Frank Gilliland wrote:
A 9' whip on the front bumper
isn't a bad choice either (don't forget to tie it back a bit so it
doesn't flop around).

Don't see many of those in these parts, but it might work.

--
http://www.allpar.com/mopar.html

In , Steveo
wrote:

Frank Gilliland wrote:
A 9' whip on the front bumper
isn't a bad choice either (don't forget to tie it back a bit so it
doesn't flop around).

Don't see many of those in these parts, but it might work.


It's not real popular, but I'm seeing it more and more -- probably due to the
increasing number of plastic tractors on the road.





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Frank Gilliland wrote:
In , Steveo
wrote:

Frank Gilliland wrote:
A 9' whip on the front bumper
isn't a bad choice either (don't forget to tie it back a bit so it
doesn't flop around).

Don't see many of those in these parts, but it might work.

It's not real popular, but I'm seeing it more and more -- probably due to
the increasing number of plastic tractors on the road.

See any on pickup trucks yet?

--
http://www.allpar.com/mopar.html

In , Steveo
wrote:

Frank Gilliland wrote:
In , Steveo
wrote:

Frank Gilliland wrote:
A 9' whip on the front bumper
isn't a bad choice either (don't forget to tie it back a bit so it
doesn't flop around).

Don't see many of those in these parts, but it might work.

It's not real popular, but I'm seeing it more and more -- probably due to
the increasing number of plastic tractors on the road.

See any on pickup trucks yet?


Just on the back bumper, and not too many of those. Seems everyone is so
paranoid about resale value these days that they are afraid to drill holes even
in the bumper. My Dodge has a 9' whip mounted dead center on the roo-guard right
above the winch, but I'm strange that way.




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Your SWR is high. High SWR isn't responsible for whine, but it is a good
indicator of other problems. From what you said in your other post your
cab roof
is fiberglass, so you don't have any ground plane -at all- for your
antenna. But
even that isn't responsible for the whine. I suspect that the radio isn't
very
well grounded. The mounting bracket should be bolted directly to the dash
or
some other chassis metal, and the negative power lead should be as short
as
possible (inches) to the same. You can also try a noise filter on your
positive
power lead, and tap the wire as close to the radio as possible. That
should
eliminate your whine. It should also get your SWR down below 3.

As for your antenna, you need to find a point on the rig where the antenna
can
be mounted directly to the chassis. A mirror mount is ok if the bracket
and door
are well grounded. A 9' whip on the front bumper isn't a bad choice either
(don't forget to tie it back a bit so it doesn't flop around). You could
also
try one of those 'no-ground-plane' antennas but don't expect great
results. Ask
around the watering holes and see what others have done.




I thought that because the whine went away when I disconnected the coax that
the problem was not related to the power supply and one of those noise
filters would not be of much use.
My biggest obstacle is that this is a company truck. The CB, radio and TV
are all using these antennas thru some kind of combiner. Running new coax
would mean drilling holes in the cab. I am not sure how my boss would feel
about this. If it were my truck I would rip it all out and start from
scratch but I must do the best I can with what I have.
The antennas are mirror mounts. I have been reading about grounding. I
thought that two antennas actually were better on the fiberglass vehicles
because they could create a ground plane between each other. My antennas use
a plastic insert to keep them from being grounded to the mirrors. If I
ground them would this short out the transmitter?

I appreciate your feedback Frank, I know that it is difficult to diagnose
something from a distance but I am willing to try anything except routing
new coax.

Frank Gilliland wrote:
In , Steveo
wrote:

Frank Gilliland wrote:
In , Steveo
wrote:

Frank Gilliland wrote:
A 9' whip on the front bumper
isn't a bad choice either (don't forget to tie it back a bit so it
doesn't flop around).

Don't see many of those in these parts, but it might work.

It's not real popular, but I'm seeing it more and more -- probably due
to the increasing number of plastic tractors on the road.

See any on pickup trucks yet?

Just on the back bumper, and not too many of those. Seems everyone is so
paranoid about resale value these days that they are afraid to drill
holes even in the bumper. My Dodge has a 9' whip mounted dead center on
the roo-guard right above the winch, but I'm strange that way.

They don't call em' power-wagons for nothing! I had one on the
back of my gmc for a little while, but it turned out to be a
pain in the ass, so I went to a center roof mount Wilson. I
can reach and un-screw it if I need to. It handles 300 watts
nicely.

--
http://www.allpar.com/mopar.html

In , "Randy" wrote:

snip
I thought that because the whine went away when I disconnected the coax that
the problem was not related to the power supply and one of those noise
filters would not be of much use.


