SSB receiver - need special antennas?

[CharlesM]

Hello all

As I am off to the Caribbean in about 16 days /forums/images/graemlins/grin.gif (who's counting) and all the learned people here inform us of the suitability of an SSB down there for weather etc, I am considering installing a SSB receiver (as a transciever is a little expensive at this point given the loads of other stuff I need to install) - and the legality of the various sets is in question.

My question - Do I need one of those special antennas AT-130 or 140 which are around $500, or will a bent coathanger work?

Advice would be greatly appreciated.

Regards
Charles

 

[steve_cronin]

Rather than a bent coathanger, a length of single wire is quite effective but it's length is dependant to some extent on the frequencies to be covered. For weatherfax & RTTY around 30ft is suitable. Some sets, like the NASA have an active stub antenna which works well. Mine receives the German station Offenbach and the UK station Northwood satisfactorily in Greece. Other people insulate the ends of their backstays and link onto that as an antenna. Siting is the most important factor, getting the antenna into clear air away from structures that might annenuate the signal.

Steve Cronin

 

[Strathglass]

A piece of wire running up to the spreader on the flag halyard should be adequate. Use a tie-wrap as an insulator at the top.

An ATU would help a little on week signals but probably not justified.
You can get low cost manually tunable, recieve only ones from Ham radio outlets. They used to be under £50, don't know current pricing.

You can try a wire out just by running a wire out the hatch.
Use flexable multi strand wire. It doesn't have to be particurally thick and I don't think it justifies special marine wire, more bell wire from Maplin or B&Q.

Cheers

Iain

 

[Birdseye]

[ QUOTE ]
Hello all

As I am off to the Caribbean in about 16 days /forums/images/graemlins/grin.gif (who's counting) and all the learned people here inform us of the suitability of an SSB down there for weather etc, I am considering installing a SSB receiver (as a transciever is a little expensive at this point given the loads of other stuff I need to install) - and the legality of the various sets is in question.

My question - Do I need one of those special antennas AT-130 or 140 which are around $500, or will a bent coathanger work?

Advice would be greatly appreciated.

Regards
Charles

[/ QUOTE ]

The length an aerial should be is related to the wavelength of the signal you are trying to hear / send - what an aerial tuning unit does is in effect to con the set into thinking the aerial is a different length to what it actually is. And as a guide, the wavelengths you will be using are typically from 40metres to 20.

But this is much more important with a transmitter than a receiver - not least because a real mismatch will either fry your transmitter or cause it to shut down. So you will still be able to receive without a tuning unit and using a simple length of wire, the longer the better. But the signal will be less strength than it ideally could be. Personally, I wouldnt spend the exra money - decent receivers are very sensitive.

But dont try transmitting into the bent coathanger!

 

[TigaWave]

We ran coax to the transom and then just spiralled the thin wire (supplied with Target receiver) up the back stay,...great reception.
You do get noise from other electrical installations, try switching every thing else off first before you blame the aerial.

 

[CharlesM]

Thanks all

I will avoid the coathanger, but will give the wire a try. Pleased to hear I dont need a special antenna.

cheers
Charles

 

[mapron]

I've got an SSB receiver but I've been put off using it by complicated wiring arrangements for the aerial involving special insulators. I'm interested in trying your method but could you give a bit more detail? Don't you need to insulate the wire from the backstay? What kind of coax do you use and what connection do you make at the ends? Thanks, Allan

 

[Benbow]

The method TigaWave describes will work well only if the backstay is already insulated from the sea. On a plastic boat this insulation is usually good enough for receiving; effectively the whole rig becomes the antenna and is isolated by the hull.

With a reasonable length of wire it therefore makes (almost) no difference whether or not you remove the insulation - I would not because of corrosion concerns. But the RF doesn't care. Alternatively - again on a plastic boat - you will often get a perfectly good antenna for receiving if you can attach your antenna wire to the bolts where the backstay attaches to the inside of your hull. Just strip back a bit of insulation and attach it.

I would add that, if you are interested in playing, more esoteric aerials such as tuned dipoles can give spectacular improvements in reception of weak and distant signals but will really not help with the general local broadcasts which you are probably after.