Replacement Navtex antenna

[SvenglishTommy]

The original antenna for my NAV 4 plus was stolen so I need to replace it. Does anyone see any issue with using the Nasa antenna (less than £30) instead of the ICS replacement antenna (£80).

It's currently just wired to the backstay and works fine like that, so I guess the Nasa should also work?

 

[duncan99210]

If it's owkring wired to the backstay, why bother changing it? Could also use a splitter with the VHF antenna?

 

[Bilgediver]

If it's owkring wired to the backstay, why bother changing it? Could also use a splitter with the VHF antenna?

The backstay is fine or a long length of wire. A VHF is not suitable as too short without the active device.

 

[st599]

If it's owkring wired to the backstay, why bother changing it? Could also use a splitter with the VHF antenna?

No you couldn't. It would be pointless to use a 160MHz antenna to receive a 500kHz signal - just think of the mismatch in wavelength.

 

[Salty John]

No reason why the Navtex aerial shouldn't work - assuming the fittings are compatible.
You just need a 512 to 490 kHz antenna. The Navtex is powered and is therefore compact in size. A passive long wire, 10m to 12m I suppose, would also work which is why your backstay is doing a reasonable job.

 

[DipperToo]

No reason why the Navtex aerial shouldn't work - assuming the fittings are compatible.
You just need a 512 to 490 kHz antenna. The Navtex is powered and is therefore compact in size. A passive long wire, 10m to 12m I suppose, would also work which is why your backstay is doing a reasonable job.

I used an old NASA aerial at first on an ICS NAV6 .... BUT, the NASA is powered and runs off 5V so you would need to have a small circuit to provide that.

I have now fitted an active V-Tronix aerial (AA20) which is powered and the voltage is supplied via the coax by the NAV6 via selectable jumpers.

 

[haydude]

Would a link to the mast or shrouds also work as well as the backstay?

 

[Billjratt]

Please, if you're going to use the rigging as an aerial for a device like a navtex which usually has an active aerial, fit a small 0.1uF capacitor in series with the lead.
Active aerials are fed with a voltage from the device and the capacitor will block that DC but allow the AC (rf) signal to pass through.
We've all got enough problems with underwater fittings rotting electrically, let's not bring the rig down as well.
A separate insulated wire hoisted partially or fully up the mast will do just as well.
You don't need a 'tuned' length unless you're transmitting (but it may collect less interference)

 

[pvb]

Please, if you're going to use the rigging as an aerial for a device like a navtex which usually has an active aerial, fit a small 0.1uF capacitor in series with the lead.
Active aerials are fed with a voltage from the device and the capacitor will block that DC but allow the AC (rf) signal to pass through.
We've all got enough problems with underwater fittings rotting electrically, let's not bring the rig down as well.
A separate insulated wire hoisted partially or fully up the mast will do just as well.
You don't need a 'tuned' length unless you're transmitting (but it may collect less interference)

He said he has a NAV4 Plus, which uses a passive antenna.

 

[SvenglishTommy]

Yes it is passive, but can also use active ones if required. Are all the NASA antennas active, there seem to be more than 1 type available?

 

[nigelmercier]

The original antenna for my NAV 4 plus was stolen so I need to replace it. Does anyone see any issue with using the Nasa antenna (less than £30) instead of the ICS replacement antenna (£80).

I'd be inclined to sell the Nav4 Plus on eBay and put the money towards the NASA Clipper Navtex system with a screen. At least it won't wake you up at 4am! Not that I'm a fan of NASA stuff, but a Navtex isn't that critical.

Speaking of the Nav4 Plus, has anyone got a schematic diagram or service manual? I'd love to modify it to give data out to my PC, would be happy to share once done.

 

[Eygthene]

Mine is a Nav4 Plus. The manual is on board. I will be in touch when I collect it, next time I go on board (could be this weekend).

 

[GAJ]

The original antenna for my NAV 4 plus was stolen so I need to replace it. Does anyone see any issue with using the Nasa antenna (less than £30) instead of the ICS replacement antenna (£80).

It's currently just wired to the backstay and works fine like that, so I guess the Nasa should also work?

We have a Nav4 and I like it 'cos it prints as I have difficulty remembering all that text on an screen, too much rum I suppose I've had the NASA and Furuno and ICS but this old thing I like.

It used to use the backstay but I now use that for my SSB so I use a NASA active antenna with a little circuit I made with to provide the 5v the NASA antenna needs, it will not work without the supply.
It works very well indeed, much better than the long wire. It receives stations from the continent without problem even in deepest darkest Lancashire.

 

[GAJ]

I'd be inclined to sell the Nav4 Plus on eBay and put the money towards the NASA Clipper Navtex system with a screen. At least it won't wake you up at 4am! Not that I'm a fan of NASA stuff, but a Navtex isn't that critical.

Speaking of the Nav4 Plus, has anyone got a schematic diagram or service manual? I'd love to modify it to give data out to my PC, would be happy to share once done.

Yes why is it always that time when the blasted thing starts to print!!
It took me a year of disturbed nights before I bothered to read the manual and find out about SILENT MODE.
Just press 'Y' before turning in and all is quiet until you press it again to print the stored messages, still forget to do it though after a good night..........

 

[Eygthene]

We have ours set for the Inshore forecast which is much longer than the Shipping forecast. Consequently even in "silent" mode, it starts up when the memory gets full and sometimes wakes us up in the small hours. Quite irritating, but I do like to get a regular update of the forecast, so can't complain.

 

[stav]

The ariel (antenna?) seems to not be recieving the respect it deserves here. Not that I know anything about these systems but surely anything will work when recieving a strong signal, my AIS was recieving two singals with no antenna plugged in the other day from ships 200 to 300m away (in harbour). Also in my experience when tucked up rivers in France my furuno 300D recieved signals when a previous NASA set had not. So would always go for the best ariel available? Although the new boat has a NASA engine and will stick with it for cost reasons and the fact that when away from regular forcasts I tend to use the mobile phone now.

 

[nigelmercier]

Just press 'Y' before turning in and all is quiet until you press it again to print the stored messages, still forget to do it though after a good night..........

I always forget!

 

[Eygthene]

Nigel

PM sent re Nav4 plus manual.