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Horrible feedback through stereo

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Mattx2
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Horrible feedback through stereo

Post by Mattx2 » Sunday, 24 October 2010, 20:43 PM

I am new to the cb world, so all help is welcomed.

I decided to put dads old cb in my 1999 silverado. Its a cobra 19ltd that he said he "turned it up", i hooked it to two 2' attennas that are attached to my toolbox. if the truck is off the cb works if the truck is on it screams and comes through the stereo. i do have a full stereo systems too subs, amp, cd player, the workers but i can turn it all off and it still comes through it.

Does anyone know how to fix this???

Ive tried grounding it better, hooking straight to the battery, turning the amp off and switching to nav.

Help please


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Re: Horrible feedback through stereo

Post by 231 » Sunday, 24 October 2010, 21:45 PM

First of all welcome to the forum.

I'd highly recommend you read through the Intro to Radios 101 section of the forum. In it there are tips on tuning the antenna(s), which I'd suggest you do (if you haven't already). That alone might help some.

You could try throwing some snap on ferrite beads on the speaker wires to help keep them from acting like antennas, but if the bleed over is as severe as you say, I'd guess that may not be enough. Assuming you are using the 75 ohm phasing harness provided with the kit, the antennas probably are not spaced properly and also may be too close to the cab. Antennas don't like being "next to metal" much. They prefer being above it. Although your tool box is under them, being next to the cab can create reflection in addition to what's already present from being and very short, un-tuned, and incorrectly spaced apart antenna sytem. I'm just speculating here based on your description and what I've seen most installations of cophased kits look like on 4 wheelers by the way...so please correct me if I'm wrong here.

But given those possibilities, I'd consider getting just a single piece of 50ohm coax and run only one of the two antennas. That should help make things easier in tuning and getting the antenna (at least one) to work properly. At only 2' of antenna length, that alone will make it tougher to tune...but with all the other stuff combined, it's likely to be impossible. You can leave the other antenna not hooked up and still give the look.

I hope it's as easy as throwing a couple of snap on ferrite beads on the speaker wires for you. That would be sweet. I honestly doubt that's going to be the case though.

Best of luck.

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Re: Horrible feedback through stereo

Post by jessejamesdallas » Monday, 25 October 2010, 5:20 AM

Turn off the Stereo when the CB is on....No More Problems......
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Re: Horrible feedback through stereo

Post by Night Crawler » Monday, 25 October 2010, 7:19 AM

Last edited by Night Crawler on Monday, 25 October 2010, 15:46 PM, edited 1 time in total.

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Re: Horrible feedback through stereo

Post by murdoc » Monday, 25 October 2010, 8:45 AM

jessejamesdallas wrote:Turn off the Stereo when the CB is on....No More Problems......
Thats my answer too!!!

I have major issues if I key my radio with the stereo on... Sounds like a bomb going off!!! :bom: ....

If I kill the stereo amp, JL HD600/4 Series driving JL 6.5" C5 components (rear) and a single JL 8-W7 sub bridged from the remaining 2 channels, I have no problems and can still listen through the 2 front speakers (JL C2 4") that are driven by the head unit (Alpine 9887) and a Alpine KTP-445 plug-n-play power pack...

I have a 225 amp marine disconnect under the passenger seat bottom of my daycab Peterbilt tractor just for that purpose... Reach over, flip up the seat bottom and kill the power... Works like a charm!!!


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Re: Horrible feedback through stereo

Post by Night Crawler » Monday, 25 October 2010, 11:38 AM

murdoc wrote:
jessejamesdallas wrote:Turn off the Stereo when the CB is on....No More Problems......
Thats my answer too!!!
It seems that he has the problem even with it turned off.
Mattx2 wrote: i do have a full stereo systems too subs, amp, cd player, the workers but i can turn it all off and it still comes through it.

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Re: Horrible feedback through stereo

Post by murdoc » Monday, 25 October 2010, 12:24 PM

murdoc wrote:It seems that he has the problem even with it turned off.

Mattx2 wrote:
i do have a full stereo systems too subs, amp, cd player, the workers but i can turn it all off and it still comes through it.
Mattx2, what stereo amp or amps are you using throughout your system??? What class amplifier are the??? Such as- class A, class C, Class D, etc... Full range/high pass/low range???

