Radio problem

[Ricco1]

Bit of a strange one this. I live aboard, I have a car type radio/ cd player installed on the ceiling of my boat. The ariel is a car type, metal bulb thing with a 12 inch plastic coated ariel, fitted through the roof of the boat.

 

Until a few weeks ago this worked fine, clear reception for all channels, wherever I moored.

 

That changed a few weeks ago. Since then I've only been able to pick up radio 3 and 4, and pretty bad reception at that. Other channels are very poor reception, or nil.

 

The obvious thing was to check the ariel. If I disconnect the ariel lead from the radio the signal goes completely so this proves there's nothing wrong with the radio, and that the ariel is doing at least something. Where the ariel goes through the roof, a screw fitting, there was lots of corrosion. I cleaned this up and replaced the rusted bolt with a new one.

 

The above made no difference.

 

The strange thing here is that for the last few nights I've tried switching the radio on late at night. Each time I've had perfect reception on all channels. When I try the same channels the next morning I have very poor reception, or nothing. This suggests to me that there's nothing wrong with my set-up, that the radio signal is good at night but very poor during the day.

 

Anyone got any ideas what's going on here?

 

Thanks

[nicknorman]

Maybe something turned on during the day is causing interference, such as a laptop or phone charger?

[Tony Brooks]

Water in aerial lead/base or poor connection between aerial base and boat roof.

[Ricco1]

Maybe something turned on during the day is causing interference, such as a laptop or phone charger?

 

Thanks it's the same even if nothing else is switched on/ charging.

Water in aerial lead/base or poor connection between aerial base and boat roof.

 

I'll give it a better clean-up then, or maybe buy a new one. Why might I get perfect reception at night though?

[EmmaB]

..

Edited May 3, 2014 by EmmaB

[John V]

the fact you are getting no reception with no aerial and some with it plugged in suggests that the feeder cable is probably ok and you are receiving the stronger stations on that. This means that the most likely problem is a poor or shorting connection at the aerial end. The improvement at night could indicate either the change in temperature is causing a short circuit to open or that any increase in moisture is causing a contact to be made.

 

 

edited to add ...usually less frustrating to throw the aerial away and replace it

Edited May 3, 2014 by John V

[Tony Brooks]

 

Thanks it's the same even if nothing else is switched on/ charging.

 

I'll give it a better clean-up then, or maybe buy a new one. Why might I get perfect reception at night though?

 

Wot John said, plus contraction of the metal "bolt" holding the aerial on the roof making better contact.

 

EmmaB's idea is worth investigating if you have solar but a lack of aerial earth will tend to make it worse.

[Alan de Enfield]

EmmaB, on 03 May 2014 - 09:11 AM, said:

..

 

 

 

.

 

EmmaB's idea is worth investigating if you have solar but a lack of aerial earth will tend to make it worse.

 

Certainly one of EmmaB's better posts.

[JDR]

Radio reception can improves at night due to changes in the upper atmosphere and ionosphere. With no solar radiation the ionosphere acts as a better reflector for some frequencies.Also a reduction in background noise at night for same reason.

[ditchcrawler]

I have car radios with rubber duck aerials and the reception is crap. From day one with brand new clean bolts shiny metal and every thing as good as it could be they were crap. A bit of insulated wire twisted round and hanging off the top of the aerial improves them a lot.

[Chalky]

Radio reception can improves at night due to changes in the upper atmosphere and ionosphere. With no solar radiation the ionosphere acts as a better reflector for some frequencies.Also a reduction in background noise at night for same reason.

 

Beat me to it! Radio amateurs often use the changes in the ionosphere to communicate with stations at further distances than their sets (rigs) are usually capable of.

[John V]

Radio reception can improves at night due to changes in the upper atmosphere and ionosphere. With no solar radiation the ionosphere acts as a better reflector for some frequencies.Also a reduction in background noise at night for same reason.

 

You mean there are still people in this country listening to am ?

[bizzard]

Yes I have a wireless set but tend to listen to it in the afternoon and not the morning.

