Forum Index
Jeep Horizons HomeLinksJeep Horizons Tech Write-upsJeep newsLand useContact

 Watched TopicsWatched Topics   FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

Constant CB whine


 
Post new topic   Reply to topic     Forum Index -> Electronic
View previous topic :: View next topic  
Author Message
2kjhouse
Member


Joined: 18 Jan 2005
Location: Davis Junction, IL

PostPosted: Tue Jan 18, 2005 4:35 pm    Post subject: cb install Reply with quote

I have a cobra cb and it has a constant whine like what would come from a electric fuel pump at low squelch levels. I have a 4" firestick with most of the antenna above the kj, it is mounted on my spare tire mount and grounded to the chassis with fused power at the battery. If I remove the antenna from the kj it still whines, but when I move it about a foot away from the kj it stops, could thei be ground plane problem or rf interference coming in the antenna? The swr is 1.2 so that is good but still the noise, also when I was driving in the heavy snow the noise stopped like it was a bad ground somewher but I wouldn't know where, I tried a direct groung to the battery, the frame and to the firewall but no difference, any help is appreciated.

Brian
_________________
2003 Patriot Blue 4x4 Limited Patriot Edition
Lost # 00529
265/70-16 Bridgestone Dueller Revos / Rusty's 2.5 coil lift,Aries Nerf bars,Outland brush bar
Helix TBS w/ K&N FIPK, homemade disconnects
Tracklok diff,Tow Hooks,KC 100 watt HiLighters
Back to top
View user's profile Send private message Visit poster's website
Drake69
Member


Joined: 26 Mar 2004
Location: Stormtroopin....

PostPosted: Tue Jan 18, 2005 7:52 pm    Post subject: Re: cb install Reply with quote

That does sound like a bad ground somewhere. A few things you can do to try and fix it....

1: Change the point where you're grounding, even if you think you're on the frame it might not be enough.

2: Change the location of the aerial mount higher than it's current location. Your interference could be coming from the frame because the KJ's body structure is interfering with a clear, straight-line signal.

3: Go to Radio Shack and pick up a power relay box for CBs that goes on the hot wire between the CB and the positive battery. The relay will help suppress engine noise-bleed that is common RF interference in any vehicle.

NOTE: I had similar problems to what you're describing, but after doing all those things I listed, I now get a nice clean signal. And I'm connected to the fuse box under the dashboard, not the battery terminal under the hood!!!
_________________

Back to top
View user's profile Send private message
ThePhantum
Pissed-Off Admin
Pissed-Off Admin


Joined: 23 Jan 2004
Location: I knew it...I'm surrounded by Assholes!

PostPosted: Tue Jan 18, 2005 7:52 pm    Post subject: Reply with quote

I split this off from the CB radio thread since it's a specific problem.

If it is a constant steady whine, it sounds like either the cable or mount is picking up RF interference. Since when you move the antenna away from the Jeep it stops, I would suspect either the mount itself or the termination (at the mount end of the cable) has an RF hole...if it's a quality mount, I would check the termination first. You could also try putting an RF filter on the power line, since it could be ignition noise too...but I kind of doubt it.

HTH

Steve
_________________

97 XJ Sport with a bunch of stuff
Quote:
Never argue with idiots, they drag you down to their level and beat you with experience
Back to top
View user's profile Send private message AIM Address Yahoo Messenger MSN Messenger
quadna71
Member


Joined: 02 Jan 2004
Location: Delaware

PostPosted: Fri Apr 15, 2005 4:39 pm    Post subject: Reply with quote

not to piggy back on another thread...but how about when the whine is directly correlated to engine rpm? i just installed a new radio in my jeep tonight - 1.2, 1.4 swr readings (channels 1 & 40 respectively) and it seems to work well. but when i started up the jeep i noticed i had to crank the squelch and gain much more to compensate for the engine whine. will that power relay box you (Drake69) were talking about kill that whine without killing my signal? my power and ground come direct from the battery, radio chassis is grounded, antenna mount is frame grounded, brand new RG-8x coax and a new uniden PRO538W. any ideas?
thanks,
chris

p.s. i'll probably mess around with it all tomorrow in the daylight again. i just called it a night once the sun disappeared. oh, anyone interested in a used 75wxST? Smile
_________________
2003 TJ Sport
Back to top
View user's profile Send private message Send e-mail
IBTJn
Moderator
Moderator


Joined: 31 Dec 2004
Location: Just Outside of Portland, OR

PostPosted: Fri Apr 15, 2005 9:21 pm    Post subject: Reply with quote

Indeed, I'd certainly run another separate ground wire from your mount to the chasis. #14 stranded ought to be sufficient. Secondly, I'd consider wiring directly to the battery using This Linky. Using coax as the power supply wire alone may solve the problem...especially if the RFI is from an unknown location and coming in through the power supply line. If this doesn't quite cut it, then I'd use the power filter.

