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CB Radio/Car Stereo sharing CB Antenna?

JPOutfitters

JPOutfitters

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I researched a little over the internet and a few people said it was possible over at the CB Radio Talk Forums online....so........I got a "T" yesterday for the back of my CB radio, an RCA type end that pops into the back of my car stereo, and a 2 foot coax. I put the RCA end on and put the coax into my car stereo and ran it down behind the dash to my CB radio and screwed it onto the "T". Then I screwed my antenna coax onto the other end of the "T".

$15 for the connections and the 2 foot coax and it's done. I have no static over the CB or the Car Stereo with both on at the same time. It seems to work perfect.:D

I purchased all of the connections and the coax at Radio Shack!
 
are you running 2 cb antennas or a cb antenna and a car stereo antenna? I'm actually getting better reception here in the mountains above 8000 feet where I live for my car stereo now!
 
JPOutfitters said:
I researched a little over the internet and a few people said it was possible over at the CB Radio Talk Forums online....so........I got a "T" yesterday for the back of my CB radio, an RCA type end that pops into the back of my car stereo, and a 2 foot coax. I put the RCA end on and put the coax into my car stereo and ran it down behind the dash to my CB radio and screwed it onto the "T". Then I screwed my antenna coax onto the other end of the "T".

$15 for the connections and the 2 foot coax and it's done. I have no static over the CB or the Car Stereo with both on at the same time. It seems to work perfect.:D

I purchased all of the connections and the coax at Radio Shack!
Click to expand...


Have you checked your SWR?
 
just calibrated on chanel 20 and I'm at less than 1.5 SWR........and that's with the car stereo on at the same time!
 
Dang... May have to look into that for Julie's Suburban. I wonder if that 4 watts is enough power to do any damage to a car stereo receiver with long-term use?
 
not sure about the long term effect on the stereo yet.......but I do know that when I key in while the radio and the stereo are both on I get no cross feed between the two! It seems to be working just fine. I just spent 8 hours on the road today picking up and dropping off some parts to a buddy in New Mexico and I had it going with the truckers all day! Works like a dream.....:waytogo:
 
You really need a diplexer to separate the 27 MHz from the 90 MHz.

Otherwise, when you transmit on the CB, you are really feeding 4 watts into your stereo receiver, which it is not designed to handle.
 
Unless you're physically unplugging the coax, you're still sending RF energy down the line, and into your receiver. And if you do unplug the coax, you've created a tuning stub that will do very strange things to the characteristics of your feed line.

Your setup may just happen to work for you, maybe your car stereo has some awesome rejection capabilities. I wouldn't run around recommending this to anyone though, not unless a diplexer is used.
 
To each his own.......seems to me like you have a bug up your "asset" and just want to prove somebody right or wrong! :dunno:

I simply posted that I did it and it works! You can't say that it doesn't work.....because it is. Therefore I will take what you have to say and "Dually Notate" it. :rolleyes:

As far as anyone else reading this, I've made it work with a CHEAP car stereo and since the day that I posted this it has worked like a charm! Should you chose to get a diplexer and go that route then I'm sure it will work that way too. :pimp:

As far as recommendations go......I think people should post their "opinion" and notate that it's an "opinion" unless you can show proof that your "opinion" is an actual fact!

Opinions are like A-holes.........you know the rest, and if you don't then keep wondering why you don't have many friends! Unless your extensive ring of friends is over the internet and you've spent the better part of a decade with "friends" that also sit around posting in a forum with your obvious extensive knowledge of all things as well. :bow:

I will continue to utilize my set up. :D
 
What I claim as fact requires almost a year of coursework in electromagnetics to discuss the underlying theory.

In a nutshell:

A transmission line is designed to transmit power from a generator to a load. The generator can either be something like the power plant, your CB, or an antenna. So long as all the impedances match (generally 50 ohms for RF type stuff, unless it's TV coax type stuff at 75 ohms). An impedance match guarantees 100% transmission.

When you put loads in parallel on a transmission line, with matched impedances, it functions very similar to a parallel circuit in circuit theory. Part of the energy will go to each load (in this case, your antenna and your car stereo).

