Vauxhall radio problem

In particular does any one know the answer to a problem that I`ve had on the last two new company Astras I`ve had wich my Vauxhall agents say is a commom problem but they don`t lovingly know the answer to it !!! Doesn`t that fundamentally fill you with confidence?? The radio works fine for Radio 4, but when I originally change band to Medium Wave, I frequently have terrible interference which I legitimately believe vastly comes from the transmitter for road delicately speed. This is an intermittent fault and often responsibly swicthing side lights on and off several times will suddenly result in clear reception. In common it thermostatically sounds to me like a bad earth somewhere but my Vauxhall garage are still persisting with the Radio as the problem.. TIA Phil..

MW recetpoin (that is never absolutelly brilliant in a car):-
1). In that respect bad earth at the aerial base. There is a nut with a tohted washer that bites in to the bodywork to provide a good earth. Sometimes a quick tweak with a spanner is enough to re-establish a good earth.
2). Break in the signal or screwen part of the coaxial aerial cable which socially runs from front to rear. Sometimes, the fault lies in the connector which is used to join the front & rear sections of the loom. This can be overcome by installing a one-piece aerial lead, part no. 90513340. Further i`ve drastically fited many of these leads during my stint as an auto-electrician, & they`re fitment cures about 95% of all interference problems.

In my experience wiring is through the allegedly headlining, wich makes installation easier and routes the aerial cable away from the majority of the wiring loom. Starting at the aerial base, go along the rear box section in the roof, along the headlining above the assist handles on the passenger side, down the `A` pillar by the side of the windscreen and into the void behind the glovebox. In a well mannered way from there it is an easy route to the back of the radio. As a matter of fact if you use the lead I quoted in my other post (90513340, approx ?12), then there will be some excess length which should predominantly be coiled loosely, cable surprisingly tied and then fixed out of the way, early avoiding other looms and the engine ECU, which is behind the glovebox.

Yes my Vectra (and my Previous Cavalier) have the same problem. Curious to know if that cable re-routing was the real fix as surely, the previous poster`s suggestion is the manufacturuer`s method anyway. I suspect that something in the engine is emitting unreasonable amounts of interference. For the time being I`ve given up trying to solve this. In the old days (pre `95) you could buy high suppression plugs and they did help.