Randy V

I've had crappy FM and no AM reception since I got this car. It has a nice Pioneer/JVC/Boston Acoustics setup, but the radio reception has been lacking. The antenna connection is properly plugged into the head unit.

How can I test what's not working in the signal reception/antenna setup?

It looks like the twist-off mast on the roof installation may have a break inside it - it seems too 'bendy'.

Can I test the mast section for continuity to determine if that's the problem?

Thanks for any guidance.

Airflite40

the gts has the fuba antenna on the rear roof? if so, those antennas are amplified and have a 12v connection attaching to the base of the antenna in addition to the antenna signal cable. sounds like the antenna is not getting the 12v to aplify the signal.

SharkSkin

Randy, if it's a coax connection you could try that, see if the reading changes as you flex the antenna. IIRC FM is 75-300 ohms, but that's impedance. Don't worry so much about what the number ought to be; what's important is that it's not open circuit. Another thing you could try is straighten a coathanger and touch it to the antenna mast connection. If your reception improves then the antenna wire up to that point is probably fine.

ROG100

Randy,
Where the antenna plugs into the back of the head unit there is a small wire attached to the antenna wire (green and brown IIRC). That should be attached to a 12v feed which comes of the plug that goes into the stock radio.
Because it is aftermarket someone may have not attached it. Thats what feeds the 12v to the amp up near the mast.
Roger

GT Jackson

No Am and poor Fm is a def signal that the antenna lead is kaput. As above, check the 12V power to the antenna booster through the lead to the antenna, or a Rube Goldberg boost via coat hanger, etc. Even holding the antenna lead in your hand should ad a boost to the signal. Check also that the booster has ground to the chassey via the antenna, without ground, the entire system is crippled as the auto body also assists as a receiver.

jon928se

"Borrow" an antenna from a Golf (aka Rabbit?) or a Toyota Rav 4 ( I know those fit )

Or try the coathanger.

If no difference then check for 12V to the antenna base out of the head unit, if yes check at the base of the antenna for 12V feed.

Amplified antennas with no power don't recieve anything like as good as a non-amplified antenna.

If all that makes no difference remove antenna co-ax from head unit and replace with a single piece of wire about 4 feet long - if better the co-ax is knackered.

borland

Antenna tester ...

http://cgi.ebay.com/Seco-CB-SWR-Ante...QQcmdZViewItem

borland

Like what was suggested, check the antenna for 12V power by removing the sunroof motor cover. There's a electrical connector there.

It could also be a bad match between the receiver and the antenna.

The internal amp on my 1990 S4's rooftop antenna was bad. After replacing it, my reception is good here on the fringe of L.A. That's with a Blaupunkt Orlando aftermarket unit.

928Intl sells an after market antenna, but they could not tell me if it was a direct replacement. So I ordered the part from Porsche.

See my prior post about using a shower faucet wrench to remove/replace the antenna base.

imfinlay

I had the same, and got a NOS antenna off ebay. It helped noticeably. When I removed the original antenna the base was corroded. Looked fine on the car though... The signal connector can be a point of intermittent failure also.

I got a NOS cable with mine, which I didn't use. PM me if you need one.

Ian

Randy V

Thanks for the info, guys.

I failed to mention that the 12V source is hooked up to the antenna.

I'll give the coathanger trick a try.

Any specifics on how to test for 12V at the antenna base?

heinrich

Randy, I like to pull it all the way down to the roof with my finger and let it go. if it makes a "PHLUPPP" sound, it's time for a new antenna. But if it makes a bold "VERRRRR" .. well then .. your antenna has schwing

Seriously, the only antenna a 928 needs is a coil of antenna wire under the passenger footwell carpet.

heinrich

Another thing Randy ... I have had different head units with very different results. One had almost no AM, and swapping in a different radio I suddenly have perfect AM.

Randy V

Tell me more. I've tried hooking up a small flex antenna direct to the head unit but reception was not good. Most antenna installations require contact with body ground to work properly.

heinrich

Well, Shane has perfect reception and we discovered he has a coiled piece of antenna coax about 3 feet long under the passenger's carpet. No issues.

Bill51sdr

Randy, have you replaced the roof antenna yet? If not yours may have a bad amplifier and you have to replace the entire unit. I have a known good mast if that turns out to be the problem and you need it.