cb question
#21
Guest
Posts: n/a
Re: cb question
L.W.(ßill) ------ III wrote:
> Hi Greg,
> Nope! Now you know most everything about antennas:
> http://service.gm.com/techlineinfo/radio.html Which is to keep the
> transmitting antenna away from the car's computer.
And the coax and to power wires.
When the SWR is not 1:1, and the grounding is imperfect, some of the
RF will flow on the outside of the shield. The hot spots will be at
odd electrical quarterwaves of the operating frequency (234/Fmhz).
This is not to be confused with the false sense of security some
see by trimming the coax! (hahaha, don't fall for that). Inside
the coax, the electrical halfwave is 468/Fmhz*VF (velocity factor,
..66 for solid dielectric and .77 for foam dielectric). This is
frequency dependant, and any specific length is only for one
frequency. The coaxial electrical half wave will reflect the
exact impedance at the antenna feedpoint to the transmitter.
Any other location on the coax will be a different combination
of voltage and current lobes that will show the exact same SWR,
but since most meters read voltage, the apparent SWR will change
with the location of the meter in the coax.
If any of this doesn't make sense, post a reply and I'll try
to clear up any point that are unclear.
-Scott, CB'er since 1977, HAM since 2003, electronics tech since birth!
> Hi Greg,
> Nope! Now you know most everything about antennas:
> http://service.gm.com/techlineinfo/radio.html Which is to keep the
> transmitting antenna away from the car's computer.
And the coax and to power wires.
When the SWR is not 1:1, and the grounding is imperfect, some of the
RF will flow on the outside of the shield. The hot spots will be at
odd electrical quarterwaves of the operating frequency (234/Fmhz).
This is not to be confused with the false sense of security some
see by trimming the coax! (hahaha, don't fall for that). Inside
the coax, the electrical halfwave is 468/Fmhz*VF (velocity factor,
..66 for solid dielectric and .77 for foam dielectric). This is
frequency dependant, and any specific length is only for one
frequency. The coaxial electrical half wave will reflect the
exact impedance at the antenna feedpoint to the transmitter.
Any other location on the coax will be a different combination
of voltage and current lobes that will show the exact same SWR,
but since most meters read voltage, the apparent SWR will change
with the location of the meter in the coax.
If any of this doesn't make sense, post a reply and I'll try
to clear up any point that are unclear.
-Scott, CB'er since 1977, HAM since 2003, electronics tech since birth!
#22
Guest
Posts: n/a
Re: cb question
And that is the most important one too! I have seen dozens and heard of
a bunch more vehicles that have had severe onboard computer issues with
an improperly wired transmitter including an automatic TJ (I think it
was, or XJ) that went into neutral every time the owner keyed up his
mic.
The GM specs are the same for Chrysler vehicles, I phoned and asked
because installing systems was one of my jobs for a while. Fords can be
a real bitch with their computer controlled trannys too. Anti-lock
brakes go out 'real' easy too on most makes, but especially on GM's.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)
"L.W.(ßill) ------ III" wrote:
>
> Hi Greg,
> Nope! Now you know most everything about antennas:
> http://service.gm.com/techlineinfo/radio.html Which is to keep the
> transmitting antenna away from the car's computer.
> God Bless America, Bill O|||||||O
> mailto:-------------------- http://www.----------.com/
>
> Greg wrote:
> >
> > Now stop that Bill, that took an hour out of my day, now I know eveything
> > there is to know about antenas.
a bunch more vehicles that have had severe onboard computer issues with
an improperly wired transmitter including an automatic TJ (I think it
was, or XJ) that went into neutral every time the owner keyed up his
mic.
The GM specs are the same for Chrysler vehicles, I phoned and asked
because installing systems was one of my jobs for a while. Fords can be
a real bitch with their computer controlled trannys too. Anti-lock
brakes go out 'real' easy too on most makes, but especially on GM's.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)
"L.W.(ßill) ------ III" wrote:
>
> Hi Greg,
> Nope! Now you know most everything about antennas:
> http://service.gm.com/techlineinfo/radio.html Which is to keep the
> transmitting antenna away from the car's computer.
> God Bless America, Bill O|||||||O
> mailto:-------------------- http://www.----------.com/
>
> Greg wrote:
> >
> > Now stop that Bill, that took an hour out of my day, now I know eveything
> > there is to know about antenas.
#23
Guest
Posts: n/a
Re: cb question
And that is the most important one too! I have seen dozens and heard of
a bunch more vehicles that have had severe onboard computer issues with
an improperly wired transmitter including an automatic TJ (I think it
was, or XJ) that went into neutral every time the owner keyed up his
mic.
