Passat aerial amplifier poor reception problem

[charliecwmboy]

Hi to all,

I' have a problem with the radio reception on my B5 passat 1999, the same as alot of people, I receive only the strongest FM signals and no am/lw signals.

I know there is an amplifier built into the antenna base, so i measured the voltage coming out of the centre pin on the head unit.

On start up the voltage on the inner pin goes to 12vdc, after about 3seconds the 12vdc switches off. I thought, ok it's waiting for a current to be seen, if it doesn't see the current it removes the voltage....perhaps an open circuit on the antenna base amplifier.

So my first thoughts was that it was the amplifier base.....

I changed the mast to a shark fin amplified one off ebay, changed that out yesterday - even worse reception.

Then I found this http://personalpages.tds.net/~luvail/v919911.pdf

A technical bulletin from VW about checking the set up of the radio.
If you don't want to look at the link:

"Service
Checking antenna connections, electrically
through radio

–

Switch radio ON.

–

Press and hold balance button for approx.

ten seconds.

♦

3CPT7 will appear in display (numbers may

vary and are not important)

–

Press CD mode button.

♦

020.I will appear in display (software version

numbers may vary)

–

Press CD mode button again.

♦

FERN OFF / ON will appear in display
Note:
FERN = amplified antenna.

If FERN ON appears:

Antenna and connections are OK.
If FERN OFF appears:
Radio may not be coded correctly for
amplified antenna.
–

Check for proper coding of radio, see coding

table in Technical Bulletin Group 91 number

99–09 dated Oct. 25, 1999.
♦

When radio is coded according to this table

FERN is operational.

If radio is coded correctly and FERN OFF
appears, then antenna and connections are
not OK.

– Check antenna and connections ⇒ page 3"

On my radio, the FERN is saying AUS, which I'm taking as translated to "out of play" or off?
My questions to you guys are,
1. Does FERN go on and off with good / bad connections on the antenna circuit or does it need to be forced "on" with something like Vagcom ?
2. How can the radio be correctly coded for an amplified antenna ?

Doubtless there are quite a few people going through the same thing out there - changing bases and aerials, still getting the same poor reception problem and it could be that the FERN setting has gone to off which means the voltage is not getting to the mast.

regards
charliecwmboy

[snapdragon]

Mine is crap too, I bought a new patten aerial base off ebay it was worse, new proper VW aerial and back to just crap . I changed the mast too, still crap . The radio was coded for Amplified antenna in VAGCOM and it is just as crap whether I code it on or off . I think the problem is the cable between the aerial and the head unit and I'm not going to mess about pulling carpets and trim up . To be honest, I'm no longer bothered after two years of avoiding radio I have got used to it. Sorry if the emoticons offended any muslims!

[Jon Eagland]

I have a similar issue but my problem is caused by an intermittent short in the cable/connector in the headlining just beneath the aerial unit. The radio appears to stop trying to power the amplifier after 5-10secs if the current drawn is to high.

When it goes wrong I can fiddle with the cable and it comes good for a few weeks/months. Replacing the cable would be difficult and very messy - carpets up trim removed etc.