You said the noise is not present on your broadcast radio, which tells me that
the noise isn't coming from the antenna. If the noise goes away when you
disconnect the coax then it must be being picked up by the coax shield. If the
coax shield were grounded then the CB would not hear the noise. Since the coax
shield is connected to the chassis of the CB, that means the CB isn't grounded
(by 'grounded' I mean an RF ground). The radio should be grounded by mounting it
directly to the metal chassis and using a very short negative power lead. The
noise filter helps prevent noise from any possible ground-loops or other RF
feedback paths.


My biggest obstacle is that this is a company truck. The CB, radio and TV
are all using these antennas thru some kind of combiner.


......yikes!


Running new coax
would mean drilling holes in the cab. I am not sure how my boss would feel
about this. If it were my truck I would rip it all out and start from
scratch but I must do the best I can with what I have.


Your boss wants you to deliver the payload in the shortest amount of time with
the least amount of hassles. To do your job well, local communication with a
good CB is -extremely- helpful, and almost essential for a long-haul driver.


The antennas are mirror mounts. I have been reading about grounding. I
thought that two antennas actually were better on the fiberglass vehicles
because they could create a ground plane between each other. My antennas use
a plastic insert to keep them from being grounded to the mirrors. If I
ground them would this short out the transmitter?


Dual antennas have no practical advantage over a single antenna in a mobile
installation. They do not create a ground plane between them, nor do they work
as a counterpoise to each other. They do look cool, but if I were you I would
just use one and avoid the hassle.

As for the antenna mount, the shield of the coax should be -well- connected to
the chassis (ground-plane), and the center conductor to the antenna. The plastic
insert is used to keep the two apart. If you disconnect the coax at the radio
and check it with an ohmmeter (center conductor to the shield), it should be
wide open; i.e, -not- shorted.


I appreciate your feedback Frank, I know that it is difficult to diagnose
something from a distance but I am willing to try anything except routing
new coax.


Don't spend -your- time or money -- convince your boss that you need a CB radio,
then get him to have his contracted radio shop do a proper installation. That's
what most trucking companies do, and I'm suprised your's doesn't.






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"Randy" wrote in message
...

"Steveo" wrote in message
...
"Randy" wrote:
I drive a 9900 International. I am getting a loud whine in the CB
speaker, but not in the radio speakers, even though they share the
dual
antennas. The whine increases and decreases with the rpms of the
motor.
After disconnecting the coax from the CB transceiver the whine is
gone.
Does this mean the coax or antennas are definitely the problem? ... or
are they just picking up on a problem with the alternator? The coax
will
be extremely hard to replace, maybe impossible since this is a company
truck. The alternator would probably be easier to repair.

Any help to eliminate or even reduce the whine would be greatly
appreciated.

Sounds like not enough ground on your antenna. How's your swr?

--
http://www.allpar.com/mopar.html


swr is ~ 3

I am just learning about CB radios. I know the antennas are using
plastic
inserts to keep them from being grounded.
I am using Firestik II antennas and have not tried adjusting them yet.
I
thought I needed to eliminate the whine first.
This International has a fiberglass top making for a bad ground plane,
from
what I have been reading.

That is about all I know of my situation.


SWR's to high. Try a "no ground" type of antenna, get the
SWR down below 2 or lower would be better.

Landshark


--
The world is good-natured to people
who are good natured.

"Frank Gilliland" wrote in message
...
In , "Randy" wrote:

snip
I thought that because the whine went away when I disconnected the coax
that
the problem was not related to the power supply and one of those noise
filters would not be of much use.


You said the noise is not present on your broadcast radio, which tells me
that
the noise isn't coming from the antenna. If the noise goes away when you
disconnect the coax then it must be being picked up by the coax shield. If
the
coax shield were grounded then the CB would not hear the noise. Since the
coax
shield is connected to the chassis of the CB, that means the CB isn't
grounded
(by 'grounded' I mean an RF ground). The radio should be grounded by
mounting it
directly to the metal chassis and using a very short negative power lead.
The
noise filter helps prevent noise from any possible ground-loops or other
RF
feedback paths.


My biggest obstacle is that this is a company truck. The CB, radio and TV
are all using these antennas thru some kind of combiner.


.....yikes!


Running new coax
would mean drilling holes in the cab. I am not sure how my boss would
feel
about this. If it were my truck I would rip it all out and start from
scratch but I must do the best I can with what I have.


Your boss wants you to deliver the payload in the shortest amount of time
with
the least amount of hassles. To do your job well, local communication with
a
good CB is -extremely- helpful, and almost essential for a long-haul
driver.


The antennas are mirror mounts. I have been reading about grounding. I
thought that two antennas actually were better on the fiberglass vehicles
because they could create a ground plane between each other. My antennas
use
a plastic insert to keep them from being grounded to the mirrors. If I
ground them would this short out the transmitter?


Dual antennas have no practical advantage over a single antenna in a
mobile
installation. They do not create a ground plane between them, nor do they
work
as a counterpoise to each other. They do look cool, but if I were you I
would
just use one and avoid the hassle.

