| Author |
Message |
    
Jose22
| | Posted on Monday, September 02, 2002 - 8:00 pm: | 
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I have a Kenworth tractor, and have a Cobra 29 with a Palomar 250 amp. The amp creates a buzz when turned on. SWR on antenna is less than 1.5 on a K40 4' antenna (Mirror Mounted). The only way to get the buzz out is to turn mike gain way down. But when I do that the modulation is too low to be hear loudly enough. With amp off everything is clear and can turn mike gain up for clear and loud. Buzz is so bad that no audio can be heard. Radio is mounded in cab top panel and amp is under dash in glovebox. Have 9' jumper from radio to amp. Have tried other lengths but no help. CAN THE AMP GURUS PLEASE SPEAK UP. Thanks a lot. All help greatly appreciated. |
Tech671
| | Posted on Monday, September 02, 2002 - 9:40 pm: |
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The radio carrier needs to be 1-1.5w, is it? Is the final coax from the amp to the antenna good? Are you supplying the amp with 10ga wire to a direct battery sorce for hot and ground? Is your antenna bracket grounded to the frame direct with 8ga or larger wire?
Check these things and see if you still have the problem. |
Tech808
| | Posted on Tuesday, September 03, 2002 - 12:27 am: |
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Jose22,
On our 2000 Kenworth L800 I had to go direct to batteries to avoid this. If you are hooked to Stock wireing from Kenworth on top of dash you will feed back through the wiring for radio. I assume your CB mount is on top of Dash. Even with going direct to batteries with my 2970DX 10 Gauge Wire) I still set off turn signals when I keyed mic. I ran a set of twin Monkey Made (Short Shaft) antennas on it mounted to mirrors and Braided copper grounding wire run to frame. I also had to mount External speaker right behind my head behind Drivers Door to avoid Feedback.
Hope this will give you some help!
Lon
tech808 |
Jose22
| | Posted on Tuesday, September 03, 2002 - 8:47 pm: |
|
Thanks guys, Here goes.
Coax is ok.
Radio output 3 watts.
10ga wire used to supply amp.
Kenworth stock hookup on radio.
Ran amp directly from battery. (even tested using jumper cables).
Antenna mounted on mirror. No ground wire. Would this create a problem, ie resonate since over 30". Ground could be several feet long to get to frame.
Advice on ground ie how to run and type of wire and I will try this weekend.
Thanks guy. I really do appreciate it. |
Tech808
| | Posted on Tuesday, September 03, 2002 - 9:05 pm: |
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Jose22,
On my KW-L800 I ran 14 gauge Plastic speaker wire with an eyelet soldered on end mounted to Mirror Antenna brackets bolt.
Thru the hole in Mirror brackets where Heated mirror wires ran, down thru door then thru floor where I drilled a 14" hole to run my power wires for radio to batteries. Then Drilled and ran Stainless Steel self tapping screws into frame.
Hope this helps!
Lon
tech808 |
Tech808
| | Posted on Tuesday, September 03, 2002 - 9:09 pm: |
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Jose22,
OOPS! 1/4 inch hole not 14 inch hole.
Bet, I hear it on this mistake, Typing to fast!
COME ON TAZ let me have it!
Lon
tech808 |
Tech671
| | Posted on Tuesday, September 03, 2002 - 9:50 pm: |
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This may sound like overkill, but I installed a XForce X400 in a KW a few months ago and grounded the mirror assembly with # 6 wire direct to frame. We didn't have any problems. |
Jose22
| | Posted on Wednesday, September 04, 2002 - 8:50 pm: |
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Thanks guys, will try this weekend. |
Capncrunch
| | Posted on Thursday, September 05, 2002 - 7:58 am: |
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maybe you should try a differant amp ive had amps hooked without a ground that never made a buzz and same with ungrounded antennaes just might be something wrong with the amp have you tried it in another vehicle? |
Capncrunch
| | Posted on Thursday, September 05, 2002 - 8:02 am: |
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jose what kind of kw is that you have and is this the factory coax to your antennae cause that also might be the problem with some of these newer trucks having the same coax run the cb and am fm stereo which is just trash |
Jose22
| | Posted on Thursday, September 05, 2002 - 5:34 pm: |
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CC, coax is good quality mini 8. Trashed the factory stuff first thing. Tried another amp, similar stuff. Will do suggestions this weekend, will let you guys know.
Thanks for the input. You guy are RF STUDS. |
