Weather fax - Wefax

[philip_stevens]

A question for the radio amateurs.

I have a JRC Wefax machine in use at home with a long wire aerial. It works OK. What is the shortest length of wire aerial, or shortest whip aerial I would need to use it on a boat - but not permanently, so whip ae in preference.

I want to use it on occasional trips with wx from Offenbach and Northwood, on 4,6,8 megs. Mainly Offenbach on 7880 megs, and occasionally Northwood on 4307 or 6452.5 megs.

regards,
Philip

 

[terence]

well phillip the best ant to use would be the outbacker jnr its a 6ft multi band made in australia retail 106 pound sterling and you do not need a atu [ antenie tuneing unit] happy weefax terry.........stop

 

[philip_stevens]

Thanks.

I'll have a look at the Dick Smith site to find out some more details on that one. I may be able to get something similar in the UK.

regards,
Philip

 

[brian_neale]

£106 sounds like a lot of money for something that will be used for reception only. Have you had a chance to try out various antennae on your boat? For experimental purposes, try something like a long garden cane with a piece of wire running up it, and just see if it works. The high-tech equivalent is a glass fibre fishing rod blank with a wire poked up the middle! It may be all that you need, and the capital cost of a few experiments like this is just the cost of a reel of wire from somewhere like Maplin. Receiving equipment is much less fussy than transmitting equipment, and you will not damage a receiver with a mismatched antenna. I am sure that a perfectly matched, accurately tuned antenna would work better than a random piece of wire, but by how much? £100 worth better?

 

[Bergman]

BAsically you have it about right at home.

Can you do similar on boat - longest bit of wire possible.

Don't know the Aussie thing at all but cannot tune all frequencies without ATU - physically impossible!

If you must have a whip type best would be fibreglass pole.

Start at bottom of pole wind turns round the pole for about half the height, leave about half a pole diameter distance between each turn. At the half way point run the wire up to top of pole. Attached to top have a "halo" a cricle of wire around the pole connected to top of wire by 4 "spokes.

You will need an ATU to get best results. You can buy cheap receive only ATU for a relatively low price - I think around £30.

Try Maplins or the site for MFJ to start.

E-Bay may be source of one 2nd hand

If no success on these drop me a private mail

 

[Bergman]

Re: PS

Forgot to mention.

You need a decent earth connection.

Anything on boat that will give decent contact to sea. If nothing better use an anode.

 

[philip_stevens]

Re: PS

Brian and Bergman,
Many thanks for the advice. I'll have a go tomorrow with wire wound aroung a pole. I've got a reel of fine covered wire in the garage.
Nothing to lose, everything to "gain".

regards,
Philip

 

[ParaHandy]

Try an active aerial from Nasa? Costs £30 odd. My set interchanges between long wire and this active antennae.

Mixed results with Northwood recently. When they transmit on 8040 khz I rarely have trouble. They use this frequency mainly at night - ok, would expect it to be better anyway, but still... This summer they've used 2618.5 and 4610 khz during the day and reception is not wonderful - legible but only just at 2618. The other oddity is that a (very) few transmissions are not sent eg 2000z T 72 forecast last Saturday. The timing is also wandering such that the 2000z run when 4 follow each other can be several minutes early or late and, therefore, the receiver can miss the sync pulses at the beginning (if its early). (If you are useing a timed reception eg when receiver switches itself on at a partic time)


<P ID="edit"><FONT SIZE=-1>Edited by ParaHandy on 15/07/2002 12:50 (server time).</FONT></P>

 

[philip_stevens]

I find I use Offenbach more on 7880 for Wefax, so should have reasonable results. I will look into the Nasa active aerial.
My old JRC machine can be timed set, for on sync pulses, but I have to give it a set time to stay on. Then it can use up paper if it does not get the end pulse.
Many thanks for the advice.

regards,
Philip