Hi Pasty007
You don't say if your van has a roof aerial above the windscreen or some other setup like the ones hidden in the wing mirror for motorhomes.
The wing mirror factory setup uses a small booster amplifier which is interposed between the aerial and radio. It needs DC power, which it gets from the radio via Pin A5 and a separate single wire (ground is via the aerial cable). If the DC power to the booster is lost for any reason, the reception will be a bit worse on FM (you may not even notice) but a lot worse on Medium Wave (AM). So check if you have any disturbed wiring.
A similar thing that can happen is that an aerial connector somewhere isn't properly pushed home. If there is a small gap, the FM signal can to some extent "jump across" the small electrical capacitance of the gap and you'll still get some reception. The much lower frequencies of Medium Wave/AM will suffer a severe loss.
Your nearest Radio 5 transmitter is on 909 kHz and is a mile or two Southeast of Redruth, so the signal should be pretty good.
Bear in mind that when a car radio scans for stations, it is set up to only stop on ones which are reasonably strong. If you tune the set manually, you may find additional weaker stations.
