =-----



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Old February 23rd 04, 07:08 PM
Cecil Moore
 
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Default

Scott Downey wrote:
The boat is mostly wood and fiberglass, only metal is railings.


To what is the coax shield going to be tied? If that antenna is
an electrical 1/4 wavelength, where's the ground plane?
--
73, Cecil http://www.qsl.net/w5dxp



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Old February 23rd 04, 08:17 PM
WB2JKX
 
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Default


Scott Downey wrote in message
...
There is a large stainless metal ground plate with molded in tubes (
increased surface area) attached to the keel.
About 4 feet by 2 feet. I was told years ago these plates may have been

used
for AM ground plates??? when using an AM transmitter or perhaps for
lightening protection. The boat was built in 1970. All the electronics

are
grounded and this is also included in the ground.


Probably would work O.K. for the 2-3 Mhz HF marine band and a mast supported
antenna wire, but you'll need a "local" groundplane for the 27Mhz antenna to
attach the coax shield to, as was previously questioned.




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Old February 23rd 04, 09:35 PM
Scott Downey
 
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Default

Are you saying it wont work?
Why would the manufacturer make a marine CB antenna knowing it would be put
on a fiberglass boat knowing that most people would simply hook up the coax
and see it it works.
I read in the marine catalogs about marine CB antennas designed for boats
and not to be concerned about a ground plane.
Anyone know the answer?


"Cecil Moore" wrote in message
...
Scott Downey wrote:
The boat is mostly wood and fiberglass, only metal is railings.


To what is the coax shield going to be tied? If that antenna is
an electrical 1/4 wavelength, where's the ground plane?
--
73, Cecil http://www.qsl.net/w5dxp



-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
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-----== Over 100,000 Newsgroups - 19 Different Servers! =-----



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Old February 23rd 04, 09:54 PM
Scott Downey
 
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Default

I found this

"I agree with the other posts. The length of cable is not an issue and your
problem is a lack of a good groundplane. I suggest that you try a CB marine
antenna. These antennas are design to operator without a groundplane.
However, they are probably not design to handle high power. Looking at
shakespears webpage it looks like there antennas are limited to 25 watts
max. Well with in the range of a legal CB radio."

http://www.shakespeare-marine.com/index.html

what a long link

http://groups.google.com/groups?hl=e...N%26 tab%3Dwg


"Scott Downey" wrote in message
...
Are you saying it wont work?
Why would the manufacturer make a marine CB antenna knowing it would be

put
on a fiberglass boat knowing that most people would simply hook up the

coax
and see it it works.
I read in the marine catalogs about marine CB antennas designed for boats
and not to be concerned about a ground plane.
Anyone know the answer?


"Cecil Moore" wrote in message
...
Scott Downey wrote:
The boat is mostly wood and fiberglass, only metal is railings.


To what is the coax shield going to be tied? If that antenna is
an electrical 1/4 wavelength, where's the ground plane?
--
73, Cecil http://www.qsl.net/w5dxp



-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----





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