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Old 03-28-2010, 07:00 PM   #1
speedy77
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Default FM reception sucks after install of Kenwood DNX5140

Finally got my total sweep done !!....One thing I haven't been able to get right is the FM reception. It's not even close to the Blose unit.
I have the blue wire on the GMCO / B3 hooked to the power antenna wire from HU (I also had tried the wire for the amp power up...the same). It does get better when I attach the power wire but still poor. I checked the bigger antenna wire seems OK.
Does the ground wires have anything to do with it ? I just have all the blk. wires hooked together but didn't run them to ground. Everthing else works fine on the HU.
Is there an FM setting in the Kenwood 5140 ? I looked through the manual 100 times..nothing.
Thanks
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Old 03-28-2010, 08:07 PM   #2
markcz
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Originally Posted by speedy77 View Post
It does get better when I attach the power wire but still poor.
Click the image to open in full size. If you have the module powered with 12v, that's about all you can do. Plastic cars make for bad antennas
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Old 03-28-2010, 09:19 PM   #3
Darion
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I didn't have great reception with the Kenwood I had, but then again my Alpine is really no better.

I had the factory setup in for such a short time I don't know if it was good or not?

Darion

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Old 03-29-2010, 11:22 AM   #4
Blackout
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Originally Posted by markcz View Post
Click the image to open in full size. If you have the module powered with 12v, that's about all you can do. Plastic cars make for bad antennas
I only know of the C5 but if the C6 is setup in a similar manner with 2 antenas (one front windshield, one back rear deck both going to a power module) then you have to power up the module with the proper voltage. Markcz has been giving me great information! He is one smart dude on here.

Markcz/OP...do you have the module grounded? You mentioned all the black wires "tied together" but not grounded?

Last edited by Blackout; 03-29-2010 at 11:25 AM.
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Old 03-29-2010, 06:43 PM   #5
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In C6 there are 2 antenna modules, both located inside the rear bumper, and both have their own ground, so all you need to connect is the +12v. There is a 'FM Composite Signal' wire that normally connects to the stock radio, but nobody ever confirmed exactly what it does. I believe it's some kind of feedback type system that would tell the modules if the signal is good or bad, telling them if they need more or less amplification, but that's just speculation.

Click here for the antenna schematic.
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Old 03-29-2010, 08:27 PM   #6
WB6HRO
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The composite FM signal is most likely the sum of the two antennas, less prone to fading.

It is also known as Diversity Antenna System using more than one antenna.

Sometimes they polarize one antenna vertical and one horizontal.

The intent is to fill in areas that may flutter due to signal strenth.
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Old 04-03-2010, 08:50 AM   #7
crease-guard
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Quote:
Originally Posted by WB6HRO View Post
The composite FM signal is most likely the sum of the two antennas, less prone to fading.

It is also known as Diversity Antenna System using more than one antenna.

Sometimes they polarize one antenna vertical and one horizontal.

The intent is to fill in areas that may flutter due to signal strenth.
This is correct. The service manuals spell out how this system works. Unfortunately, any aftermarket system won't give the FM composite signal. Our only solution would be to buy an aftermarket antenna or replicate the composite signal circuitry and algorithm used to fine tune the signal.

Jay
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Old 04-05-2010, 12:22 AM   #8
Jimmy 2 Times
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i put a metra glass mount antenna under the grill (where the center speaker is) and that greatly improved the signal.
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Old 04-05-2010, 12:22 AM
 
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