| Author |
Message |
    
Boxcar
Intermediate Member
Username: Boxcar
Post Number: 357
Registered: 4-2002
| | Posted on Monday, January 02, 2006 - 9:31 pm: | 
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I have a question here. I am trying to install my cobra 29 ltd classic into my truck along with a messenger 350 and am having what appears to be a hum when I key up the amp. Not sure if this is a ground problem so I will try to explain how I am trying to troubleshoot this. I hooked up both positive and negative wires from the amp straight to the battery posts. The radio I had in a cigarette lighter outlet so I thought maybe there was a short somewhere or ground problem so I hooked up the pos. and neg. wires from the radio straight to the battery also and it still hummed when I keyed the amp. Doesn't hum without the amp so I'm stuck. I replaced the pl259 connector on the antenna and still have the same issues. I am using a wilson 1000 antenna so I'm not sure if there is an issue with the antenna. It does appear that it gets worse when the dynamike is turned higher though. Is there anything that I might have missed? I did have this issue in the past with another cobra radio and amp that I used but it didn't do it this bad. I do have a section of 10 guage wire that I soldered to the wires on the amp that are a little bigger but I don't think that is anything to worry about since it's not that high of an amp. Any thoughts? |
Wildrat
Advanced Member
Username: Wildrat
Post Number: 581
Registered: 12-2003
| | Posted on Monday, January 02, 2006 - 10:53 pm: |
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Did you adjust the SWR?
Did you install equipment grounds? |
Kid_vicious
Advanced Member
Username: Kid_vicious
Post Number: 973
Registered: 9-2004
| | Posted on Monday, January 02, 2006 - 11:23 pm: |
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your ground wire from the amp might be too long.
try running a big wire (8ga. or heavier) from the amp to a big bolt like a seat bolt or something, and keep the wire less than a foot long. |
Road_warrior
Senior Member
Username: Road_warrior
Post Number: 1116
Registered: 7-2004
| | Posted on Monday, January 02, 2006 - 11:28 pm: |
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Do what Wildrat says:
Get SWRs as low as possible. And ground.
Make sure your jumpers and connectors are
good. Coax and connectors are good. Sometimes magnet mounts cause problems such as this.
Or antenna and mount are not properly grounded
to vehicle.... Good Luck!
JIM/PA/CEF 375
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