Fm radio reception

Themoog2 · Post by **Themoog2** » Sun Dec 08, 2024 9:52 pm

Here is a strange one.. All of the fm radio stations that are stored in the head unit are clear and interference free apart from Radio 2, 88-91mhz. I only listen to it as it has no adverts. Honest.
Why would just that frequency be so poor? Is it anything to do with the box in the top of the tailgate.. And when I switch on the rear de mister it wipes out the signal anyway.
I had the bm54 unit tested a while ago and that is OK apparently. The reason for that was when the weather gets colder the radio goes all quiet with no bass and just sounds dreadful. I thought it may be dodgy solder joints in it but it's not.

X5Sport · Post by **X5Sport** » Mon Dec 09, 2024 6:09 pm

How long has it been happening? There should be suppressors to prevent the demister circuit having any effect. It might also be a weak signal from the local transmitter. If engineering works are underway and it’s recent then the transmitter power is turned down (cooking engineers tends to cause too much paperwork!)

Radio 2 is broadcast between 88.1 and 90.2MHz. Local broadcasts for the area are on 88.9MHz (Madingley @ 11.6kW) and 90.1MHz (Peterborough @ 208kW - the local main Tx).

I’ve found FM to be quite poor in this part of England even with an aerial in the roof at home. DAB is fine, but FM not so good as coverage from Peterborough is a bit weak. Madingley is ‘invisible’ here. E53 doesn’t have DAB of course!

Themoog2 · Post by **Themoog2** » Mon Dec 09, 2024 6:24 pm

It’s been about 6 months. Maybe it is a rubbish signal.. oddly, a video popped up on YouTube and the guy unplugged the bm54 unit by the battery and cleaned all the contacts. Maybe it’s that? It’s just strange that it’s only Radio 2 that’s affected.

X5Sport · Post by **X5Sport** » Mon Dec 09, 2024 7:44 pm

I would expect all stations to suffer if the radio was u/s, hence wondering about the suppression circuit. Peterborough Tx for R2 is running at 40kW these days but I can’t find anything better than that. I used to have access to all the transmitter data and engineering reports but no more sadly. There are two ‘wave traps’ used in the E53 to stop problems between the demister and radio. One is at upper left in the tailgate:

: IMG_3135.jpeg (75.74 KiB) Viewed 6884 times

The other is the opposite side:

: IMG_3136.jpeg (83.1 KiB) Viewed 6884 times

Out of interest, does the signal improve even with the demister if you drive to the top of a hill? Yes I know Cambridgeshire is vertically challenged

Themoog2 · Post by **Themoog2** » Tue Dec 10, 2024 4:32 pm

I'll try I tomorrow as I do happen to have to go over a hill.

Themoog2 · Post by **Themoog2** » Wed Dec 11, 2024 7:54 am

OK. Did the hill test - the de mister didn't affect the signal at the top of the hill although it was still dodgy.

X5Sport · Post by **X5Sport** » Wed Dec 11, 2024 5:29 pm

So it’s signal related. Have you tried the other local broadcast frequency? You haven’t said which you’re tuned to, though if I remember correctly the receiver should auto tune when a weak signal can be improved via a better (higher strength) broadcast of the same station.

If only Radio 2 is affected then it sounds to me that the aerial system itself is fine. Radio 2 broadcast signal just isn’t good enough in your area, and that can be caused by engineering works such as replacing either the transmitter, aerial feeds or masthead unit.

X5Sport · Post by **X5Sport** » Wed Dec 11, 2024 5:36 pm

You could have DAB retrofitted? If you’re interested then Cartronics may be able to help. No idea on price though.

Themoog2 · Post by **Themoog2** » Wed Dec 11, 2024 8:59 pm

I’ve often thought about a new head unit that is digital with android but it has to look like the original. And not cost £400..

Themoog2 · Post by **Themoog2** » Wed Dec 18, 2024 11:56 am

I removed the tailgate trim at the top and this is what I found.

Themoog2 · Post by **Themoog2** » Wed Dec 18, 2024 11:57 am

There is an antenna connection that was taped to the frame - it looked like factory fabric tape so maybe it’s been there forever..

X5Sport · Post by **X5Sport** » Wed Dec 18, 2024 2:58 pm

The unit is the aerial amplifier module. 433.92MHz is also for the central locking. E53s were made with a single loom (unlike all later models) so maybe the ‘spare’ was for one of the cellular options. Possibly for the US satellite based radio Sirius(?).

Did plugging the errant cable back in fix the issue though?

Themoog2 · Post by **Themoog2** » Wed Dec 18, 2024 3:58 pm

I didn’t plug the errant cable into anything. It didn’t fit anywhere.
I did unplug the antenna cable from the box and back in again- and further along there is a connection that I did the same. I haven’t tried it yet.

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