| cb antenna advice sought [message #99606] |
Mon, 13 September 2010 15:37  |
Dave Martin
Messages: 59
Registered: May 2010
Location: Ames Iowa Home Base
Karma: 0
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I bought a Cobra 75 wx st "all in one" CB radio for occasional use while driving.
I need to add a CB antenna to my GMC coach. My intended use is for local communications about traffic jams etc...I'm not seeking long range performance.
Is it reasonable to use a mirror mounted antenna?
If so, must I buy a mirror mount antenna that specifically says "no ground plane", or would any mirror mount antenna likely be ok?
Should I use an extra post to get the antenna up in the air to avoid interference with the coach body?
If a mirror mount antenna won't be suitable, what would you recommend?
Dave
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| Re: cb antenna advice sought [message #99613 is a reply to message #99610] |
Mon, 13 September 2010 17:04  |
Larry C
Messages: 1168
Registered: July 2004
Location: NE Illinois by the Illino...
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I agree, try to search. But lots of the search topics disappear so I will do a short comment.
As far as I know with the mirror mounted antenna, they use a high loaded antenna, they don't rely on a ground plane and usually can tell one because there is a coil of wire on the antenna.
For many years now I have used an antenna that sticks to the glass. A little black box stick to the glass on the inside opposite the outside foot. They have been great as long as you do not put a Linear Amplifier to boost your power.
Some put the antenna on the front roof rack in the center. It will benefit by the aluminum roof metal and probably work the best.
Hopefully you will be able to get something from the archive search
good luck
Gatsbys' CRUISER  08-18-04
74 GLACIER X, 260/455-APC-4 Bagg'r
Remflex Manifold gaskets
CampGrounds needed, Add yours to "PLACES" />
http://www.gmceast.com/travel
_
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| Re: [GMCnet] cb antenna advice sought [message #99619 is a reply to message #99613] |
Mon, 13 September 2010 18:24 |
k2gkk
Messages: 4452
Registered: November 2009
Karma: -8
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Senior Member |
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Just for clarification, EVERY CB antenna that is
less than 105-108" tall needs to have a coil in
it somewhere! This is what makes the antenna
resonant; think organ pipes that are different
lengths for each pitch. CB antennas that are
ELECTRICALLY (not physically) about 210-216"
tall will not requre a ground plane.
Always, the less coil required to compensate
for a physically shortened antenna, the better
the antenna will radiate and receive. The same
applies regarding the height above ground. A
shorter (with loading coil) antenna on the top
of the tremendous ground plane offered by the
metal roof of the GMC coach is likely to perform
much better than a full-length whip that's mounted
down low.
BTW, I would NEVER use a "through-tghe-glass"
antenna if I could avoid it.
** D C "Mac" Macdonald **
* m/v Another Adventure *
** '95 Carver 355 ACMY **
* Grand Lake - Oklahoma *
** AGLCA (#217) & USPS **
** USAF & FAA, Retired **
** Amateur Radio K2GKK **
* "An unarmed man can but flee *
* from evil. Evil can NEVER be *
* overcome by flight FROM it." *
To: gmclist@temp.gmcnet.org
From: slawrence111@yahoo.com
Date: Mon, 13 Sep 2010 17:04:19 -0500
Subject: Re: [GMCnet] cb antenna advice sought
I agree, try to search. But lots of the search topics
disappear so I will do a short comment.
As far as I know with the mirror mounted antenna, they
use a high loaded antenna, they don't rely on a ground
plane and usually can tell one because there is a coil
of wire on the antenna.
For many years now I have used an antenna that sticks
to the glass. A little black box stick to the glass on
the inside opposite the outside foot. They have been
great as long as you do not put a Linear Amplifier to
boost your power.
Some put the antenna on the front roof rack in the center.
It will benefit by the aluminum roof metal and probably
work the best.
Hopefully you will be able to get something from the
archive search
good luck
--
Gatsbys' CRUISER :d
74 GLACIER X, 260
455/APC/4 bagg'r(ver3)
Remflex Manifold gaskets
_______________________________________________
Purchased 08-18-04
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| Re: [GMCnet] cb antenna advice sought [message #99634 is a reply to message #99619] |
Mon, 13 September 2010 20:07 |
Jim White[1]
Messages: 144
Registered: September 2008
Karma: 0
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Senior Member |
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Mac-
Please just tell us what antenna to buy if we are going to do a roof
mount and screw it into the aluminum frame of the GMC.
