Merc chassied van Radios

I have no doubt this has come up before, but there is a power failure on the site we are on so dont have the chance for searches.

Have any of you with any of the Merc vans had problems with your cab radios/aerials

Its for a forum member who cant get on the internet at the moment

Thanks anyway I understand there is a coax problem when the original aerial is moved. Dont know myself being a Ford Fan

I have had 2 Merc based vans, a Surrey and now a Suffolk and have had no problems with either the radio or the aerial.
Don

My Malvern radio reception was poor on delivery when tuned to my station of choice - BBC Radio 2. Switching off the reversing camera monitor made a slight improvement and installing a Halfords amplified internal aerial made a big improvement but there are still many areas of the UK were that station cannot be received - not a problem in my car or any previous vans.

I've spoken to several other Merc owners who have similar problems but no one has found a guaranteed solution but then none of us have been able to get at the aerial amplifier installation above the roof lining.

Peter

The only problem we have had when using the radio or playing a CD is we occasionally get interference. At first we thought it happenened underneath power lines, but it seems to happen anywhere. So if anyone has any suggestions....

It is important that Coax Cable has good tight screening and often a lower quality cable is used which has loose weave screening.. There 'may' be also an issue over the cabling when the Sprinter aerial is removed to allow fitment of the coachbuilt body. Peter knows more about this than I and he may explain

I wonder if Auto-Sleepers use an aerial extension Lead to move / extend the aerials position? When fitting my sony head unit recently, the wires were a bit tight so I decided to fit one in our Nuevo, but found the radio reception much worse than the standard peugeot unit, so removed the extension lead and it was an instant improvement suggesting to me they do degrade the signal.

Could be mistaken.. bit I'm pretty sure that the newer Merc based Auto-Sleeper models at the Lincoln show seemed to be fitted with wing mounted aerials rather than the usual fitted to the side of fibreglass luton?

CC

CruizingComet wrote:so removed the extension lead and it was an instant improvement suggesting to me they do degrade the signal.

It's true that you can get significant degradation, partly through contact resistance, but mainly where there is a mis-match in the characteristic impedance of the two cables. They are supposed to have a specific value (typically 75 ohms) but cheap extension cables could be way off this. Where the two mismatched cables join, the signal gets reflected back towards the aerial, and hence significant losses - so if you can get away without one the result will almost always be better.

I am aware of several Mercedes conversion radio reception but have heard no concerns over the quality of CD audio. All I can think of is that either their is a loose connection for power or speakers or that the unit itself is faulty.

Before conversion the aerial downlead is cut and the aerial and amplifier removed from the cab. During conversion the aerial is fitted to the conversion roof and the downlead reconnected. On mine I found the reconnection was by solder joints of the inner and screen but in a manner that left some 5" of the inner exposed. There is a 12v power lead (operated by the radio on button) that folows the coax into the roof but no sign of an earth or return connection. There is no DC path between the radio end aerial connector and the aerial. I conclude that there is an amplifier installed at the aerial but it has no DC return path. I believe the exposed inner was actually the 'aerial'. Unfortunatly it was right next to the power supply for the rear view monitor and also picked up substantial interference from that. Rather that remove lockers and roof lining to get at the aerial/amplifier, I installed an internal dipole with integrated amplifier. This has minimised interference from the monitor and improved reception but it is far from perfect.

I have seen a friends downlead connection. That is connecterised but the connectors are up behind a locker and there is no slack to bring them down for examination. His radio reception is appalling all the time and I expect his amplifier is not powered and that he is not benefiting from 'exposed inner' as an aerial.

A couple of people have changed radios with no improvement and one has a thought that the Sargent power interface unit causes interference but that is not the case with my van.

It does seem that most Mercedes owners are not aware of a problem so it may be that just occasionally a power wire is not connected or it may have become disconnected up in the roof.

pcb7ty wrote:I am aware of several Mercedes conversion radio reception but have heard no concerns over the quality of CD audio. All I can think of is that either their is a loose connection for power or speakers or that the unit itself is faulty.

Thanks, pcb7ty, for the reply, but even when a CD is playing the amplifier picks up interference. The quality of the audio is not the problem.
The radio/CD unit picks up interference quite possibly from a dodgy aerial extension allowing extraneous signals in, as would appear to be the case in other vehicles.

Time for an update.

Last year I bought a new Tomtom sat nav and found that it was also being interfered with by the 'always on' reversing camera/monitor installation so I had a switch fitted in the power feed to the camera system so that it could be switched off completely.  When off there is no problem with the sat nav or the radio (still on its Halfords internal aerial).

I am aware of another Mercedes owner who has had the camera power supply re-located and that eliminated the interference problem (but not the drop out fault that he is more concerned about) so that inspired me to experiment.

I reconnected the original Mercedes aerial and measured the current in the power feed to confirm the aerial amplifier was working.  As expected the performance was better than with the internal aerial.  The interference on weak stations is still bad and switching the monitor off with the remote control only reduces it slightly however switching the whole system off eliminates the interference completely.

At last (after 2 1/2 years I'm certain that the problem is the fact that the camera system is electrically very noisy and that mounting it above the cab internal light is a bad place to fit it.  I did have a thought that the connection to the camera that runs in the roof might be taking the interference to the proximity of the aerial but disconnecting the camera at the power supply end makes no difference

Having got used to doing it I'm happy to continue to switch the whole system off when not needed for reversing (the switch is in the dash adjacent to the gear lever).

Peter