One other thing, I could be wrong but I'd bet it's noise from the fuel pump. Don't know about your KJ, but my wife's XJ's tailgate is fiberglass...which means it's invisible to RF energy (including interference and/or harmonics). As you probably know the fuel pump is likely inside the fuel tank, and RFI can reflect, just like a radio signal. That being the case, I'd relocate the mount to the front fender (different mount required probably) rather than the back. But that's just me. Personally, I believe the ground planing (propagation) of the antenna would be more circular in nature anyway, giving your transmit/recieve better performance. That's where I located the antenna on my wifes XJ. Problem is, it doesn't look as cool (to some people)...especially with a big fat antenna like the Firestik. But there are many other antennas out there that would out perform the Firestik product that most certainly are more attractive, IMO.

So if it were me, I'd start with the most simple stuff first one step at a time;
- Extra ground wire from the mount to the chasis (easy)
- RG mini 8 coax for power wire
- Power supply filter (which will be useless if the RFI is coming from the fuel pump)
- Extra ground wire from the chasis of the radio (which I think you've already done)
- Live with the sqelch turned up Sad
- Antenna relocation (last resort)

Sorry to ramble, but there are many things that could be causing this.
Wink
Back to top
View user's profile Send private message
ThePhantum
Pissed-Off Admin
Pissed-Off Admin


Joined: 23 Jan 2004
Location: I knew it...I'm surrounded by Assholes!

PostPosted: Sat Apr 16, 2005 1:55 am    Post subject: Reply with quote

Chris, pretty much what IBTJn said. Except, since the noise you are hearing is directly correltated to engine RPM and since you've got everything else pretty tight (power from the battery, everything grounded well), I would try a noise filter first. It will probably take care of it...at least it did on our Jeeps (TJ & XJ).

On the XJ there are no extra ground wires, but there is a filter. Power comes from an always hot on the fuse box. If I turn the gain all the way up and set my sqelch with the engine off, then start it....there's no ignition noise whatsoever.

On the TJ there is a ground wire from the antenna mount to the chassis and the radio itself is mounted in a Tuffy overhead box, which is tied to the chassis. It's got a filter too....again no noise whatsoever.

I think a filter will set ya straight...if not try using mini-8 as your power cable like IBTJn suggested.
_________________

97 XJ Sport with a bunch of stuff
Quote:
Never argue with idiots, they drag you down to their level and beat you with experience
Back to top
View user's profile Send private message AIM Address Yahoo Messenger MSN Messenger
quadna71
Member


Joined: 02 Jan 2004
Location: Delaware

PostPosted: Sat Apr 16, 2005 5:13 am    Post subject: Reply with quote

i think i'll try the filter first. i took quite some time originally running that power wire (loomed and hidden - straight feed from the battery) to rerun it again. my antenna mount is on my jeeperman tire carrier - and i ran a separate ribbon ground to the frame to ensure that the carrier would be grounded (bearings and whatnot). the chassis of the radio does have the ground wire from it to the firewall - and that is grounded to the frame as well. so - noise filter it is. any recommendations? never had to buy one so not sure if there are different applications or levels of filtering.
thanks everyone,
chris
_________________
2003 TJ Sport
Back to top
View user's profile Send private message Send e-mail
IBTJn
Moderator
Moderator


Joined: 31 Dec 2004
Location: Just Outside of Portland, OR

PostPosted: Sat Apr 16, 2005 7:05 am    Post subject: Reply with quote

thephantum wrote:
Chris, pretty much what IBTJn said. Except, since the noise you are hearing is directly correltated to engine RPM and since you've got everything else pretty tight (power from the battery, everything grounded well), I would try a noise filter first. It will probably take care of it...at least it did on our Jeeps (TJ & XJ).

quadna71 wrote:
"...i took quite some time originally running that power wire (loomed and hidden - straight feed from the battery) to rerun it again."


Yes...I agree and don't blame you a bit. Do the simple stuff first. Especially if it's a PITA to rewire.
Wink
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic     Forum Index -> Electronic All times are GMT - 8 Hours
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Visit links4jeeps.com for write-ups, forums and clubs




Jeep®, Wrangler, Cherokee, Liberty and Grand Cherokee are copyrighted and trademarked to Chrysler LLC.
jeephorizons.com is not in any way associated with or endorsed by the Chrysler LLC.
All other content is copyright Jeep Horizons 2004-2008.
Tech write-ups Links Discussion board Land use News Site Map Terms of Use

Powered by phpBB © 2001, 2005 phpBB Group