When I listen to Medium Wave, which I tend to do a lot, I am getting a huge amount of interference from the car stereo. Sounds like static but is vaguely related to engine speed and is loud and thorough enough to totally cover the station itself.
What with the CD changer, Sat Nav, Phone kit and everything else, I had just resigned myself to not really being able to listen to MW anymore.
But here's the weird bit, which I daresay has always been the case but I only noticed today - when you push in the cigarette lighter to heat it up, *all* the interference stops and MW is clear as a bell; although as soon as the lighter pops out the interference immed. returns.
There is no interference on anything else, including FM.
Any bright ideas ? ("bright" excludes any smart comments about using the lighter more or leaving it pushed in).
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Is this on your Toyota?
I believe that alot of German cars (mine included) have very bad MW reception as they do not have (m)any stations on MW - not sure if Japan is the same. I believe that the MW ariel is grouped together with all the electrics and this causes the poor reception.
Having said that the ciggie lighter is curious and I will try that out next time I'm in the car! Have you tried plugging in a phone charger when you are driving (rather than keeping on pressing the ciggie lighter)?
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I tried the phone charger, it didn't work.
And yes, this is the Toyota.
As you say, it is the lighter which makes it curious - because when that is pressed in the reception is perfect.
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It sounds as if whatever they have for a voltage regulator nowadays may be at the bottom of it; does any other high current device - eg headlights - have the same effect? If so you can always pretend to have a Volvo when you want MW.
A dubious contact at a connector may have curious results, and can be cured by disconnecting and reconnecting a couple of time; but the trouble is there are so many, and in odd places.
Must see if Toad has this effect. Shall go and see.
Tomo
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Bit of a long shot - check to see the radio body is well earthed. Try introducing a temporary good one.
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>>Try introducing a temporary good one.
'scuse the ignorance, but how ?
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>>Try introducing a temporary good one. 'scuse the ignorance, but how ?
I think Frostbite is suggesting you attach a nice chunky wire from the chassis of the vehicle to the chassis of the radio.
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>> >>Try introducing a temporary good one. >> >> 'scuse the ignorance, but how ? I think Frostbite is suggesting you attach a nice chunky wire from the chassis of the vehicle to the chassis of the radio.
Perfectly put! Thanks DD
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Odder and odder. Toad gets MW interference when, and only when, the lighter is pushed in; but only a momentary effect when switching on headlamps.
Something odd about Toyota and lighters?
Tomo
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>>does any other high current device - eg headlights - have the same effect?
Not as far as I can tell, and I've just been out there fiddling. Its got some $%#$ big lights on it, and 240v outlets; neither using them nor not has any effect one way or the other.
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Sounds like you need to call the lads at Oxford Car Audio again Mark.
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Can\'t Dave, he\'s got chickenpox.
Anyway I feel a bit of a prune keep asking them dumb questions.
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So lighter provides easier path for interference to flow down. Suggest you provide filtered power supply to radio. Can afford to loose a volt or two as running car up to 15V. Medium wave weaker signal so also could be mismatch on aerial lead, aerial poorly earthed, or interence current preferring to go down aerial screen rather than bodywork.
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So lighter provides easier path for interference to flow down.
But why would the interference take that route when there must be a thousand easier routes to earth ? Also, doesn't a lighter rely on rather high resistance to warm up ?
>>Suggest you provide filtered power supply to radio. Can afford
>>to loose a volt or two as running car up to 15V.
Is this as simple as buying a filter (what would I ask for) and wiring it on the power lead like an in-line fuse ?
Medium wave weaker signal so also could be mismatch on aerial lead, aerial poorly earthed or interence current preferring to go down aerial screen rather than bodywork.
And what would I do about those, or is it "ask an expert" time ?
And even if the signal is weaker, if I tune in to an FM station that I can barely receive, then even though the reception may be terrible, it doesn't seem to have the interference.
Thanks so far.
M.
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If the radio and the lighter share a common earth wire, (and the earth is electrically 'dirty'), the effect of reducing interference when a high current load is taken from the lighter is not that surprising.
The suggestion of trying a clean earth directly from the radio to car body is a good idea, but make sure if it is permanently fitted that it is capable of taking the maximum fused current of the power feed to lighter/radio and whatever. (The reason for this, is if the old earth from the radio comes away from the chassis earth connection, all current will then flow down new wire. Lighters sometimes take 15A (I think), a thin wire would then start to heat up with possible nasty consequences!)
