Ignition interference

[Mike E (uk)]

I know this is a tricky one, but has anyone had success in suppressing radio ignition interference on a petrol BX?

Fitted the CB ready for the BXagon, but the ignition noise is drowning out all but the strongest signals.

I don't suppose the plastic bonnet helps here, but it does have the mesh fitted.

thanks,

Mike

[prm]

Mike, this takes me back a few years!!!

Couple of things you could try, but not sure how this would adapt to your BX set-up.
Have you got coil, points, distributor or EFI???

A condenser/suppressor attached to the coil feed wire may help.

Going back quite a few years, 30 !!, they produced an inline suppressor for the distributor to coil lead.

If you can ?? Temporarily remove the alternator belt, to determine whether the main interference is electrical or ignition.

Regards

[mountainmanUK]

IIRC (from my CB days of 1981 ) my old GS had to have an inline suppressor in the dizzy-coil lead, together with anti-interference plug caps (aren't they all now?).
It was also usually necessary to fit another suppressor to the alternator. This was more of a "whine" which varied with engine speed, rather than a 'ticking' which came from the ignition.

Some helpful stuff in this article........
http://www.quest4.org/radio/reducing_no ... erence.htm

REMEMBER!!! Messing with an electronic ignition system can cause serious damage!!!

[DLM]

Apologies for sticking my oar in on someone else's behalf, on a topic I know next to nothing about.. shoot me down gladly.

Have you got coil, points, distributor or EFI???

As it's a 16v, isn't it EFI by default?

American site 1992 vintage, but some diags & suggestions http://www.cbtricks.com/members/kd6tas/cbfaq4.htm in the 'mobile' section, or go looking on any UK farming forums? Connection direct to battery, suppressor in that direct feed circuit seem important.

[mountainmanUK]

Connection direct to battery, suppressor in that direct feed circuit seem important.

That would make a lot of sense, as it would not involve ant direct tinkering with the original Cit wiring nightmare!!

My own CB memories are VERY sketchy these days, as I was on the original AM (illegal) system back in 80/81. Went off when they legalised everything on the FM system (if Ive got it the right way round?).
I remember having a magmount DX twig on the back of my 76 GS, which was Jaune Citron, and earned me my CB "handle"....Banana Split!!!!
Happy Days!!!

[mike st gilles]

I must say that I don't know a great deal about these things.....just seem to remember having a particularly 'noisy'(crackly,engine sparky) radio that I fitted myself and just didn't know what to do with it. After putting all types of suppressors and other suchlike things, a neighbour from down the road (turned out to be an auto electrician) came over and said that 'they all do that mate' .....'and this is what we sort it out with'....he called it a 'choke'........which was fitted on the power lead inline between fusebox and the radio ......maybe it was a suppressor but it certainly worked on the interference in the power lead.
Hope it helps...

[Mike E (uk)]

The subject of CB in the 70s/80s is worthy of a new post.

When I first got involved in CB it was 1979 and I was too young to drive, so ignition interference was not a problem.

Yes CB was really cool when it was on AM and illegal- that just added to the cult nature of it.

Worst thing that happened was making it legal, so it became a craze and it all got too crowded and folk lost interest in it.

Many CB operators moved on to amateur radio, including me, and ignition noise is much less of a problem on VHF.

I am reluctant to modify the ignition system of my BX (1992 16V) but the noise is definately spark related because it speeds up with engine rpm.

I have checked the HT system thoughly, and I have no significant interference problem on the normal car radio (VHF of course)

I will ground the CB case to the car chassis next.

There is some arcing of the HT leads visible in the dark, which is likely to be the source of the noise, but I have not yet found a way of stopping this.
Is a certain amount of arcing normal perhaps?

Thanks for any help,

Mike

[Jaba]

Mike - two thoughts:

1. You, perhaps, are picking up interference via the aerial. This can be minimised by moving its location.

2. Where are you picking up power from. If its in the engine bay and the leads(s) are anywhere near the ignition components then they might be picking up RF. My hands free phone picked up bad interference until I moved the professional installation engineer's fused power connections from the battery to inside the cabin where they were shielded from the ignition RF.

I used this philosophy to cure a.m. interference on the radio as well.

Hope this helps good buddy.

[citronut]

i know this will not help your prob, but when the BX first came out, i worked for a a citroen service agent (H G HAVAUX) on the A21 just outside of Hastings,

the BX used to suffer from the digy clock going scatty, we had a tech bulitin sent which said to fit a suppressor to a wire under the bonnet, cant remember for sure which wire it was,

citroen supplied the part and part No.
which even though it had a differant part No. we discoverd it was actualy a GS ignition condensor

regards malcolm

[Mike E (uk)]

I will power the CB from a nicad pack, and see if that helps.

That will show if the noise is fed by the power leads or radiated.
(I suspect it is being picked up by the aerial, which is on the roof near the boot hatch)

Power leads go direct to the battery currently.

I will also walk around the car with a hand held radio and see if I can detect the noise source.

thanks for the ideas,

Mike