I have a 98 CLK with the radio antenna embedded in the rear windshield. My reception of distant stations is fine, but I have problems with the stereo decoding on FM. It seems to drift in and out of stereo when driving the car. The dealer checked the antenna and the connections are OK. He swapped out the radio control unit for another one but the difference was marginal, so he put the original one back in. At this point, he says the problem is probably the design of the rear window antenna and there is nothing else he can do.

Has anyone else had problems with this window antenna design? Has anyone replaced it with a conventional radio antenna or perhaps the rubber one that comes with the Cabrio? How about a signal booster? I'd would be happy to hear your experiences/suggestions.

Do you live in a large city?
Are you near the transmitter site?
Do you live in a hilly area?
The problem may be “multipath”
That is a when the original signal arrives at the car antenna closely followed by a strong reflected signal. The two signals
interact as you described. There is no cure for this unless you go to an exotic diversity type ant. System in the car.


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1999 E-300TD

Richard,

It is definitely reception related because it's worse in my neighborhood. However, I drove my other car with a regular fender antenna (an old Toyota) down the same street with the same station and the stereo locks in perfectly. My Benz keeps switching from Stereo to Mono (although the Radio indicator always reads 'stereo'). That's why I concluded it had to be that rear-window antenna setup. Now I would like to figure out some way to improve it without destroying the look of the car. I don't want to drill any holes in the fender until I am certain it will solve the problem. I wonder if anyone else had problems with this antenna design.

Try adding a signal amplifier, they are cheap and it is worth to try...

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WEB Site : http://www.adamou.dpn.ch
A.S.C. 1999
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Is the signal amp easy to install? Are the connections standard..or is there a special Benz connector?

I'm willing to try if it's not too difficult.

It is easy to install. It's a small box, needs a +12V, put it right behind the radio if there is place... You just have to connect the antenna cable to the box and the box to the radio and it is done. The signal amplifier shouldn't cost more than 15$.

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WEB Site : http://www.adamou.dpn.ch
A.S.C. 1999
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I'm not sure if the signal amp will help much; the signal coming in is hampered by the window antenna, the antenna elements likely are only a few cm from the rear defogger wires. In a big metropolitan area, signals may well overload the head unit's tuner section. FM is tricky to get right, and the factory antenna may well be inadequate for your particular neighborhood. Drilled antennas work the best, in my opinion. Perhaps you can put the cabrio's antenna in the same location it is on the cabrio? I can understand if you are reluctant to make a new hole in a 98 CLK, though.

I thought the late model MBs that have in glass antennas came with an antenna amp installed. I have a 00 ML320 and a 00 E320 and both have terrible reception. Short of drilling holes and running a "real" antenna, I've been told there is no solution. Since I've replaced the head units in both cars with aftermarket ones, with only slight improvement, I'm convinced it's the design.

My wife just bought a BMW with the same rear antenna setup and her radio plays fine. I convinced Benz to swap out my head unit again with another one. We'll see if this helps.

Maybe your antenna cable is broken somewhere... Who knows...

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WEB Site : http://www.adamou.dpn.ch
A.S.C. 1999
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Well...it's finally fixed. The dealer replaced the head unit (this is the 2nd one we tried) and it finally works. I'm a little disappointed that the replacement is 'reconditioned'. I expected it would be new, but since it took two tries to get a good one, I'll stick with it.

By the way, I learned that there IS a signal amp in the car. It's somewhere in the right rear panel between the right rear window and the rear windshield.