A Haynes manual may show if they share common earth.
pmh (was peter)
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Talking about strange intereferences, when i change into neutral I often get a strange noise coming from MW.
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I've recently found that I can improve the sound quality of my local FM station by turning the heated rear window off.....probably a bad electrical path somewhere as one of the strips on the window doesn't work.
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OK we won’t go into who listens to MW any more but as you do let me explain. This problem is often caused by the aerial being part of the rear screen heater thus a poor MW signal as the Heater element design is optimised for the 88 to 108 megahertz band (FM). However the real problem is the design of modern front end receivers. To cope with all the different conditions AGC (Automatic Gain Control ) is used at the front end of the receiver this RF gain is effected by both the expected received signal and the noise associated to engine/ignition interference, management system emissions, windscreen wiper motors and other passing vehicles. Now if everything is connected properly, your bonnet has an earth strap across the hinges, assuming your bonnet is not fibre glass, and the aerial is correctly grounded then just driving along your radio establishes a gain level based on the strength of the MW signal and the inherent noise. However there is a second AGC which is associated with the demodulated audio ( the bit you want to hear ) If you now introduce more noise, say a passing motorbike ignition noise, your radio responds by reducing the RF gain thus slightly quietening the radio thus suppressing the noise you hear whilst the Audio gain tries to maintain the level you hear.
Now that the noise has past the RF gain creeps up so the noise/interference increases whilst the Audio gain falls to maintain the level thus you perceive more interference. If you tune your radio off station then the noise is dreadful because the RF AGC increases in an attempt to find a carrier frequency i.e. a station and the Audio gain increases because it cannot detect an average audio level.
In some set ups even the pressing of the brake i.e. the lights coming on causes interference on MW that causes the RF gain to drop thus effectively decreasing the noise but almost maintaining the audio level i.e. the music bit you hear. The gain then slowly returns to the normal level. The same radio in a different car will behave differently due to the wiring harnesses. During on different loads i.e. head light, heater fans, even the interior light can effect MW reception due to changing the impedance of the supply and alternator loading.
I’m afraid your problem is very common and with the lack of aerial matching, there even used to be a adjustment you made when you fitted the radio or changed the aerial. You could try a filtered power supply, being fed directly from the battery, aerial pre-amplifiers and all sorts of suppression and de-coupling but you may not get much real improvement. FM ( Frequency Modulation ) does not suffer from this as the interference only causes amplitude modulation and this is discarded in the receiver as FM only uses the rate of change of the frequency and the amount of frequency change. The Simple test, try a domestic portable radio in the car running off its internal batteries. Is it any better. Come back and let us know ! Regards Peter
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Thanks Peter, I have a portable radio and I'll try this tonight.
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I've been told the lack of MW reception on the Skoda is a VW group thing, and that the remedy would be to get an amplified aerial. But I'd be very surprised if your Toyota doesn't already have one of those, it seems to have just about everything else! There are a couple of things I can try on the Skoda now, having read this thread. Just got to wait 'til it comes back from the bodyshop, boo hoo...
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It does have an amplified aerial. Pity really, since if it didn't I could fit one.
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Another 'long shot' thought.... I wonder whether aerial deficiency is the problem, and using the lighter (on the same fuse circuit?) provides it with a temporary extra aerial?
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I've just cured most of the interference on AM (Medium Wave) on my Mondeo.
The aerial plug was hanging out and not making propper contact. Pushing it back in has improved things considerably. I've never seen an aerial plug like this one. They used to be very positive and virtually imposible for one to fall out. However, the one they seem to use now doesn't really have any means of retention; it almost needs a strip of gaffer-tape across it to hold it in. Progress in the car manufacturing industry? I'm all for it ??!!
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One quick and dirty test to check the state of the antenna (I can never spell aerial) is to switch the radio on; stand outside the car and grab the antenna. If the reception suddenly improves then there is a good chance the antenna is not grounded properly.
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What's the current status?
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Fiddled with it last night.........
1) touching the aerial has no effect one way or the other.
2) the portable radio on MW seems to work quite well in the car, although there is some interference, you can listen to it.
3) Haven't had a chance to do anything about an earth wire to the radio body yet.
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