My FM reception is poor and fades in and out as I drive from block to block. I live in the SF Bay Area and I do not encounter this problem with my other car radios so it is not the strength of the radio broadcasts.

Has anyone else encountered this problem?

 

Some vehicles have antenna boosters. Not sure about the SL600.

 

Posted the following before but my 2003 SL500 has relatively poor sensitivity on AM but reasonable on FM. My 1989 560SL had a better quality Am FROM A Becker radio in my humble opinion. In a city like SF you should have sterling FM quality.

 

Radio reception is very poor in my SL. I live in the east bay and if I head into the hills, forget it. The good news is we have CD players. Since I have an SL55 I can also just enjoy the engine sound.

 

and by poor, I mean the worst of any car I have ever driven.

 

No reception issues with my 04 SL500

 

me neither. actually pretty good! 04 500SL

 

Mine sucks too but I live on the edge of existance, other vehicles are fine, just the SL has problems. Doesn't bother me though, I just put hook up my phone and turn on Pandora, no problems.....

 

My own opinion is, that in general, newer auto radios are only marginally better than those from a decade ago. In the headlong rush to hide antennas for fashions sake they have gotten shorter and less efficient and the radio front ends (NF) have not kept up in performance to cancel that degradation. Almost all my old Becker radios were more sensitive than my current 2003 SL 500 radio, of course they all had outside antennas. I don't even know is the current supplier to MB for radios. The AM performance suffers the most because it requires the longest antenna.

 

These cars I recently discovered have a complicated antenna switching/amplifying system that uses feedback from the COMAND unit. My reception was OK with factory COMAND unit, but now my FM reception is bad, especially higher frequencies. (I installed a Pioneer AVIC 140, two new amps, and steering wheel interface to use the volume and up/down buttons). I believe the new head is only getting the AM antenna signals cleanly . A local installer claims these new radios have bad tuner circuitry, that factory radios are better and that's why, but I don't believe Pioneer is putting out a $1,000 radio that has lousy FM performance. I do realize that the HD radio signals require higher levels, but even the analog FM stations are weak at best, and essentially unusable where there are a lot of hills and valleys.

There are actually four windshield antennas with two FM amplifiers (right and left) and two AM antennas, one in the rear window and the other the rear shelf for when the top is down, with it's own amplifier. The left FM amplifier selects and amplifies one of the four antennas based on its processing of an IF signal feedback from COMAND depending on the interference in the IF signal.

If you have factory COMAND unit then you may have a bad amplifier somewhere in there (don't ask me how to diagnose). I'm in San Diego and my 2003 SL55 had pretty good FM with the factory unit.

 

Thanks for the technical update. Insane complexity for a marginal enhancement of performance. As I mentioned previously the reception on my SL500 2003 is acceptable but inferior (AM) to previous Beckers. CD and using my Blackberry as a MP3 player through the aux port is fine.

 

I am wondering if you can bypass all that and run your antenna cable directly to the amplifier or antenna network.

 

There are two amplifiers for the windshield antennas, located under the dash just below each A pillar cover. The amplifiers are part of an antenna diversity system that is powered and controlled through the factory Command system, so if you go with an aftermarket head unit the amplifiers go dead and in fact serve as a barrier to direct connection with the actual antennas. Even if you figure out how to power up these amplifiers, I'm not sure how you'd integrate them into an aftermarket system.

For my system, I bypassed the amplifiers and connected directly to the windshield antennas, including an aftermarket antenna amplifier. It works, but the reception is still not great. FM stations switch between HD and standard mode constantly, with an audible shift in sound quality. It's annoying. I'm next going to try connecting a flexible/wire antenna , keeping it hidden under the dash.

I think it comes down to the fact that windshield embedded antennas just are not nearly as good as traditional aerials. GM did a lot of windshield antennas back in the 70s and 80s and they were never good. I think all the complexity of the R230 antenna system was not to get objectively superlative reception, it was just to get decent reception comparative to most cars without adding an aerial to the exterior of the car.