Navtex replacement antenna

[Babylon]

I have a slightly older Navtex with two antennas and a toggle switch to switch between them. One never seems to work and I'd like to get rid of it, but I don't know which actual antenna it is - nor do I know why the boat was fitted with two in the first place.

Any suggestions - and any explanation for the doubling-up?

 

[Bilgediver]

I have a slightly older Navtex with two antennas and a toggle switch to switch between them. One never seems to work and I'd like to get rid of it, but I don't know which actual antenna it is - nor do I know why the boat was fitted with two in the first place.

Any suggestions - and any explanation for the doubling-up?

Navtex was originally transmitted on a single frequency. Later on another service was added on a second frequency and as the tuned RF circuits are in the antenna base then some manufacturers coped by supplying a second antenna tuned to the new frequency.

Tell us what Navtex you have, what you see on the screen and what is written on each antenna and we might be able to help.

 

[Babylon]

Not on boat but from memory its a NASA Navtex, screen about 2" high, with three control buttons on right hand side: up, down and enter. Below the unit is the separate toggle switch. The cables are routed behind bulkheads, panels etc, so no easy mechanical way to figure which antenna is A and which B. All printing on both white tubes is gone.

Would I need to replace both antennas with a single new unit?

 

[earlybird]

Not on boat but from memory its a NASA Navtex, screen about 2" high, with three control buttons on right hand side: up, down and enter. Below the unit is the separate toggle switch. The cables are routed behind bulkheads, panels etc, so no easy mechanical way to figure which antenna is A and which B. All printing on both white tubes is gone.

Would I need to replace both antennas with a single new unit?

Sounds like a Nasa Target Pro or Pro+. I had an early version.
Early on, the system worked on single frequency, 518kHz only. Later, 490kHz was introduced for local weather. Nasa dealt with this by introducing a replacement switchable 2 frequency aerial, but I don't remember a stand-alone 490kHz aerial, so why you have two is a mystery to me.
The aerials were not particularly waterproof, so that might be the problem with the one.
You can still buy aerials if you think it's worth it.
I would contact NASA, who I've found very helpful by 'phone and e-mail.

 

[prv]

Early on, the system worked on single frequency, 518kHz only. Later, 490kHz was introduced for local weather. Nasa dealt with this by introducing a replacement switchable 2 frequency aerial, but I don't remember a stand-alone 490kHz aerial, so why you have two is a mystery to me.

That matches my understanding, but I kept quiet in case there was a Nasa 490khz aerial I didn't know about

The Pro Plus I inherited had a switch, in a separate box a few inches down the cable from the display, but it didn't switch between two different aerials. It switched what you received from the single dual-frequency aerial.

When you say one of the aerials doesn't work, what exactly are you receiving and not receiving? What filters do you have set in the display?

Pete

 

[xeitosaphil]

Sounds like a Nasa Target Pro or Pro+. I had an early version.
Early on, the system worked on single frequency, 518kHz only. Later, 490kHz was introduced for local weather. Nasa dealt with this by introducing a replacement switchable 2 frequency aerial, but I don't remember a stand-alone 490kHz aerial, so why you have two is a mystery to me.
The aerials were not particularly waterproof, so that might be the problem with the one.
You can still buy aerials if you think it's worth it.
I would contact NASA, who I've found very helpful by 'phone and e-mail.

I have a Nasa Navtex Pro+ and also with two aerials – one 490 kHz and one 518 kHz also a toggle switch over switch.
One aerial is used for local transitions ( 490khz ) but 518khz is used for European transitions also sent out in local language sometimes. Depends how you have your receiver set up for Stations and Messages. Check out Reeds Navtex pages for setting Stations frequencies, message types and areas etc.
Mine both work, but I find 490 kHz set mostly to Niton Radio suits me. I have also wondered if a combined dual frequency aeriel would work with an older set, but as mine are still working ok haven’t bothered to pursue it.
Incidentally mine are both fitted inside the heads on the two separating bulkheads over the hanging locker and work fine down below, so no waterproofing problems.

 

[Babylon]

Thanks. It is a NASA Target (Pro).

Is it worth it? I don't know. Now that I have a smartphone for downloadable GRIBS, in addition to CG Met Office broadcasts around the coast, I almost never even switch the Navtex on. But in the back of my mind I see it as a backup when offshore sailing.

 

[prv]

Is it worth it? I don't know. Now that I have a smartphone for downloadable GRIBS, in addition to CG Met Office broadcasts around the coast, I almost never even switch the Navtex on. But in the back of my mind I see it as a backup when offshore sailing.

Just depends how you will use the boat. Kindred Spirit came with a Navtex (same model as yours), but I removed it because I couldn't forsee any circumstances in which I would take that boat out of mobile phone range for more than the time it takes to cross the Channel.

On Ariam, I've bought an ICS display to use initially as a below-decks instrument repeater, but I have every intention of sooner or later adding the radio receiver box and aerial to get Navtex data because I hope to use this boat to go further afield.

Pete

 

[earlybird]

Seems like NASA may have sold a separate 490kHz aerial, I don't recall it, but it was 15+ years ago.
I've looked on their website, and it doesn't appear there now.
At the time, I updated mine by buying the 2 frequency aerial, which included the little box and switch.
As I remember, the aerials weren't too pricey, and there seems little point in having two, rather than a combined one.
If you haven't got the instructions, maybe worth downloading. Operation of the unit is not very intuitive.

 

[Babylon]

Seems like NASA may have sold a separate 490kHz aerial, I don't recall it, but it was 15+ years ago.
I've looked on their website, and it doesn't appear there now.
At the time, I updated mine by buying the 2 frequency aerial, which included the little box and switch.
As I remember, the aerials weren't too pricey, and there seems little point in having two, rather than a combined one.
If you haven't got the instructions, maybe worth downloading. Operation of the unit is not very intuitive.

Thanks for this history. You're right! Its a complete pain to programme, but this should get easier the more one uses it.

I also need to replace the NASA MW/LW radio receiver antenna as well, so it makes sense to drop them a line.

BTW I like independent systems so as to maintain a level of redundancy, so it makes sense to revive these two bits of kit.

 

[Bilgediver]

I have a slightly older Navtex with two antennas and a toggle switch to switch between them. One never seems to work and I'd like to get rid of it, but I don't know which actual antenna it is - nor do I know why the boat was fitted with two in the first place.

Any suggestions - and any explanation for the doubling-up?

Your second antenna was the first fix . They then came out with the combined antenna. Why
not speak to Nasa and see whether the dual antenna is a straight swap and see if you are
happy with the cost.

I personally would go for a used Furuno.

Manual

http://www.nasamarine.com/images/file/Target Navtex Pro.pdf

 

[Babylon]

Spoke to NASA. My old Pro-Plus receiver won't work with a modern replacement single antenna, but they'll sell me a discounted complete replacement for £150 px for the old unit back.

The current version has a slightly larger font size, which will certainly help me!

 

[FullCircle]

Spoke to NASA. My old Pro-Plus receiver won't work with a modern replacement single antenna, but they'll sell me a discounted complete replacement for £150 px for the old unit back.

The current version has a slightly larger font size, which will certainly help me!

Bargain - good customer service.