Fakra connections

[mike ryan]

I have bought an aftermarket radio and luckily I have all the leads needed from a previous purchase but when I come to connect the aerial there are 2 plugs. Which one do I plug the adapter into to get radio reception?

[richard@thebrae]

You will see that one connector is white, and the other beige. Both these connectors are Antenna leads as the most VW's use a system known as diversity which feeds a dual tuner. It works with some circuit trickery inside the radio which senses which antenna has the best signal strength for the station you have selected and switches to it automatically and seamless as you drive about so as you will never notice.
With your aftermarket radio if you only have one antenna feed then it just has a single tuner and the performance in weak signal areas will be very much less than a dual tuner radio.
There is diversity adapters for such occasions, but in my experience they do not perform any where near that of the twin tuner radios (I would give them 8/10 at best). So for where you live either buy an adapter or choose one of the antenna leads which gives you the best reception (FM that is as AM will be very poor). See this as an example :- AN2203 VAG Twin Fakra DIN Diversity Antenna Adaptor | eBay

[mike ryan]

Thanks for the help. I managed to get one from the local car audio for about 3 times the price but the missus has got no patience and wanted it fitting.

One other thing that has perplexed me is i have used a universal can bus adapter so i can easily get the feeds for reverse etc. Now when she switches between modes in her trip computer the frequency on the radio moves up to the next step. It is almost like it thinks the trip computer buttons are steering wheel controls. Any have a clue what might cause this?

[richard@thebrae]

I would say that the universal Can Bus adapter is not Tuned to your car, Ask the supplier if there is a switch option (might be inside) that will tune it to your vehicle or can you exchange it for one that is, or, if it came with the Radio then it might have a hidden menu to alter its behaviour

[TDiBoraSam]

Ok, just to add to this dual tuner puzzle a bit....

I recently fitted an aftermarket unit in my Jetta, originally using a single lead aerial adaptor. The signal was rather poor on all but the strongest stations, with some kind of signal weakening happening when I turned on the ignition.

Another chap on the forum (Jetta section) kindly advised me that a dual lead adaptor might help, so I fitted one, and it's not made the slightest bit of difference, other than I can now get excellent MW reception (not that I ever listen to MW stations).

Another interesting thing is that FM picks up feint interference from the windscreen washer, but MW does not.

It may seem a daft question, but will the AN2203 VW adaptor perform better than other aftermarket adaptors?

[mike ryan]

I dont know how these tuner/fakra adaptors work or what they do really but i feel the issue is not with my aerial adapter as such.

I know that there are some switches within the can unit which may have an effect on the function of the radio. as it had been set up for a golf previously and i dont think that the switches were anything to do with the radio frequency. I will double check them first and will probably be back on here to resolve why it is still doing it.

If it were my car i would put up with it but you know how women are.

Will report back with my findings.

[richard@thebrae]

To try and answer both your question
1) TD BoraSam If you have a beesting antenna and a rear windscreen which gives a dual antenna feed on the oem radio then this is how it works :
The radio has a dual tuner and some sophisticated circuitry that constantly moniters the strength of the signal being recieved for the station you are listening to. as the signal is blocked/ bounced or effected by the orientation of the car it switches to the best signal between two antenna's a) the beesting on the roof which has an amplifier within the base and is powered from the radio up the lead. and b) the antenna in the windscreen which is not amplified but has filters ect. to get rid of unwanted interferance from many things. It does it seamlessly and instantanious without you being aware. Single tuner radios cannot compete on reception performance except in very strong signal areas.
I have never been able to get those diversity adapter's to perform anything like the a twin tuner radio. (the chinese clones now have twin tuners due to the constant feed back and complaints) see Audiosources site or dynavin.

2) Mike Ryan your canbus system is just like a computer network which distributes information and commands around the vehicle on the canbus network the signal sent must be understood by the recipiant and so if you send a signal from your multifunction SW which is interpeted by the universal canbus to ask the radio to change frequency then that will happen , so if the switches are set wrongly in the universal canbus and you send it a command to do something and it sends out the wrong instruction because the switch setting is wrong, then that is where your problem is likely to be.

[TDiBoraSam]

Thanks Richard. I can understand how it works now. What I can't understand is why my car has two aerial leads? I don't have a beesting aerial on the roof, so I am presuming I only have one aerial which is in the rear window? I also can't understand why the signal on the radio weakens when I turn the key in the ignition? If I turn the key back to off, the signal on the radio comes back to full strength when the car's electrics shut down again. Nothing is ever simple hey?!

[richard@thebrae]

I used the beesting antenna as an example as it is the most common intallation. Some vehicles (especially Audi avants/estates) have the side windows also as an antenna. I see you have a jetta, PM me the year and I will look up the layout for you. In respect of your signal decreasing when you power up, Have you tried switching around the antenna connectors on the adapter you have ? Is it a powered adapter ?, could your set up have a bad earth ?
I know it is difficult with after market units on VAG cars and nothing ever seems to perform like the OEM stuff. Audiosources and Dynavin and a VW special from Kenwood seem to be the best. Zenec is just another chinese clone although the sales info would have you believe otherwise.

[TDiBoraSam]

OK, I have an update (success story). I took the radio out again, and messed around with the aerial adaptor, and what seems to work is disconnecting one of the car's aerial leads and just using one of them. It all seems to depend on which of the car's aerial leads you use and which lead you use on the aerial adaptor. I did a bit of trial and error, and I now have both FM and MW working perfectly well, no interference, no loss of signal when the car's electrics are live. As I mentioned in a previous post, I don't have a beesting aerial on the roof, so I have no idea where my aerials are or which one I have ended up connecting, but I'm guessing it's whichever of the two is amplified. The aerial adaptor's blue power wire is connected to the blue accessory wire on the back on my head unit. For info the car is a 57 reg Jetta. Hope this helps anyone with similar radio troubles.