View Full Version : Nasa pc navtex pro problems.

22-05-07, 18:03
Just got a new laptop and can't get it to talk to my PC navtex pro. Worked fine with old laptop. I'm using a maplin usb to serial lead. I can get nav software working if I connect the lead to gps and can see the data coming from gps using hyperterminal, but nothing coming from navtex. Power seems fine into navtex. Interestingly, I get a connection OK message on the suppliednasa software if com port set to com3, even when 9 pin disconnected from navtex (but obviously no messages). On startup usb/serial is seem either on com 4 or 5, set nasa software to appropiate com port and get connection no message. Any ideas? Any other way to see if unit is working? No leds on unit to show if it's on or not.

22-05-07, 18:46
Update. Put a meter across pins 2 and 5 of the serial lead, getting some volts (varies, between 1 and 2 ac) from gps but nothing at all from navtex. Maybe it's bust.

23-05-07, 03:37
Update. Put a meter across pins 2 and 5 of the serial lead, getting some volts (varies, between 1 and 2 ac) from gps but nothing at all from navtex. Maybe it's bust.

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hmm, that is a possibility but your statement in the original posting, it works fine with the old laptop makes me wonder..

When fault finding, the first and most important thing to do is trace your steps, especially when a major change has been made, in this case the changes are; a new laptop and a serial to usb converter.

Can you still use the old laptop to prove the navtex. How does the navtex get it's power, is it supposed to get power from the laptop serial, maybe the adapter does not power up the aerial as it needs? (I don't know how they work so am making assumptions here)

Have you moved the aerial during the changeover, could you have disturbed anything, blown a fuse? I blew the fuse in my nasa active aerial relatively easily when wiring it up, it is only light.

I don't know if you will see anything on the pins unless it is receiving a signal, I am not sure if you should rely on this as a definate.

If you can not get access to the old laptop, can you bring the aerial home and put it into the home PC serial port and leave it running, showing the Spectrum analyzer (this may or may not be in the nasa software, the clipper navtex has one so I am assuming they have the facility on the PC), this showed me that my old aerial was goosed, a very useful facility.

It is very odd to be completely dead, that is usually power supply rather than a radio fault, but as I said I am not sure how nasa configure these things, is it just an SSB fixed receiver, like the NASA Target HF3, if that was the case, bunging the wires to a line in on a hifi should work. The only reason I suggest this, I have the M version of the HF3 which comes with a serial-in connection and it would make sense that nasa are using the same technology over their platforms, in that, the PC navtex is a cut down NASA Target HF3 receiver without the tuning.

The last para is at your discretion, I am guessing from afar on that one, but if you bunged the wires into the line(mic) in on an old tape deck it should not do any harm, I will probably be corrected by doomsayers concerning rape, pestilence and famine upon your home, but currently you think the thing is dead, so what harm etc.

Hope this may give some ideas..

23-05-07, 10:18
The nasa pc navtex stores all the messages in it's memory so, even if the unit isn't now receiving, you should still be able to read old messages from memory. I would agree with Dogwatch that it is worth checking the set up with the old computer if that's possible. Check the settings, fiirstly that the correct port is selected and the correct data rate is being used. (38400 baud)
Finally, for reasons no one understands, some USB adapters are a bit picky and will not work wth some periferals. Nasa supply a low cost one which thay say works with any of their kit

23-05-07, 18:50
the usb to serial cables often give problems. make sure that all your kit is talking and listening through the same com port. in particular, open settings>control panel>system>hardware>device manager scroll down to ports and you should (with all the kit connected up and switched on) find a driver. possibly from prolific. open this up, look at the advanced tag and make sure it shows the com port you have decided to use. if necessary check the com settings ie baud rate, stop bits etc.

on a different subject altogether, dont forget that the navtex messages are sent on a time cycle and receivers chose which one to listen for, make sure you have it set to listen for the one that you want and check the time scedule.

phone nasa - they are very helpful.

24-05-07, 16:25
Previous laptop dead so not an option. Have just found coms settings for the unit so will try that. Yes, is prolific drivers. Seem to work fine between nav software and gps, just the navtex playing up.
Thanks for help everyone.