HF radio antenna

[Hunter34]

I am looking for an antenna to use on board to use with a HF receiver (Radioshack DX394) to receive general weather info on SSB, weatherfax and Navtex (I already have the software) but I want to avoid using the backstay if possible.
Can anyone recommend any particular make or model and will I also need an ATU?

Any advice would be most welcome.

Andrew

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[charles_reed]

ATU only required for TX.

You could use an active antenna - Radio Shack used to do one.

Make sure you have a good RF earth

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[Bergman]

Best bet would be a length of wire hoisted up mast and an atu

The tuning unit is important on receive. Without one, particularly on an unbalanced aerial, you will have a significantly worse signal/noise ratio and it is this ratio that determines the quality of reception, particularly on data signals such as fax and Navtex

Earth is important too but no need to go OTT use the anode or a keel bolt, connect with one thick wire.

Never tried active aerial but deeply suspicious of them. May be acceptable for single frequency buy can't see how they can work over any useful bandwidth.

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[MainlySteam]

There is a review of the radio at <A target="_blank" HREF=http://www.rnw.nl/realradio/dx394.html>http://www.rnw.nl/realradio/dx394.html</A>. It states that it has rear connectors for both a high impedance and a low impedance antenna and that a 10 m wire is likely to be all that is needed for general listening.

Most simple receivers are made to operate into simple antennas and an antenna tuner is not worth the cost, realising little performance gain. I would suggest, if you have a fibreglass boat, just connecting it to a chainplate bolt or similar for the antenna - along the lines that Fatipa has already suggested. It is easy to check if it will work, just connect a piece of wire to the antenna connector on the radio (with the set earthed as well) and hold the other end against a chain plate to see. You will probably find it works best with the high impedance antenna connection (assuming the review is correct in claiming that it has one!).

John

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[Hunter34]

Thanks for advice

The reason I cannot use one of the shrouds as an antenna is that all the chain plates are tied to the keel via inch thick steel rods.Since I earth the receiver to the keel this wont work.
I dont really want to hoist a wire up the mast each time I want to use the set so I think I will look for a suitable active antenna.

Thanks again

Andrew

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[milltech]

Nasa do an active HF antenna that I was going to tell you is on my site at

http://www.allgadgets.co.uk/ag/product.asp?dept_id=10&pf_id=AG0047

However it's not true, no description, nothing! Just a price. So this is from the Nasa brochure, though I have no idea what its effect would be on other radios, ask Nasa 01438 354033, nasamarine@aol.com

Direct connection to HF3 & HF3/M receivers
Frequency range 30 Khz/30Mhz
Power Consumption 20mA @ 12v
Robust and Waterproof
Overall height 420mm
7 metres coaxial cable


<hr width=100% size=1>John
<A target="_blank" HREF=http://www.allgadgets.co.uk>http://www.allgadgets.co.uk</A>

 

[MainlySteam]

Re: Thanks for advice

If you are unhappy with the result using an active antenna then perhaps you could do something similar to what we do for our main SSB antenna.

It runs through the deck (using a feed through insulator which can be bought or made, and for receive only could be quite small, perhaps just a simple cable gland) to the upper spreader on a halyard - it is permanently hoisted. The deck end is just forward of the aft inner shroud to be clear of boom, mainsail, etc. In my experience the halyard needs to be of 3 or 4 mm diameter spectra braid in order to be able to get the antenna taught enough without the halyard stretching and letting the antenna flop around.

You could trial this simply by leading a length of wire out a hatch and hauling it up on the flag or any other halyard to check the reception result.

John



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