The GM specs are the same for Chrysler vehicles, I phoned and asked
because installing systems was one of my jobs for a while. Fords can be
a real bitch with their computer controlled trannys too. Anti-lock
brakes go out 'real' easy too on most makes, but especially on GM's.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)
"L.W.(ßill) ------ III" wrote:
>
> Hi Greg,
> Nope! Now you know most everything about antennas:
> http://service.gm.com/techlineinfo/radio.html Which is to keep the
> transmitting antenna away from the car's computer.
> God Bless America, Bill O|||||||O
> mailto:-------------------- http://www.----------.com/
>
> Greg wrote:
> >
> > Now stop that Bill, that took an hour out of my day, now I know eveything
> > there is to know about antenas.
a bunch more vehicles that have had severe onboard computer issues with
an improperly wired transmitter including an automatic TJ (I think it
was, or XJ) that went into neutral every time the owner keyed up his
mic.
The GM specs are the same for Chrysler vehicles, I phoned and asked
because installing systems was one of my jobs for a while. Fords can be
a real bitch with their computer controlled trannys too. Anti-lock
brakes go out 'real' easy too on most makes, but especially on GM's.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)
"L.W.(ßill) ------ III" wrote:
>
> Hi Greg,
> Nope! Now you know most everything about antennas:
> http://service.gm.com/techlineinfo/radio.html Which is to keep the
> transmitting antenna away from the car's computer.
> God Bless America, Bill O|||||||O
> mailto:-------------------- http://www.----------.com/
>
> Greg wrote:
> >
> > Now stop that Bill, that took an hour out of my day, now I know eveything
> > there is to know about antenas.
#24
Guest
Posts: n/a
Re: cb question
And that is the most important one too! I have seen dozens and heard of
a bunch more vehicles that have had severe onboard computer issues with
an improperly wired transmitter including an automatic TJ (I think it
was, or XJ) that went into neutral every time the owner keyed up his
mic.
The GM specs are the same for Chrysler vehicles, I phoned and asked
because installing systems was one of my jobs for a while. Fords can be
a real bitch with their computer controlled trannys too. Anti-lock
brakes go out 'real' easy too on most makes, but especially on GM's.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)
"L.W.(ßill) ------ III" wrote:
>
> Hi Greg,
> Nope! Now you know most everything about antennas:
> http://service.gm.com/techlineinfo/radio.html Which is to keep the
> transmitting antenna away from the car's computer.
> God Bless America, Bill O|||||||O
> mailto:-------------------- http://www.----------.com/
>
> Greg wrote:
> >
> > Now stop that Bill, that took an hour out of my day, now I know eveything
> > there is to know about antenas.
a bunch more vehicles that have had severe onboard computer issues with
an improperly wired transmitter including an automatic TJ (I think it
was, or XJ) that went into neutral every time the owner keyed up his
mic.
The GM specs are the same for Chrysler vehicles, I phoned and asked
because installing systems was one of my jobs for a while. Fords can be
a real bitch with their computer controlled trannys too. Anti-lock
brakes go out 'real' easy too on most makes, but especially on GM's.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)
"L.W.(ßill) ------ III" wrote:
>
> Hi Greg,
> Nope! Now you know most everything about antennas:
> http://service.gm.com/techlineinfo/radio.html Which is to keep the
> transmitting antenna away from the car's computer.
> God Bless America, Bill O|||||||O
> mailto:-------------------- http://www.----------.com/
>
> Greg wrote:
> >
> > Now stop that Bill, that took an hour out of my day, now I know eveything
> > there is to know about antenas.
#25
Guest
Posts: n/a
Re: cb question
And that is the most important one too! I have seen dozens and heard of
a bunch more vehicles that have had severe onboard computer issues with
an improperly wired transmitter including an automatic TJ (I think it
was, or XJ) that went into neutral every time the owner keyed up his
mic.
The GM specs are the same for Chrysler vehicles, I phoned and asked
because installing systems was one of my jobs for a while. Fords can be
a real bitch with their computer controlled trannys too. Anti-lock
brakes go out 'real' easy too on most makes, but especially on GM's.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)
"L.W.(ßill) ------ III" wrote:
>
> Hi Greg,
> Nope! Now you know most everything about antennas:
> http://service.gm.com/techlineinfo/radio.html Which is to keep the
> transmitting antenna away from the car's computer.
> God Bless America, Bill O|||||||O
> mailto:-------------------- http://www.----------.com/
>
> Greg wrote:
> >
> > Now stop that Bill, that took an hour out of my day, now I know eveything
> > there is to know about antenas.
a bunch more vehicles that have had severe onboard computer issues with
an improperly wired transmitter including an automatic TJ (I think it
was, or XJ) that went into neutral every time the owner keyed up his
mic.