What happens if you unplug speaker wires AT the amplifier/amplifiers and key down your CB???

What I'm getting at is I would almost bet that most of or at least some of your issues are starting at your stereo amp/amps... Try a few different things to issolate the amps from the system... Unplug RCA's at both ends, Key down your CB, etc... You get the picture here...

Murdoc

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Re: Horrible feedback through stereo

Post by 'Doc » Monday, 25 October 2010, 16:16 PM

The simple fact is that there is RF getting into your stereo system. 'Curing' that isn't exactly simple, in fact it can be very aggravating.
The best way of doing it is by determining 'where', or how that RF is getting in and stopping it there. One way of doing that is by elimination, but since it happens even with the stereo off, that's not easy either. Try disconnecting things, the speakers to start with. Still getting squeals? then it's got to be because of the speaker wiring. Ferrite torroids might reduce or stop that. Figure on more than just one torroid on each speaker lead.
No squeal with the speakers disconnected? Then start looking at whatever is immediately 'before' those speakers, probably an amplifier of some kind. That's even more 'sticky' to deal with, it usually means by-passing that RF to ground at the input and outputs of the amplifier(s). That's typically done with capacitors, which can also affect audio quality/tone/etc. low values of capacitance tend to affect audio less than RF. Start with something like a 0.01uF cap of the appropriate voltage rating (the larger the better, think BIG voltages). That 0.01uF is a guess, try up/down from that too. If the caps reduce or stop the squealing, you've probably found the culprit. Still got a squeal? So, what's in 'front' of that/those amplifiers?
See how that's going? Do the 'end' devices first, then step back a step.
Shielded speaker wiring, and connecting wiring between 'devices' is a good idea. Then it's a matter of grounding, shielding, and by-passing. Keeping the RF carrying cables/devices as far from the stereo cables/devices is also a good idea (good luck with that!).
If all else fails, beat the @#$ things to death with a very large hammer. No, it doesn't 'cure' anything, but it sure as #3// makes you feel better!
Good luck!
- 'Doc

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Re: Horrible feedback through stereo

Post by Mattx2 » Monday, 25 October 2010, 18:31 PM

To 231, ok your just too good dad told me everything you just said. I haven't got to try anything yet but will.

Everyone that thinks its my amp causing the problem i unhooked my power cable at the battery..so my amp had nooo power to work...when i keyed down it still came through the speakers.

Murdoc its a 1400 watt diesel audio idk what class it is but i do have a 3 far capacitor.

Doc if me, dad, and the guy the cb shop can't get it working, im taking your advice. A hammer will be the smallest thing i use.

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Re: Horrible feedback through stereo

Post by wi11ie » Monday, 25 October 2010, 19:59 PM

Good Ol' Doc...
Docs Universal cure for my RF problem was ..Beat the snot outta it with a hammer..
Almost did..
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Re: Horrible feedback through stereo

Post by 'Doc » Monday, 25 October 2010, 21:26 PM

... or paint it pink. That works too.

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Re: Horrible feedback through stereo

Post by murdoc » Tuesday, 26 October 2010, 7:25 AM

Mattx2 wrote: i do have a 3 far capacitor
And I assume you discharged the cap after removing the positive cable from the battery post, right???

And in case you are wondering why I'm asking- two reasons, just removing the power supply lead from the battery is not the proper way to discharge a cap as the cap will still be charged unless you discharge it by means of resistor or bulb across positive and negative terminals of the capacitor itself...

murdoc

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Re: Horrible feedback through stereo

Post by Mattx2 » Friday, 29 October 2010, 20:27 PM

Thanks everyone for the help. I got it working.....

But it took me changing everything. A new cb, mounts, 3' antennas, and coax.

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Re: Horrible feedback through stereo

Post by rockyroad » Wednesday, 10 November 2010, 17:39 PM

i see youve fixed the problem, using my personal method of choice, but have fixed this issue with a low pass filter. my favorite, a bencher brand model ya1
life is like driving behind a van, u can't see a thing in front of u, but the people next to you can tell you whats coming.
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