[aread2]

It's not one with an amplifier in the base of the aeriel is it? If the power connection to the base of the aeriel has failed, the performance would be affected.

[Tony Brooks]

It's not one with an amplifier in the base of the aeriel is it? If the power connection to the base of the aeriel has failed, the performance would be affected.

 

And they get water over the amplifier circuit board that dries, over time, to scale that then gets damp. That causes such problems as well. I have "cured" this by taking the aerial off, carefully unscrewing the base of the aerial (often two small screws from underneath), cleaning the board, smothering in silicon grease and reassembling.

[lockedout]

Only slightly off-topic...

 

We had all sorts of aerial based problems - bought a mid-range DAB car radio, stuck the aerial to the window (mostly hidden by the curtain) and it works brilliantly!

 

SO pleased with it - all those channels, everything from 6Radio to Al-Jazeera (sp?).

[Ricco1]

OK I've tried everything I can, no improvement. I'm thinking now of cutting off the plastic fitting that holds the bolt that goes through the hull to connect with the ariel 'bulb'. Then I'll crimp a spade connector to the bare wire, clean the underside of the boat's roof to bare metal, shorten the bolt then screw it all together. Any thoughts on that?

 

Otherwise, could someone maybe suggest an inexpensive ariel I could buy as a replacement? I already have a 12mm hole in the roof, or don't mind having it inside the boat and filling the hole. Thanks.

[ditchcrawler]

OK I've tried everything I can, no improvement. I'm thinking now of cutting off the plastic fitting that holds the bolt that goes through the hull to connect with the ariel 'bulb'. Then I'll crimp a spade connector to the bare wire, clean the underside of the boat's roof to bare metal, shorten the bolt then screw it all together. Any thoughts on that?

 

Otherwise, could someone maybe suggest an inexpensive ariel I could buy as a replacement? I already have a 12mm hole in the roof, or don't mind having it inside the boat and filling the hole. Thanks.

I was thinking of using a proper car aerial

[John V]

as I said in post #6....usually less frustrating to throw the aerial away and replace it

[ditchcrawler]

as I said in post #6....usually less frustrating to throw the aerial away and replace it

That is what I did and it was still crap

[Radiomariner]

Have you checked the aerial co-ax for continuity and shorts? Either could cause your problem.

In addition to the obvious, the "front end" of the radio is matched to the co-ax which is matched to the aerial and any such physical change (including water ingress) can upset this matching and drastically reduce the radio's sensitivity. After dark signals can improve due to factors described in an earlier post

My chief suspect would be water ingress to the co-ax, (the braided outer shield can corrode as well), a break in the inner core (usually where there are kinks or sharp bends). Another consideration is badly made or badly fitting co-ax connectors

The aerial connection at the back if the radio working loose often causes a similar symptom. When new the contacts are self cleaning as they slide in. Over time the springy bits loose tension, the contact surfaces oxide over and make poor contact. For this reason the cable should not be stretched tight so that any vibration may tend to pull it out, or too long and unsupported so the cable weight puts a strain on the plug.

Hope this has been of some help.

[John V]

as per radiomariner, but question? do you use a car radio type extension lead between the plug on the lead fitted to the aerial or does it plug in direct to the radio?

[pearley]

That is what I did and it was still crap:angry2:

But did you replace the cable?

[Jamesandlinda]

Better reception at night is quite normal. It's just that you never noticed the less good reception in day time because it was plenty good enough.

 

It does sound like the aerial has died. I would recommend replacing it.

[PeterDHS]

Hi Ricco,

Just a thought.......when I fiited a car radio many moons ago I took advice that basically said I should not rely on a hull/shell connection as an aerial earth. It is not like a car where the body is purposely wired to negative. I was told it was OK to fit the aerial as long as I put a capacitor thingy in the positive line to prevent earthing the entire boat via the canal with consequent burnt wires etc.

Could it be that you have something similar and the capacitor has over-loaded and fritzed ?

 

Peter.