Z3 - comically bad FM reception

[mccalli]

OK, so...improvement. ish. Kinda. Sorta.

Took the radio out again and tried pushing in the aerial harder as suggested. Connector didn't quite seem to click, so I took it out again and it came apart into two pieces. Hadn't considered this previously but it's obvious now I do - the original aerial ends in a DIN connector, but the aftermarket head units want ISO. So this barrel is a DIN->ISO adapter. Faffing with it (by which I mean just unplugging and plugging in a few times) produced a better connection.

Success! Or so I thought. Driving away in east London I could get signal. Autoseek still found nothing, but if I hand went to the frequencies then a few were clear enough to get RDS info - Radio 4 for instance. I thought it was sorted, but as I drove on the signal got more and more crackly until at some point round the M25, somewhere near St Albans, it just became too crackly to hear what was being said and it got worse from there. Never recovered to the point it could get RDS info again, for instance.


So I'm back to my original state - comically bad reception, as opposed to the zero reception that happened when the whole lot just crumbled and needed replacing.

 

[mccalli]

Oh, I should add a possible reason why my DAB reception is awful too. Halfords have installed it, and it's just clicked that it's been installed horizontally. DAB aerials are polarised I believe - pretty sure it should be installed vertically. Not sure I'll get that chance though as the film ones aren't reusable I believe, so I think it's going back to Halfords with me saying oi - fix please.

 

[Redline]

Oh, I should add a possible reason why my DAB reception is awful too. Halfords have installed it, and it's just clicked that it's been installed horizontally. DAB aerials are polarised I believe - pretty sure it should be installed vertically. Not sure I'll get that chance though as the film ones aren't reusable I believe, so I think it's going back to Halfords with me saying oi - fix please.

DAB Antennas should be vertical in cars. A part of the antenna will always be vertical irrespective of which direction your car is pointing to pick up the vertically polarised signals.
Many cars have multiple dab antennas behind bumpers.

 

[mccalli]

My FM thing is sounding more and more like posts I've seen on generically bad reception in German cars. Such things as this for instance, or this showing a full install (1:44 for powered antenna explanation). I've checked it out and my wiring does look correct to my (totally non-expert) eyes, but the symptoms are exactly as described.

I've seen recommendations to use one of these, but if I follow my wiring back I can see that the the blue/white wire on the ISO head unit wiring loom goes to a blue wire marked "antenna remote" on the ISO car adapter. The car adapter goes into the original BMW wiring, and that blue 'antenna remote' ends up connecting to a white wire on the originals, which goes to pin 16 - powered antenna.

I think that's all correct. Blue/white is for remote (meaning 12v supplied to a remote accessory when the ignition is turned on) and is connect to the blue 'antenna remote', which in turn is connecting to the white 'power antenna' of the original.

So it looks right to me. Just feels like it might be the same problem. At this point I'm actually quite interested in getting hold of an original BMW Business Radio and plug it all in without the harnesses involved, see if has same issue. That way I'll know whether it's the aftermarket wiring harness configuration or not. E36 ones are silly prices on eBay, but E46 ones which seem to have similar wiring - those seem reasonable.

 

[hard top]

My FM thing is sounding more and more like posts I've seen on generically bad reception in German cars.

Absolute rubbish, had quite a few Mercs & BMW's over the years, upgraded the head units, no problems.

 

[mccalli]

Absolute rubbish, had quite a few Mercs & BMW's over the years, upgraded the head units, no problems.

No - I meant the lack of knowledge about wiring up power antennas, which are typically associated with German cars. Happened on my 996 too, and it's all about the power antenna mostly.

 

[mccalli]

So - DAB reception appears fixed, FM is spotty but a little better. And the fix?

First off, DAB aerial was re-oriented vertically. Seemed a little better, then zero reception and massive drop-outs. Zero on the FM again too. Fitted a powered aerial adapter (even though don't think I need one) to the FM - maybe better, maybe not. Hard to say, still poor.

But the DAB, which is an entirely separate antenna? Fixed by removing the USB 12v socket charger. Astonishing difference. With the charger in (and actually charging something), I get close to zero FM and I get bad DAB with very frequent drop-outs. Charger out? Much better, though still crackly, FM and DAB has zero drop-outs in the areas I've tried it so far.

Hmm. So the charger isn't properly EMI shielded then. Hard to find info about the EMI shielding on these adapters online. Am also considering doing something like this instead - an in-dash hard-wired solution. I mean, that says it's for a particular truck model but it's clearly just a 12v accessory wire-powered adapter, so if the dimensions match the blanking plate on the switches I have (near the traction control and the electric window) then it should work. Says nothing about EMI there either, but you'd hope something designed for in-dash would be better.