Hi,

I have a 2001 911/996 Twin Turbo that is a great car in all ways except fro when I went to put in a small dualband 2m/70cm transceiver for communications. On the frequency area I use the most which is around 146-147 Mhz, their is spurious noise actually pouring out of the engine bay area that registers an S9 level across the band. There are no issues on 400Mhz, just 146-147Mhz. The opposite applies, when I transmit with more than 10 watts in with the antenna anywhere near the back of the car, the engine dies so it sounds like RF is both being produced spuriously by the car computer and then being killed by the RF from the transmitter.

Has anybody had any luck with shielding and extra earthing to fix this problem? Any suggestions are greatly appreciated.

Kind Regards
Brenton
South Australia
Australia

 

I'm no EE, but I know that RF does affect computers adversely, so I can see your 10watt transmitter having an effect on the vehicles ECU. As you may already know power dissipation is on a logarithmic scale so even a few extra feet away will make a gigantic difference. If you mount the antenna in the front under the lid, does it still affect the car, if not, then it is the power level of your transmitter.

 

Possibly using a lead shield around the ECU. I remember back in the day they would sell a x-ray shielding bag for film that you would use to protect it at the airport that I believe was lead. You could find them at a photography store. Lead should shield RF noise.

 

nono, you do not want to insulate the ECU in any way. It gets very hot and with insulation it could shut down due to overheat.

 

Man how much more hot can it get... its allready under 4" of foam,carpet metal and Porsche then located it sandwiched right over the engine compartment. You woulded actually have to bag it just lead shield over it to troubleshoot.......... here is a question.......what are we doing in are TT to be transmitting this bandwith?

 

maybe that is a powerful jammer

 

ok, so exactly where is the ecu on the 996 TT? The transceiver is just a small ham radio we use between my girlfriend and I. If I can locate the ECU, a bit of rf shielding and a few ferrite cores may assist.
kind regards
Brenton

 

Cell Phones have't taken over in Australia yet? The ECU is located on ther rear shelf just under the Bose sub enclosure behind the rear seats given its not a GT2.....no sub or rear seats

 

Thanks for that, I will do some investigating in the morning, I am sure I can work out an answer with some shielding and a few earths here and there. The trick is to move or attenuate the oscillator that is the culprit without altering anything to do with the cars operation. Piece of cake, not haha, anyway, a good learning curve. I will report back any advances made.
regards
Brenton
South Australia

 

can you vary the power output to see where it begins? I'd like to know this so that I can take one of these ham radios to the track and decimate my enemies.

 

A perforated shield will work too it'll cut don the RF penetration a lot.

 

Use a directional antenna...like an EMP pulse!

 

I've not encountered any issues with EMC problems on my TT and I have from time to time installed 'ham gear' running on 144 /430MHz at the 50 watt level.

FYI I installed the antenna on the front lip of the engine cover.

Normally automotive ECU's are designed from the ground up to be largely if not totally immune from these effects - especially if you happen to be driving past a multi mega watt HF transmitter for example.

I'd check the grounding of your antenna.

73 Tim