Defender (Puma) radio interference

Hi All,
Thank you to all who sent comments (and tried to help). Bushies reference to another article was a good start. Since I have had the vehicle I have bonded the exhaust pipe in three places over its length, Bonded the rear door and bonnet .... to no effect. The alternator has not been in the mud! When I go over the vehicle with a hand held radio (as wrinklearthur suggests) ..... with the ignition key turned on (but the engine not started) I get lots of noise. I am not sure if the injectors are firing at this point? (anyone advise on this). The noise is just as bad at the back of the vehicle as at the front .... maybe the fuel pump is making noise?. Someone on another thread suggested the noise could be carried to the rear of the vehicle via the wiring to the lights, demisters etc.
I looked for the fuel pump thinking that may be the culprit .... maybe it is in the fuel tank? ... in which case it will be difficult to put a ferrite on the wires (anyone got a circuit diagram of this bit of the wiring?) When I start the engine there is more noise .... and when travelling along the road the noise changes with throttle setting .... maybe still the fuel pump?
What I cannot understand is a manufacturer making a vehicle that emits so much noise ... to the point where the AM radio (fitted at the factory) is nearly unuseable. I have had a few other diesels ... non were anywhere near as bad as the Land Rover PUMA Defender. (Holden Rodeo ... no noise) (Mercedes ML ... no noise) ... the same HF radios were installed in those vehicles and there was no problem. ... those manufacturers obviously have technical people who are on top of their game. Why Land Rover UK do not want to help owners reduce the interference is difficult to understand. They claim that their military versions are "quiet" but are unwilling to give any clues on how they did it.
Please keep your ideas coming ... they are gratefully received.

Well, as you can see in that link, there are other vehicles with your problem. And don't feel too bad - there was someone who wrote an article for the VKS-737 newsletter about how in their car (I've forgotten the make) the engine would just stop when they hit the HF transmit button! Apparently this was quite exciting on the highway.

They had to go to a specialist who added some bits and the owner didn't know exactly what they were, but they worked. Which just goes to show.

Electronic vehicles are what we're stuck with. I wouldn't mind at all, but a problem like yours just shows how badly designed they are when there's no thought given to things like this. This is why I've stuck with non-computerised Land-Rovers.

Since this is a common a problem, just keep looking at what others are doing. Remember the point is to be methodical and to take one step at a time, much as with any other troubleshooting. Go by the articles that others have written and try and isolate one system at a time, or you'll just get confused.

Just looking at the photo of your antenna mount that you posted on my antenna thread, (thanks, by the way) - how have you grounded it, given that it's sitting out there behind the spare wheel?

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Originally Posted by patto1

When I go over the vehicle with a hand held radio (as wrinklearthur suggests) ..... with the ignition key turned on (but the engine not started) I get lots of noise. I am not sure if the injectors are firing at this point? (anyone advise on this). The noise is just as bad at the back of the vehicle as at the front .... maybe the fuel pump is making noise?. Someone on another thread suggested the noise could be carried to the rear of the vehicle via the wiring to the lights, demisters etc.
I looked for the fuel pump thinking that may be the culprit .... maybe it is in the fuel tank? ... in which case it will be difficult to put a ferrite on the wires (anyone got a circuit diagram of this bit of the wiring?) When I start the engine there is more noise .... and when travelling along the road the noise changes with throttle setting .... maybe still the fuel pump?

Please keep your ideas coming ... they are gratefully received.

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Hi Patto

I'm pleased you tried that search with the AM radio, as you have now found, the vehicle wiring does radiate the radio frequency interference, so do that test with your AM radio again, the same as you did before, with the switch on and without the motor running. Only this time, pull out one fuse at a time out of the fuse box, do your test then after replacing that fuse, move to the next fuse. Without power the device that was making the noise would be quiet, take note of any change in the noise from your pocket AM radio and write down your results then let us know what you have found.

As I said in the previous post, don't try and add so called fixes haphazardly, You can chase your tail forever doing this, it's best to find the source / sources of the noise, before adding noise suppression.

So Patto, battle on and I will keep a eye on this thread to see what develops.
.

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Originally Posted by Davo

Just looking at the photo of your antenna mount that you posted on my antenna thread, (thanks, by the way) - how have you grounded it, given that it's sitting out there behind the spare wheel?

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Hi Davo

Can you put up your link to your antenna thread on here, please ?
I wouldn't mind having a read of that.
Personally, I don't have a licence to use vks-737 at the present, but do intend to get the appropriate permission soon, I have had my Amateur radio licence ( vk7kba ) since about 1976.
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Here it is, from right next door in this section.

http://www.aulro.com/afvb/communicat...ck-rangie.html

Like I was saying on this thread, it's really hard to get a simple answer with this radio stuff, as most of it shoots straight off into ham territory. I tried looking for a picture of how a mobile HF antenna radiates, for instance, and wound up with all these highly technical diagrams! Whew!

Thanks Wrinklearthur .... when I get a bit of spare time I will try your suggestion

thanks

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And something else I read the other day said that braided copper is best for grounding body panels And it sounds like ideally you need one of these straps for every door and the bonnet of a vehicle?




better use bi-metal luggs

Yes, I've read the same thing over the years. It sounds like something you can do one panel at a time to try and reduce the noise, though I've read of people just doing this as a matter of course. I'd be inclined to just go ahead and do it so I know at least it's done.