Crackling radio

I have a non landy radio/cd in the disco 1 ( a cheap'n cheerfull bit of kit) but the radio reception is awful. The cd player is crystal clear but when the engine is running the radio sounds like your listening to it in a bag of crisps and it gets worse when your actually driving along.
This is the second radio I have tried in it, the first one that was in the vehicle when i got it had the same problem, so I've changed the aerial as well and fitted a window mounted antennae with a built in booster but its made no difference.
Its definately electrical interference as it gets worse when I operate the lecky windows but I cant figure out why it happening. the radio is plugged into the original socket which, as far as I can see, hasn't been modified or interfered with. None of the loom wires that feed the radio plug are damaged or chaffed, the aerial lead is new, I have cleaned all the electrical grounding points, and now I'm stuck for ideas.
I could fit an in line suppressor but I'd rather find the cause and cure it.
I have done a search for any threads on similar probs but could only find one to rewire around the original amp in a Jap spec disco which didn't help me.
Is there a suppressor somewhere on the disco that could have failed?
Its driving me nuts so any help would be great.
Ta.

Tune it in

Needs a suppressor on the alternator terminals.
Also try running a wire direct from your battery for the supply wire and use a ground as close as possible.

Muddygamekeeper said:

Tune it in

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I thought they were tuned in at the factory before they got sold

Is it as bad on FM as it is MW? Maybe the built in alternator supressor has died? Check for good continuity between the bonnet and the rest of the bodywork. Does the interference stop if you are in gear, driving along and take your foot on the accelerator? If it does it'll be the diesel injectors and that's a bugger to clear up!

Put a suppressor on the ignition coil.

discool said:

Put a suppressor on the ignition coil.

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Errrrrrrrrrrrrrrr - it's a TDi according to his profile?

thebiglad said:

Errrrrrrrrrrrrrrr - it's a TDi according to his profile?

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I don't bother to look a profiles, if OPs can't be bothered to give the info on they vehicle etc etc in their posts, I will assume they have a petrol-engine vehicle

discool said:

I don't bother to look a profiles, if OPs can't be bothered to give the info on they vehicle etc etc in their posts, I will assume they have a petrol-engine vehicle

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You truly are a knob !:rofl:

AceB said:

Is it as bad on FM as it is MW? Maybe the built in alternator supressor has died? Check for good continuity between the bonnet and the rest of the bodywork. Does the interference stop if you are in gear, driving along and take your foot on the accelerator? If it does it'll be the diesel injectors and that's a bugger to clear up!

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MW and FM both about the same.In gear or out, moving or stationary, makes no odds, its just a constant poor reception once the engine is running, though if I operate the windows with the ignition on but the engine off the motors interfere with reception (as do the wipers.)
If I run a temp clean feed from the battery this weekend and see if that makes any odds then Ill use the exsisting acc.live to the radio to operate a switched relay for a direct to battery connection.

Most head units are suppressed for 'ground noise' such as window motors interfering with reception plus wiper motors etc, perhaps your "a cheap'n cheerfull bit of kit" is not, or if it was they are not working now. Perhaps u could try a portable radio in the cab and see what interference u get.
All this assumes that the head unit and antenna are installed correctly.

the radio that was fitted when I bought it (not original equipment but a relatively good quality head unit) had the same problem, which is why I swapped it out so having two units with the same problem pretty much rules out an issue with the unit itself. The original stereo plug that comes out of the loom has been used to connect both, and the wiring hasnt been tampered with as far as I can see. The new aerial and booster came with a new antenna co-ax so the aerial is not likely to be the culprit, so I'm pretty convinced that its electrical interference from the cars 12v system in the live circuit.

Is the aerial wing mounted or in the o/s rear window along with its signal amplifier positioned above the head lining? also a coax cable in close proximity to a power cable can pick up interference and should have the screen grounded at one end.

Re-using the existing head unit connection sockets won't give u a problem but ensure that the unit is connected directly to earth also the power cable has a suppression choke fitted at the head unit .

Try powering the head unit from a seperate 12V supply, it will determine if the noise is coming up the power line or being radiated and picked up by the aerial. Have you powered the aerial amplifier?

TBH I'd be surprised if any car radio, no matter how cheap requires an amplifier on the aerial. Most just increase the noise along with the wanted signals, the S/N ratio remains the same or even gets worse.

discool said:

Is the aerial wing mounted or in the o/s rear window along with its signal amplifier positioned above the head lining? also a coax cable in close proximity to a power cable can pick up interference and should have the screen grounded at one end.

Re-using the existing head unit connection sockets won't give u a problem but ensure that the unit is connected directly to earth also the power cable has a suppression choke fitted at the head unit .

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The original aerial is wing mounted, but the new aerial is an internal electronic booster aerial which is mounted inside the windscreen behind the drivers side sun visor. The power and coax run behind the drivers side windscreen pillar trim, and its earthed with its own clean terminal to the pillar itself. The coax and live for the aerial are in proximity to each other but I would imagine the current is minimal. Besides which, the original coax from the wing aerial was nowhere near any live cables and it had exactly the same problem

TBH I'd be surprised if any car radio, no matter how cheap requires an amplifier on the aerial. Most just increase the noise along with the wanted signals, the S/N ratio remains the same or even gets worse.[/quote]

I dont think the radio needs the booster as such, it just happened to be an easy to fit internal glass mounted antenna which I thought would be a reasonable alternative to try and eliminate the original aerial as the fault.