TV aerial

Phoenix of Hamble

Phoenix of Hamble

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On our masthead we have some reason unknown, a spare VHF aerial, which runs back to the chart table where it terminates in an F socket connector rather than the more common VHF style connector (name I don't know!).... i've bought a convertor from F socket to TV style connector, so hopeful that it will provide a decent picture.....

Be interested in what any of you propogation/reception/aerial specialists think the likely outcome will be.... the adaptor was only £1.65, so no big deal if it doesn't work very well.... will a VHF style aerial be any use for TV reception, or will I need to fit a Glomex style aerial?
 
It depends on the reception in your area. The Glomex antenna (and I know because i have taken it apart) consists of a loop of wire inside a very nice housing with lots of foam!! There is also a small amplifier and perhaps some filtering. A smart move might be to buy a TV masthead amplifier from Maplin and use your own bit of bent wire.
 
If you are in an analogue area and have a fairly strong signal it might work. But there is a chance if you are trying for digital reception you will get nothing as many digital transmitters are horizontal and require the aerial on it's side. At home I have a little stubby aerial for the boat television that only works in the horizontal plane, it is not even as though it works but not as well in vertical, it is like a switch; a few degrees off the horizontal the picture turns off.

As you say, nothing ventured; personally I would have my scanner plugged into the spare socket.
 
As stated by other posters, the signal if strong will be ok for analogue but due to polarization differences not great for digital. You could start playing with ATUs etc to bring the antenna to resonance within the TV broadcast band - or even cut it down to size -but none of this will help with polarization. Still perfect for AIS etc

As to masthead preamps -can be a mixed blessing as are usually (unless you pay a lot for them) rather simple broadband amplifiers - the problem with this is they simply amplify everything in their passband including all the unwanted interference as well - so can sometimes (if its interference and not a weak signal) make matters worse.
 
Why not buy a cheap freeview satelite reciever and dish around £70 intended for caravans I used one last year from Dover to Paris. No good at anchor but when you are secured for and aft with a view south bbc and itv reception are crystal clear with the dish sitting on the coach roof and aligned. UHF TV reception in most marinas I have visited is usually spoilt by ghosting from masts cranes etc or by being in the shadow of cliffs / harbour walls. This year I am fitting an outboard crane which will double as a dish mount when in port I saw a Belgian boat in Boulogne with this arrangement.
 
By all means give the VHF aerial a go as a TV aerial. It may be fine in your location. Radio transmissions in VHF tend to be polarised. ie if the transmitter is horizontal then the receiver will have a huge loss unless it is also horizontal. I cant speak with wisdom of UK TV but I think it is more commonly horizontal. You can tell by looking at the local TV aerials on roofs.
VHF communications is almost always vertical. It means that strength is pretty similar in all azimuth directions.

If your TV reception is yukky on the VHF antenna that will be no surprise. You will probably get acceptable reception using a decent antenna at low levels. Start with one of those indoor aerials sitting on the cabin top and work up to an aerial with an amplifier.

Household antenna get their performance by making them directional. The added elements make the antenna work like a flashlight or dish satelite antenna. So it will only work when directed towards the transmitter. That is fine if you are in a fixed location and the boat doesn't turn and you only want to watch TV while at mooring. The vehicle /caravan type antenna )like a flying saucer) are not directional but consequently are not very sensitive in difficult areas. So it depends on what suits you. olewill
 
Follow up......

The VHF antenna was rubbish!!!!!

We got precisely nowt on it!... a small amplified desk top antenna was marginally better, in that the picture could just about be seen through the noise, and audio was present...

Looks like i'll have to buy a Glomex....
 
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Looks like i'll have to buy a Glomex....

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Triax UFO works well for me and Dogwatch. I get freeview fine in Portomaso marina in Malta - dont understand it mind.
 
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