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Does anyone here know about radio reception?

Pretty simple. I'm looking for better radio reception, primarily FM between 90 and 100 MHz. I'm having issues with interference (a 12V USB charger is particularly bad, but power-lines too) and I think poor aerials.

Is it earthing? Shielding? Do I need to filter power feeds?
I'm using a mid-range pioneer MP3 bluetooth head-unit. But issues were the same with the last head-unit.
 

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I know a little about radio reception. There can be multiple factors in play. Some you might fix and some you cannot. One issue can be the presence of a very strong station nearby. Can be very bad if you live in a valley because the transmitter of that station blankets the valley and tends to block out other stations. We have a town near where I live that has that issue. People there have a hard time getting any stations except the one in their town. Another issue can be the makeup of the ground where you live. Certain types of soil or rocks can have negative effects on radio signals. Hard to fix that if it occurs. There are signal boosters on the market. Haven't been involved in that for over 20 years so I don't know what might be available. Engine created noise coming through the power line can usually be controlled with a filter. Airborne noise is far more difficult. Some type of shielding material on the engine compartment can help. There are probably materials out there now that absorb airborne radio noise. Like I said, it's been a long time since I was involved in the car stereo business. Are there any specialty shops in your area that deal car stereo?
 

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I know a little about radio reception. There can be multiple factors in play. Some you might fix and some you cannot. One issue can be the presence of a very strong station nearby. Can be very bad if you live in a valley because the transmitter of that station blankets the valley and tends to block out other stations. We have a town near where I live that has that issue. People there have a hard time getting any stations except the one in their town. Another issue can be the makeup of the ground where you live. Certain types of soil or rocks can have negative effects on radio signals. Hard to fix that if it occurs. There are signal boosters on the market. Haven't been involved in that for over 20 years so I don't know what might be available. Engine created noise coming through the power line can usually be controlled with a filter. Airborne noise is far more difficult. Some type of shielding material on the engine compartment can help. There are probably materials out there now that absorb airborne radio noise. Like I said, it's been a long time since I was involved in the car stereo business. Are there any specialty shops in your area that deal car stereo?
This is the only vehicle I've got with terrible reception, the rest of them are fine. I think it's a combo of crappy aerial and electrical interference that I'm dealing with.

No specialty shops in my area. The inbuilt antennae in most modern vehicles seem to be way better than the old-school whip type I'm trying. I've got two new aerials, both terrible. Both shielded cable from head-unit to the body mount.
 

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Actually, nothing wrong with the old whip type antenna. Do you know what the length of the antenna is? Seems like the one on my old Ford truck is around 1 meter. I used to do a lot with CB radio and there were all kids of antennas for those. Is this vehicle gas or diesel. Gas engines often present more noise issues than diesels.
 

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The formula for calculating a quarter wavelength receiving/transmitting metallic element's length based on frequency is as easy as 2-3-4. For 95MHZ it is 234 divided by 95 [the frequency in MHZ] which gives 2.4631579 feet [or US 29.5578936 inches]. This converts over to 75.077052792 centimeters in length.

The most efficient mounting location is the rear center location on a SUV roof 75 CM forward from the rear edge [the gutter drainage portion]. If another antenna is located in this area the FM antenna should be at least 75 CM in distance from the original antenna.
 

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Good info Bob. My current antenna is probably in the 29-30" range. Never had a reason to measure it. Don't listen to radio much any more. I have a super high end unit in my stereo system in the house that I haven't turned on in years. By high end I mean it even has ultra pure silver wire in the internal circuits and 3 tuning meters on the front where you can zero in on the frequency. The company had one model better than mine but $5000 for a FM radio seemed a bit much. LOL.
 

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Dougal,

Got a long shot, from the days I drove old IH trucks with gas engines. For electrical noise originating from the engine, ground the hood (bonnet?). I ran a 10 gauge wire from a bolt on the hood hinge to a nearby, under hood, ground point. p.s. #10 wire was for strength, not current carrying capacity.

Question: Does the audio frequency of the noise vary with the engine RPM? If so, ignition noise (gas engine) or alternator are the first suspects.

Swap the 12 Volt USB charger into a different vehicle, does the noise follow. Substitute a known good USB charger from a different vehicle.

I suspect that you will need some sort of filter, my knowledge in this area is too obsolete to make a recommendation.
 

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Thanks for the info Bob. I had seen this stuff before years ago but lost it all. I have two whip aerials. One long which gets better reception but is at risk from garage doors etc. The other is shorter, of wire wound type under rubber coating and not working well at all.

Dougal,

Got a long shot, from the days I drove old IH trucks with gas engines. For electrical noise originating from the engine, ground the hood (bonnet?). I ran a 10 gauge wire from a bolt on the hood hinge to a nearby, under hood, ground point. p.s. #10 wire was for strength, not current carrying capacity.

Question: Does the audio frequency of the noise vary with the engine RPM? If so, ignition noise (gas engine) or alternator are the first suspects.

Swap the 12 Volt USB charger into a different vehicle, does the noise follow. Substitute a known good USB charger from a different vehicle.

I suspect that you will need some sort of filter, my knowledge in this area is too obsolete to make a recommendation.
The electrical interference I have is from cabin electrics (wiper motors, USB power adapters for phone chargers etc). I can start and stop it just by turning stuff on/off and unplugging. Doesn't scale or react to motor/alternator noise.

I had reasonable success putting a small capacitor across the terminals of the wiper motor 10 years ago. But I am wondering if there's something in my setup that's making this worse. The Aerial cable is new, shielded and a lot longer than it needs to be (approx 1.5m bundled up because 0.5m would be enough). So that is bundled up.

There may be an earthing issue with the aerial mount. I will check that. The scuttle panel it is mounted to is aluminium and it's mounted on plastic washers I think for corrosion protection. The result being some form of electrical isolation/insulation. Hmmmm!
 

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When you say "bundled up" is it coiled by chance?
That would be bad. Try randomly scrounching instead. Also, do not pull any zip-ties tight. If you're indenting the coax it is too tight. Same for tight bends, if the coax is kinked it is too tight of a bend.

Car stereo competitors put a honkin BIG cap across the power leads to any of their system, but primarily the amps. Partly that is for the big bass hits, but it also acts to filter out noise in the vehicle's power system.

The battery itself is a pretty good filter. Ham radio operators usually wire their radios direct to the battery, both power and ground.
 
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