I removed two rear view mirrow mounts and threw away dozens of feet of
cable stuffed under the dash. There has to be a better way to go.
Does Radio Shack sell something good for the GMC. If so what?
I need to buy and install one in the next ten days.
Thanks-
Jim "Doc" White (Doc the impatient one)
Wintergreen, VA
75 GMC (with new CB and no antenna)
***************
On 9/13/2010 7:24 PM, D C *Mac* Macdonald wrote:
> Just for clarification, EVERY CB antenna that is
> less than 105-108" tall needs to have a coil in
> it somewhere! This is what makes the antenna
> resonant; think organ pipes that are different
> lengths for each pitch. CB antennas that are
> ELECTRICALLY (not physically) about 210-216"
> tall will not requre a ground plane.
>
> Always, the less coil required to compensate
> for a physically shortened antenna, the better
> the antenna will radiate and receive. The same
> applies regarding the height above ground. A
> shorter (with loading coil) antenna on the top
> of the tremendous ground plane offered by the
> metal roof of the GMC coach is likely to perform
> much better than a full-length whip that's mounted
> down low.
>
> BTW, I would NEVER use a "through-tghe-glass"
> antenna if I could avoid it.
>
>
> ** D C "Mac" Macdonald **
> * m/v Another Adventure *
> ** '95 Carver 355 ACMY **
> * Grand Lake - Oklahoma *
> ** AGLCA (#217)& USPS **
> ** USAF& FAA, Retired **
> ** Amateur Radio K2GKK **
>
>
> * "An unarmed man can but flee *
> * from evil. Evil can NEVER be *
> * overcome by flight FROM it." *
>
>
>
>
>
> To: gmclist@temp.gmcnet.org
> From: slawrence111@yahoo.com
> Date: Mon, 13 Sep 2010 17:04:19 -0500
> Subject: Re: [GMCnet] cb antenna advice sought
>
> I agree, try to search. But lots of the search topics
> disappear so I will do a short comment.
>
> As far as I know with the mirror mounted antenna, they
> use a high loaded antenna, they don't rely on a ground
> plane and usually can tell one because there is a coil
> of wire on the antenna.
>
> For many years now I have used an antenna that sticks
> to the glass. A little black box stick to the glass on
> the inside opposite the outside foot. They have been
> great as long as you do not put a Linear Amplifier to
> boost your power.
>
> Some put the antenna on the front roof rack in the center.
> It will benefit by the aluminum roof metal and probably
> work the best.
>
> Hopefully you will be able to get something from the
> archive search
>
> good luck
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| Re: [GMCnet] cb antenna advice sought [message #99638 is a reply to message #99634] |
Mon, 13 September 2010 20:25 |
k2gkk
Messages: 4452
Registered: November 2009
Karma: -8
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Senior Member |
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Hi, Doc (and others).
I really don't have a handle on what is available
for CB usage. My "shtick" is ham stuff.
Having said that, if you still have at least ONE
of the mirror mounts using a 3/8" x 24 thread, I
would suggest using the longest "Fire-Stik" you
can buy that won't snag on trees and bridges. The
Fire-Stik antennas (in my opinion) are about the
best you can get without using the ~ 9 foot steel
whips. I recommend using the "real McCoy" rather
than one of the knock-offs.
If you had two antennas mounted previously, that
extra coax wadded up under the dash truly WAS
necessary to the performance of the dual system.
It's too complicated to easily explain here, but
those two antennas were hooked up in parallel
(like parallel batteries) and the lengths of
coax from each antenna to the junction were of
special impedance and specific length to convert
the paralleled antennas to the normal coax and
CB transceiver.
In general, you are generally wanting to know
what is ahead of you, so mounting the antenna up
forward won't hurt your overall performance that
much.
I'm not familiar enough with how the GMC skin is
put together to confidently suggest a top-mounted
antenna. I believe Tram, Larsen, and several other
makers sell base-loaded (coil at bottom instead of
up in the middle) shorter antennas with several
styles of mountings. The "NMO" mount is quite
common and I have several ham VHF and UHF antennas
that use that NMO mounting system. The antennas
can simply unscrew from the mount if necessary.
Of course, reaching a roof-mounted antenna on a
GMC is a bit problematical, eh?
