P38A Radio Mystery...

Fitted a new microphone to my head unit (sony) other week. Now heres the weird bit - whenever i drive i get a beeping interference in the radio (like morse code - yes i have now disconnected the microphone to check - still present) that increases with speed. It is not present when veh stationary. Anyone want to hazard a guess to how speed is affecting the speakers?

Thanks

Petrol? Unsuppressed feed from something in the HT system?

Happened soon as soon as plugged radio back in. wouldnt get through the bulkhead into the back of the radio I don't think !

It's haunted by the ghost of the Roadrunner !!!

Is it a 'beep' or a 'click' and is the noise directly related to engine speed?

If it is a 'click' and it is related to engine speed it sounds like HT 'pick up' but if the sound is more like a 'tone/beep' then it could be a 'logic derived' pulse, (but still related to the engine speed - such as the tacho feed - although I do not know where this is obtained from without looking at RAVE).

The obvious question will be that of 'was the noise there previously, (before you installed your microphone), and if it wasn't, (and you have now put the Head Unit back as it was previously), you could have disturbed some of the audio cables so that they are now alongside your tacho feed cable - just a thought?

Otherwise check the usual 'earths' to the Head Unit just in case you have disturbed one and lost some RF shielding.

I only have the 'standard' unit in mine and I took everything out, (when I stripped her down), and mine is still working fine with no discernible 'noise', (and I wasn't overly careful in the placement of the associated cables), but I have yet to road test her!

Tacho gets it's signal from the CPS via the ECM and BECM. Unless he is getting 4 pulses per engine revolution it won't be that. Just out of interest why do you need a mike on your radio, are you into in car karaoke?

Because the head unit has the facility for mobile phone bluetooth communication would be a logical guess as a microphone is a requirement.

discool said:

Because the head unit has the facility for mobile phone bluetooth communication would be a logical guess as a microphone is a requirement.

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For those really important calls that just can't wait. Oh i see.

wammers said:

For those really important calls that just can't wait. Oh i see.

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It's a taxi Tony

Apologies for my late reply, turns out i was overactive with plugging my amp back in after testing, phone line went in. With the antenna for that sitting next to feed giving me my interference! Ha, making those important calls while driving...was getting tired of hearing "sorry can you say that again" "your line is bad"!