As for the antenna mount, the shield of the coax should be -well-
connected to
the chassis (ground-plane), and the center conductor to the antenna. The
plastic
insert is used to keep the two apart. If you disconnect the coax at the
radio
and check it with an ohmmeter (center conductor to the shield), it should
be
wide open; i.e, -not- shorted.


I appreciate your feedback Frank, I know that it is difficult to
diagnose
something from a distance but I am willing to try anything except routing
new coax.


Don't spend -your- time or money -- convince your boss that you need a CB
radio,
then get him to have his contracted radio shop do a proper installation.
That's
what most trucking companies do, and I'm suprised your's doesn't.




Just so I am clear about one thing .... In all of these articles that I
have been reading, when they talk about grounding the antenna, they are
referring to a RF ground (ground plane) and not a physical ground? If for
some reason the shield is not grounded would this be my problem?

My boss will not care that this unit has a whine. I am not sure he would
care whether it has a CB or not. I had to take the truck down to the shop
last week to get the steer tires balanced, I had to pay for everything. He
is not a bad guy ... just cheap!

The unit might not be grounded very good. It sits in an upper header
console, just strapped in not bolted. I will ground the unit and purchase a
noise filter then adjust my antennas.

I tried reading as many articles as I could but they all were saying the
same things and some of that I could not understand. I thank you for your
time. I will let you know if the problem persist after these changes.

Thanks again

You should be able to remove the plastic inserts where the antennas are
mounted. You may also have a problem with the splitter that allows the
stereo and TV to use the same antennas. Maybe you can use one antenna for
the CB and the other for everything else. As for the whine, I agree with
everyone else. Once the antennas are working properly, it may go away.

Chris
"Randy" wrote in message
...

"Frank Gilliland" wrote in message
...
In , "Randy" wrote:

snip
I thought that because the whine went away when I disconnected the coax
that
the problem was not related to the power supply and one of those noise
filters would not be of much use.


You said the noise is not present on your broadcast radio, which tells
me
that
the noise isn't coming from the antenna. If the noise goes away when you
disconnect the coax then it must be being picked up by the coax shield.
If
the
coax shield were grounded then the CB would not hear the noise. Since
the
coax
shield is connected to the chassis of the CB, that means the CB isn't
grounded
(by 'grounded' I mean an RF ground). The radio should be grounded by
mounting it
directly to the metal chassis and using a very short negative power
lead.
The
noise filter helps prevent noise from any possible ground-loops or other
RF
feedback paths.


My biggest obstacle is that this is a company truck. The CB, radio and
TV
are all using these antennas thru some kind of combiner.


.....yikes!


Running new coax
would mean drilling holes in the cab. I am not sure how my boss would
feel
about this. If it were my truck I would rip it all out and start from
scratch but I must do the best I can with what I have.


Your boss wants you to deliver the payload in the shortest amount of
time
with
the least amount of hassles. To do your job well, local communication
with
a
good CB is -extremely- helpful, and almost essential for a long-haul
driver.


The antennas are mirror mounts. I have been reading about grounding. I
thought that two antennas actually were better on the fiberglass
vehicles
because they could create a ground plane between each other. My
antennas
use
a plastic insert to keep them from being grounded to the mirrors. If I
ground them would this short out the transmitter?


Dual antennas have no practical advantage over a single antenna in a
mobile
installation. They do not create a ground plane between them, nor do
they
work
as a counterpoise to each other. They do look cool, but if I were you I
would
just use one and avoid the hassle.

As for the antenna mount, the shield of the coax should be -well-
connected to
the chassis (ground-plane), and the center conductor to the antenna. The
plastic
insert is used to keep the two apart. If you disconnect the coax at the
radio
and check it with an ohmmeter (center conductor to the shield), it
should
be
wide open; i.e, -not- shorted.


I appreciate your feedback Frank, I know that it is difficult to
diagnose
something from a distance but I am willing to try anything except
routing
new coax.


Don't spend -your- time or money -- convince your boss that you need a
CB
radio,
then get him to have his contracted radio shop do a proper installation.
That's
what most trucking companies do, and I'm suprised your's doesn't.




Just so I am clear about one thing .... In all of these articles that I
have been reading, when they talk about grounding the antenna, they are
referring to a RF ground (ground plane) and not a physical ground? If for
some reason the shield is not grounded would this be my problem?

My boss will not care that this unit has a whine. I am not sure he would
care whether it has a CB or not. I had to take the truck down to the shop
last week to get the steer tires balanced, I had to pay for everything. He
is not a bad guy ... just cheap!

The unit might not be grounded very good. It sits in an upper header
console, just strapped in not bolted. I will ground the unit and purchase
a
noise filter then adjust my antennas.

I tried reading as many articles as I could but they all were saying the
same things and some of that I could not understand. I thank you for your
time. I will let you know if the problem persist after these changes.

Thanks again