My "Money Pit" has a well-known brand CB antenna
mounted on the left-side mirror, but I don't know
where the coax is and the actual CB set that came
with the coach is not apparently hooked up either.
Projects, projects, projects!!!
I hope that is of some assistance. Basically, you
want to use an antenna with the least amount of
coil (causes at least SOME signal loss) and mounted
as high as practical.
A truly professional CB shop/installer may be your
best choice.
Best wishes and good luck.
~ ~ ~ ~ ~ ~ ~ ~ ~
~ Mac Macdonald ~
~ Hamcall K2GKK ~
~ Oklahoma City ~
~~ "Money Pit" ~~
~ '76 ex - P.B. ~
~ ~ ~ ~ ~ ~ ~ ~ ~
* "An unarmed man can but flee *
* from evil. Evil can NEVER be *
* overcome by flight FROM it." *
----------------------------------------
Date: Mon, 13 Sep 2010 21:07:37 -0400
From: jameswwhite@cyberwind.net
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] cb antenna advice sought
Mac-
Please just tell us what antenna to buy if we are going to do a roof
mount and screw it into the aluminum frame of the GMC.
I removed two rear view mirrow mounts and threw away dozens of feet of
cable stuffed under the dash. There has to be a better way to go.
Does Radio Shack sell something good for the GMC. If so what?
I need to buy and install one in the next ten days.
Thanks-
Jim "Doc" White (Doc the impatient one)
Wintergreen, VA
75 GMC (with new CB and no antenna)
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| Re: [GMCnet] cb antenna advice sought [message #99665 is a reply to message #99619] |
Mon, 13 September 2010 22:34 |
Larry C
Messages: 1168
Registered: July 2004
Location: NE Illinois by the Illino...
Karma: 0
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Senior Member |
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BTW, I would NEVER use a "through-tghe-glass"
antenna if I could avoid it.
____________________________________________________________
Why would you say that?
I have used them on many vehicles for years and they perform just fine.
Do you have a ligit reason for dissing an easy to install CB Antenna???
Just wondering.
Gatsbys' CRUISER 08-18-04
74 GLACIER X, 260/455-APC-4 Bagg'r
Remflex Manifold gaskets
CampGrounds needed, Add yours to "PLACES" />
http://www.gmceast.com/travel
_
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|
|
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| Re: cb antenna advice sought [message #99669 is a reply to message #99606] |
Mon, 13 September 2010 22:55 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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Take a look here.
http://www.claysradioshop.com/antennas-base_load.htm
Any of the first 4 mounted on the center of your GMC roof will work well. I do not like these prices but This is the best design I would recommend for the top of a GMC. I'll keep looking for some cheaper base loaded non-,magnetic mount ones.
I'll also look in my junk at home. I just might have an old base loaded CB one. There was one on my coach when I got it and I immediately took it off. I used the roof mount and coax for a good ham radio antenna. I know the radio went into the garbage but I might have kept the antenna. I'll look when I get home.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] cb antenna advice sought [message #99688 is a reply to message #99665] |
Tue, 14 September 2010 07:15 |
k2gkk
Messages: 4452
Registered: November 2009
Karma: -8
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Senior Member |
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I want a direct connection between my transmitter
and the antenna. The through-the-glass antennas
depend upon coupling power from a small conducting
plate on the inside of the windshield to another
small plate on the outside of the windshield.
Does it work? Sort of.
I did NOT say I would never use one. I never have.
I have always found a better way.
~ ~ ~ ~ ~ ~ ~ ~ ~
~ Mac Macdonald ~
~ Hamcall K2GKK ~
~ Oklahoma City ~
~~ "Money Pit" ~~
~ '76 ex - P.B. ~
~ ~ ~ ~ ~ ~ ~ ~ ~
> To: gmclist@temp.gmcnet.org
> From: slawrence111@yahoo.com
> Date: Mon, 13 Sep 2010 22:34:27 -0500
> Subject: Re: [GMCnet] cb antenna advice sought
>
>
>
> BTW, I would NEVER use a "through-tghe-glass"
> antenna if I could avoid it.
> ____________________________________________________________
>
>
> Why would you say that?
>
> I have used them on many vehicles for years and they perform just fine.
>
> Do you have a ligit reason for dissing an easy to install CB Antenna???
>
> Just wondering.
>
>
> --
> Gatsbys' CRUISER :d
> 74 GLACIER X, 260
> 455/APC/4 bagg'r(ver3)
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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