problem with car radio in a steel boat

[ashanta]

I have a car CD/radio fitted onboard a steel boat and I can only get one station. (It's local BBC Notts)
I like to listen to radio 5 on medium wave but I cannot get the station (any station on MW). My car is parked 10 feet away and is OK and my portable is OK if I stand outside on the pontoon.
I have used the fitted aerial system installed with the radio when the boat was built last year and I get nothing but a harsh noise which doesn't change tone as I try to tune. I have also bought a car aerial and fitted that directly to the radio with coax going and aerial going outside. I can get the radio 5 but the sound is masked by a noise.
Is this something to do with earthing? I received the better reception with the car aerial when I touched the fitting bolt to metal outside. I remeber many years ago fitting a radio that had a wire which was fastened to a steel bolt inside the car?
This radio was fitted by an electrical engineer who says "it just a poor reception in the marina" and the sales guy just say's "it's because its a steel boat" I just don't accept these answers but sadly I do not have any answers of my own.
Can any one help?

 

[chamac]

Most MW radios have a hole in the case with a tuning screw on the circuit board. You tune in a weak station and turn the tuning screw till you peak the signal. It tunes the radio to the aerial.

 

[tobble]

you can get a splitter which you connect to your VHF ariel which then filters the signal into two appropriate bands, one for the VHF and one broadcast radio, dunno if that might help. I guess the ariel at the top of the mast could improve things...

 

[DavidTav]

Car radios work perfectly well in the majority of cars which are also made from steel. Car aeriels are external and earthed to the car body. If you try a similiar approach with the boat I wouldn't have thought you would have a problem.

 

[ashanta]

[ QUOTE ]
Car radios work perfectly well in the majority of cars which are also made from steel. Car aeriels are external and earthed to the car body. If you try a similiar approach with the boat I wouldn't have thought you would have a problem.

[/ QUOTE ]

This is the area that I feel the problem lies. I have improved the signal (MW) by earthing the aerial to steel on the outside of the boat but there is still this background masking noise and I was wondering if the casing which fits in a nice wooden unit should be connected to the steel body?
Please keep you ideas coming as they are very helpful. Thanks.

 

[claudio]

The steel hull should not be a return path for the 12V electrical system. You may find that you accelerate galvanic corrosion by connecting the radio case or the aerial earth to the steel hull.
Is the case connected to the negative of the 12 supply line ?

 

[DavidTav]

The advice from Claudio sounds good. I agree that it is probably not a good idea to earth the aerial. I did have another thought on this, why not try one of those car aeriels that don't have to be earthed and stick on the windscreen?

 

[ashanta]

[ QUOTE ]
The steel hull should not be a return path for the 12V electrical system. You may find that you accelerate galvanic corrosion by connecting the radio case or the aerial earth to the steel hull.
Is the case connected to the negative of the 12 supply line ?

[/ QUOTE ]

Simple answer is I dont know so I will investigate this. many thanks

 

[ashanta]

[ QUOTE ]
The advice from Claudio sounds good. I agree that it is probably not a good idea to earth the aerial. I did have another thought on this, why not try one of those car aeriels that don't have to be earthed and stick on the windscreen?

[/ QUOTE ]

Thanks for the response. The in question boat is a Narrow boat so I don't have a screen. It's much simpler with Ashanta in Devon!!

Thanks everyone for your help

 

[ShipsWoofy]

[ QUOTE ]
you can get a splitter which you connect to your VHF ariel which then filters the signal into two appropriate bands, one for the VHF and one broadcast radio, dunno if that might help. I guess the ariel at the top of the mast could improve things...

[/ QUOTE ]

/forums/images/graemlins/laugh.gif /forums/images/graemlins/laugh.gif A splitter /forums/images/graemlins/laugh.gif /forums/images/graemlins/laugh.gif oh that's brilliant /forums/images/graemlins/laugh.gif /forums/images/graemlins/laugh.gif you're killin me /forums/images/graemlins/laugh.gif /forums/images/graemlins/laugh.gif

 

[ShipsWoofy]

[ QUOTE ]
Thanks for the response. The in question boat is a Narrow boat so I don't have a screen. It's much simpler with Ashanta in Devon!!

Thanks everyone for your help

[/ QUOTE ]

Ooh it must be dark on board.

My car has a window aerial, the small'ish back (side) window on an estate. It really is a neat solution, though not on a window you wish to use regularly, the heads window would be ok. It does not stop you seeing through it, but it would annoy me to see the aerial every time I was watching life go by.

My car stereo has SW too and that works remarkably well through the window aerial, though is not brilliant while driving around, too many sources of noise like pylons that wreck the signal. This is a factory fit so I can not comment on the stick on aerials from halfords etc. but I would suggest not writing this off as an idea.

If I was you though, I would buy* a DAB and get R5 with a decent quality sound.

hope this helps

<span class="small">* or get on Steve Wright on a Friday afternoon and win one</span>

 

[brianrunyard]

[ QUOTE ]
I have also bought a car aerial and fitted that directly to the radio with coax going and aerial going outside. I can get the radio 5 but the sound is masked by a noise.


[/ QUOTE ]
Do you know for a fact that the radio is ok?
I've just got 18"of wire stuck in the aerial socket and it works fine. I suspect the radio is faulty.

 

[William_H]

Agree you should make sure the radio is Ok by temporarily running it on your car battery. Car radios are usually very sensitive compared to portables so it should be OK.
The noise you hear could be interference coming from a source in the boat. Inverter water pump generator. Try switching every thing except the radio off to confirm.
The radio and the areial should be connected to the steel ship. Try this at least temporarily. If the negative wiring is not connected to the steel ship for galvanic reasons (and earthing solves your problems) then you can connect the radio and the aerial screen wire to the ship via capacitors. Almost any medium to large value like like .1 microfarrad at almost any voltage rating. A larger volt rating capacitor will be more physically robust (600 volt rating) but tiny will do. They are a few pence at a RS or Maplins or similar.
The aerial should be outside obviously with the correct cable which has the active wire inside a screen wire. The screen will connect to the radio case and the active wire to a pin in the middle. The screen at the aerial end may be connected to a piece of metal designed to contact the car body. This may be tricky to insulate and mount if you want to use the capacitor isolation.
Yes there is often a tiny adjustment through the radio case for tweaking the aerial but don't be dismayed if you can't find one.
Lastly make sure your aerial is OK . You should get continuity from rod to the centre pin on a normal rod aerial.
good luck olewill

 

[ashanta]

I did think that but the boat builders have replaced it with another new one and it's the same. Thanks

 

[ashanta]

Many thanks William. You info is very detailed and makes sense.