alanwilson
Well-Known Member
Just noticed I am no longer receiving shipping forecasts on Navtex: Inshore is fine. Set to receive both channels, all stations in range & all message types. Anyone know of a problem I've missed? Thanks
Navtex: no shipping forecast - ?
- Thread starter alanwilson
- Start date
shmoo
Well-Known Member
Sounds like you may be dropping 518kHz and only getting 490kHz, for some reason.
jbweston
Well-Known Member
Are you getting the other routine broadcasts from the relevant station - eg subfacts and gunfacts and the long range outlook? If so, and your problem is very recent - only one or two forecasts missed - then it would be worth checking with nearby boatowners that they are getting shipping forecasts in case for some reason they haven't been broadcast.
If other nearby boats are getting shipping forecasts from your station, and you are getting other broadcasts, probably you need to double check that your receiver is set to recieve them (ie not 'ignore' weather). My set will allow me to turn off some message types but not others, but I can't remember if weather is one of them.
If you aren't getting other routine broadcasts from any stations (and at the same time other boats are and you used to get them in the same location as you are now), then it sounds like aerial trouble or receiver breakdown. As a first step, trace the run of the aerial cable and check the connections to make sure they haven't got disconnected and the cable itself to make sure it hasn't got snapped (eg by kedge landing on it in a locker). Also does your receiver have an earth cable (many/most don't need one)? If so check that too.
All that assumes you are getting the display to light up when you turn it on. Even if you are it might be worth checking the power cable and that the receiver is staying on in case it's going off when you aren't looking (say powers up, works for five minutes then disconnects until you come back tweleve hours later and press a button to find no forecast without relaising it's been u/s in the meantime).
In my experience as navtex user (definitely no specialist radio knowledge) navtex appreciates a good feed from its aerial but it isn't very high tech - it's basically a medium wave receiver like the old tranny radios and even a bit of wire stuck in the back of mine will produce some sort of results on screen if the station signal is strong - not as good as the proper aerial but enough to test that the receiver isn't dead.
Remember also you'll get better reception at night (even though the station should up its power during the day to compensate) so if the timing of the forecast you are expecting is day time even with a good set-up you might not get it, but you might get a night signal (eg nav warnings) from the same station OK at night.
Frank Singleton has an excellent page on navtex problems here
http://weather.mailasail.com/Franks-Weather/Navtex-Reception-Problems-And-Cures
It's a case of trying to rule out what the problem can't be and then home in on the cause.
Let us know how you get on. I think navtex is a brilliant service and well worth the effort of getting it to work reliably.
If other nearby boats are getting shipping forecasts from your station, and you are getting other broadcasts, probably you need to double check that your receiver is set to recieve them (ie not 'ignore' weather). My set will allow me to turn off some message types but not others, but I can't remember if weather is one of them.
If you aren't getting other routine broadcasts from any stations (and at the same time other boats are and you used to get them in the same location as you are now), then it sounds like aerial trouble or receiver breakdown. As a first step, trace the run of the aerial cable and check the connections to make sure they haven't got disconnected and the cable itself to make sure it hasn't got snapped (eg by kedge landing on it in a locker). Also does your receiver have an earth cable (many/most don't need one)? If so check that too.
All that assumes you are getting the display to light up when you turn it on. Even if you are it might be worth checking the power cable and that the receiver is staying on in case it's going off when you aren't looking (say powers up, works for five minutes then disconnects until you come back tweleve hours later and press a button to find no forecast without relaising it's been u/s in the meantime).
In my experience as navtex user (definitely no specialist radio knowledge) navtex appreciates a good feed from its aerial but it isn't very high tech - it's basically a medium wave receiver like the old tranny radios and even a bit of wire stuck in the back of mine will produce some sort of results on screen if the station signal is strong - not as good as the proper aerial but enough to test that the receiver isn't dead.
Remember also you'll get better reception at night (even though the station should up its power during the day to compensate) so if the timing of the forecast you are expecting is day time even with a good set-up you might not get it, but you might get a night signal (eg nav warnings) from the same station OK at night.
Frank Singleton has an excellent page on navtex problems here
http://weather.mailasail.com/Franks-Weather/Navtex-Reception-Problems-And-Cures
It's a case of trying to rule out what the problem can't be and then home in on the cause.
Let us know how you get on. I think navtex is a brilliant service and well worth the effort of getting it to work reliably.
Last edited:
Bilgediver
Well-Known Member
As others mention it seems you are not tuning in 518 mhz If you have a suitable radio which tunes this on side band have a listen also you could get a long length of wire and attach it to your antenna connection instead of the active antenna to rule out a fault in the antenna circuits. A bit if speaker flex 20/30 FT will give good results though less may also work. do not short the antenna connections as they carry 5 volts to power the active antenna. You just need to connect the centre pin for a wire antenna.
alanwilson
Well-Known Member
Many thanks for comments: the Navtex is definitely set to receive 518, but looking at the raw data received, it is 90% garbage. 490 messages (eg Inshore forecasts) are fine.
How can the set receive 490 fine but not 518? It's the same aerial!
Any ideas?
How can the set receive 490 fine but not 518? It's the same aerial!
Any ideas?
earlybird
Well-Known Member
[QUOTE
How can the set receive 490 fine but not 518? It's the same aerial!
Any ideas?[/QUOTE]
IIRC, my old dual frequency NASA aerial was in fact two aerial circuits in the same housing, one tuned to 490 kHz, the other to 518 kHz with the outputs going via an external change-over switch.
Yours might be a somewhat similar arrangement, with one half damaged in some way.
How can the set receive 490 fine but not 518? It's the same aerial!
Any ideas?[/QUOTE]
IIRC, my old dual frequency NASA aerial was in fact two aerial circuits in the same housing, one tuned to 490 kHz, the other to 518 kHz with the outputs going via an external change-over switch.
Yours might be a somewhat similar arrangement, with one half damaged in some way.
alanwilson
Well-Known Member
Problem solved! Let this be an awful warning...
Nothing wrong with aerial or reception: the station details for Niton 518 were wrong. Either they've been changed since I got the Navtex, or they were in wrong as default. Just spent a happy hour reprogramming it: messages received fine (they were being received all the time; but filtered out due to wrong lat & long).
Nothing wrong with aerial or reception: the station details for Niton 518 were wrong. Either they've been changed since I got the Navtex, or they were in wrong as default. Just spent a happy hour reprogramming it: messages received fine (they were being received all the time; but filtered out due to wrong lat & long).
jbweston
Well-Known Member
Glad you've sorted it.
Funny how we expect big trouble but often it's something small, eh?
Funny how we expect big trouble but often it's something small, eh?
theoldplucker
Well-Known Member
Changed the boat last year, which has a Nasa Navtex. Just picks up garbled characters. Probably needs programming. Refer to manual, which says it is quite easy - not so. Had a few goes at it, but can't be doing it correctly as still comes up with garbled messages. Is there an idiots guide to programming this unit ?
jbweston
Well-Known Member
Don't know if there's an idiot's guide, but I use a NASA Clipper navtex, so I'm happy to be your idiot if that's any good to you . . .
theoldplucker
Well-Known Member
Thanks for the offer. Would appreciate step by step above what is the manual for Clipper Navtex.
jbweston
Well-Known Member
OK will do my best. Just started a new thread here
http://www.ybw.com/forums/showthread.php?p=2529395#post2529395