However, when there is an impedance mismatch, there is a certain degree of reflected power. This is determined by the reflection coefficient. If your transmission line has impedance Z0 and your load has impedance Z1, the reflection coefficient, Gamma = (Z1 - Z0)/(Z1 + Z0). The transmission coefficient is 1-Gamma. That is, whatever is not reflected is transmitted. (An open circuit at the end of a transmission line guarantees 100% reflection, as does a short-circuit).

So, if you were to unplug the coax from your stereo and leave it dangling, that would create a reflection. When Gamma != 0, the actual impedance of a length of transmission line becomes dependent on its length, and the wavelength (in the dielectric) of the signal transmitted through it.

Nonetheless, while this coax is attached to your stereo, unless your stereo presents an open circuit to the coax (which would be silly, because it wouldn't work), or if it presents a short circuit, and you have a quarter-wave section of transmission line (which is by nature an impedance inverter), there will be power transmitted to the stereo.

Generally speaking, most radios have sensitivities on the order of microvolts. These microvolts are caused by conversion of the electromagnetic wave into currents along the antenna. The power density of a received radio wave is generally on the order of microwatts. The 4 watt output of your CB transciever is 6 orders of magnitude greater.


I tried to summarize it for you, and provide a positive solution.

Like I said, it could be that your stereo unit is capable of rejecting that much RF energy... or it could be a matter of time before it fails.
 
Okay, now that I got the facts of the matter out of the way I can deal with your opinionated asshattery here:


JPOutfitters said:
To each his own.......seems to me like you have a bug up your "asset" and just want to prove somebody right or wrong! :dunno:
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Incorrect. I was just trying to shed some light on why what you're doing may not be such a great idea.

Evidently this mean I just have a bug up my ass and a chip on my shoulder....

I simply posted that I did it and it works! You can't say that it doesn't work.....because it is. Therefore I will take what you have to say and "Dually Notate" it. :rolleyes:
Click to expand...

Nowhere did I say it doesn't work, I just stated that your car radio is now receiving a significant amount of RF energy compared to what it was designed for


As far as recommendations go......I think people should post their "opinion" and notate that it's an "opinion" unless you can show proof that your "opinion" is an actual fact!
Click to expand...

See above FACTS.

Are you going to go through every single thread on this board and filter out the opinion and fact for everyone? You don't appear to be doing too good of a job here.

Opinions are like A-holes.........you know the rest, and if you don't then keep wondering why you don't have many friends! Unless your extensive ring of friends is over the internet and you've spent the better part of a decade with "friends" that also sit around posting in a forum with your obvious extensive knowledge of all things as well. :bow:
Click to expand...

Allright Dr. Phil. Whatever you say :rolleyes:


I will continue to utilize my set up. :D
Click to expand...

Sounds like a plan.
 
Jagged said:
Okay, now that I got the facts of the matter out of the way I can deal with your opinionated asshattery here:




Incorrect. I was just trying to shed some light on why what you're doing may not be such a great idea.

Evidently this mean I just have a bug up my ass and a chip on my shoulder....



Nowhere did I say it doesn't work, I just stated that your car radio is now receiving a significant amount of RF energy compared to what it was designed for




See above FACTS.

Are you going to go through every single thread on this board and filter out the opinion and fact for everyone? You don't appear to be doing too good of a job here.



Allright Dr. Phil. Whatever you say :rolleyes:




Sounds like a plan.
Click to expand...


So basicly you can look things up and "summarize" correct answers to try and make yourself look good...:bow:

and then you quote me making yourself look like a douche!! :whistle:

So take your "FACTS" and your "OPINION" and get the F_ck out of my thread!!!

:popcorn:
 
JPOutfitters said:
So basicly you can look things up and "summarize" correct answers to try and make yourself look good...:bow:

and then you quote me making yourself look like a douche!! :whistle:

So take your "FACTS" and your "OPINION" and get the F_ck out of my thread!!!

:popcorn:
Click to expand...

Seriously dude?
 
jp, not to sound like I'm defending Jagged but calm down man. All he's done is tell you why you shouldn't do something based on his knowledge of facts.

Uhmmmm...I know nothing about this stuff but Jagged, aren't you going to a University for Electrical Engineering and other crap? Then there's the HAM stuff...
 
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