The GM specs are the same for Chrysler vehicles, I phoned and asked
because installing systems was one of my jobs for a while. Fords can be
a real bitch with their computer controlled trannys too. Anti-lock
brakes go out 'real' easy too on most makes, but especially on GM's.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)
"L.W.(ßill) ------ III" wrote:
>
> Hi Greg,
> Nope! Now you know most everything about antennas:
> http://service.gm.com/techlineinfo/radio.html Which is to keep the
> transmitting antenna away from the car's computer.
> God Bless America, Bill O|||||||O
> mailto:-------------------- http://www.----------.com/
>
> Greg wrote:
> >
> > Now stop that Bill, that took an hour out of my day, now I know eveything
> > there is to know about antenas.
#26
Guest
Posts: n/a
Re: cb question
"Scotty" <ssargent@onewest.net> wrote in message
news:1141069529.145343.227570@p10g2000cwp.googlegr oups.com...
>I recently picked up a used Midland hand-held cb at a garage sale. I
> have not talked on the radio, but it seems to pick up cb traffic on the
> highway about a mile from my house just fine with the short antenna
> mounted to the radio. I understand the capabilities of this radio are
> limited. I am going to do some organized trail rides soon, and last
> year I noticed several of the Jeeps had cb radios, including the trail
> leaders and helpers. I understand that the trail leaders used the cb
> to point out things of interest as we went along. Have any of you used
> a hand-held cb on trail rides with just the standard antenna? How did
> it work?
>
They also pointed out direction changes. Thge hand held should be okay for
your first trip. Personally, I think it has overhead that you will learn is
hugely problematic. A built in CB is much better than the hand-held models.
#27
Guest
Posts: n/a
Re: cb question
"Scotty" <ssargent@onewest.net> wrote in message
news:1141069529.145343.227570@p10g2000cwp.googlegr oups.com...
>I recently picked up a used Midland hand-held cb at a garage sale. I
> have not talked on the radio, but it seems to pick up cb traffic on the
> highway about a mile from my house just fine with the short antenna
> mounted to the radio. I understand the capabilities of this radio are
> limited. I am going to do some organized trail rides soon, and last
> year I noticed several of the Jeeps had cb radios, including the trail
> leaders and helpers. I understand that the trail leaders used the cb
> to point out things of interest as we went along. Have any of you used
> a hand-held cb on trail rides with just the standard antenna? How did
> it work?
>
They also pointed out direction changes. Thge hand held should be okay for
your first trip. Personally, I think it has overhead that you will learn is
hugely problematic. A built in CB is much better than the hand-held models.
#28
Guest
Posts: n/a
Re: cb question
"Scotty" <ssargent@onewest.net> wrote in message
news:1141069529.145343.227570@p10g2000cwp.googlegr oups.com...
>I recently picked up a used Midland hand-held cb at a garage sale. I
> have not talked on the radio, but it seems to pick up cb traffic on the
> highway about a mile from my house just fine with the short antenna
> mounted to the radio. I understand the capabilities of this radio are
> limited. I am going to do some organized trail rides soon, and last
> year I noticed several of the Jeeps had cb radios, including the trail
> leaders and helpers. I understand that the trail leaders used the cb
> to point out things of interest as we went along. Have any of you used
> a hand-held cb on trail rides with just the standard antenna? How did
> it work?
>
They also pointed out direction changes. Thge hand held should be okay for
your first trip. Personally, I think it has overhead that you will learn is
hugely problematic. A built in CB is much better than the hand-held models.
#29
Guest
Posts: n/a
Re: cb question
"Scotty" <ssargent@onewest.net> wrote in message
news:1141069529.145343.227570@p10g2000cwp.googlegr oups.com...
>I recently picked up a used Midland hand-held cb at a garage sale. I
> have not talked on the radio, but it seems to pick up cb traffic on the
> highway about a mile from my house just fine with the short antenna
> mounted to the radio. I understand the capabilities of this radio are
> limited. I am going to do some organized trail rides soon, and last
> year I noticed several of the Jeeps had cb radios, including the trail
> leaders and helpers. I understand that the trail leaders used the cb
> to point out things of interest as we went along. Have any of you used
> a hand-held cb on trail rides with just the standard antenna? How did
> it work?
>
They also pointed out direction changes. Thge hand held should be okay for
your first trip. Personally, I think it has overhead that you will learn is
hugely problematic. A built in CB is much better than the hand-held models.
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Charles Ervin
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02-04-2007 11:01 PM
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