Do I send my Clipper Navtex back to NASA?

[JumbleDuck]

[Follows on from a thread ages ago: http://www.ybw.com/forums/showthread.php?390523-Working-Clipper-Navtex-around-the-Forth]

I have an NASA Clipper Navtex - an early one, I guess, as it is serial number 125. In the five years I have owned it I have never seen a message on it. General opinion was that the aerial was the most likely culprit, so I brought it home to test with a wire aerial ... and forgot about it until yesterday.

It's now sitting in the back porch, attached to 30 feet of wire running across the garden and running off a 12V power supply. All screens and menus appear as they should, and it is set to receive all messages from all stations, national and international. Radio reception isn't great here, as we're at the bottom of a small dip, but we are only about 50 miles from Portpatrick.

Nada. Nichts. Zapoo. Zilch. Nanti Navtex. Not a sausage. Just "Int Sby" or "Nat. Sby" bottom left and, if I scroll down, a row of octothorpes (###################). Occasionally a few letters appear bottom left, on the same line as the standby message, but they disappear again after a bit.

Do I (a) try again somewhere else (b) send it back to NASA and ask them to look at it or (c) bin it?

I have had a look inside, by the way, and there is no sign of the battery leaking or of any other damage.

 

[pvb]

(c)

 

[David2452]

The people at NASA are unusually sympathetic and helpful, however my instinct would still be (c)

 

[davidej]

I think that navtex is ancient history but many don't.

I put my Nasa Target on fleabay and got nearly £200

 

[sutton sailor]

My advise is send it back to NASA . I have found them to be very helpful and their charges have always been reasonable.

 

[pvb]

I put my Nasa Target on fleabay and got nearly £200

Incredible, and demonstrates that most eBay buyers haven't got a clue.

 

[JumbleDuck]

Incredible, and demonstrates that most eBay buyers haven't got a clue.

I sold a set of Triumph Herald bonnet repair panels on eBay for substantially more than precisely the same things could be bought for, new, from the manufacturers.

 

[pvb]

I sold a set of Triumph Herald bonnet repair panels on eBay for substantially more than precisely the same things could be bought for, new, from the manufacturers.

I'm sure you did, nothing surprises me about the gullibility of eBay buyers. Some years ago, I had a nice little run of selling mobile phone cases on eBay, just as they were becoming fashionable. I was buying them on US eBay for about £3 each (after shipping) and auctioning them on UK eBay for an average of about £25.

 

[<152587>]

And it will not work with that antennae set up, needs active aerial.

 

[JumbleDuck]

And it will not work with that antennae set up, needs active aerial.

Are you quite sure? I have been very widely advised to try a simple wire aerial with it. The received signal strength display shows that something is coming in, but perhaps not enough.

 

[VicS]

Are you quite sure? I have been very widely advised to try a simple wire aerial with it. The received signal strength display shows that something is coming in, but perhaps not enough.

The instruction manual does indicate that its aerial is in fact "active". It is possible there may be some frequency change made in it, as well as amplification.

It might be worth contacting Nasa initially, They have reputation for being helpful. If they say yes it needs the correct aerial ( about £25 ) you then have to option of buying the aerial and taking it from there or sending it to Nasa to check over first .

They may "do a deal" if you say check/ repair if economical and supply new aerial at the same time.

 

[JumbleDuck]

The instruction manual does indicate that its aerial is in fact "active". It is possible there may be some frequency change made in it, as well as amplification.

It might be worth contacting Nasa initially, They have reputation for being helpful. If they say yes it needs the correct aerial ( about £25 ) you then have to option of buying the aerial and taking it from there or sending it to Nasa to check over first .

They may "do a deal" if you say check/ repair if economical and supply new aerial at the same time.

Many thanks, Vic. I'll give them a ring in the morning. I'm reluctant to buy a new aerial if the receiver is dead, so getting them to check seems sensible.

 

[ffiill]

I have tried accessing navtext on my Eaton ssb set up witha 30 foot long wire on my house roof.
Whilst I have downloaded legible weatherfax from Boston USA I have never been able to receive uk Navtext.
I did however once get a good signal from their Istanbul transmitter advicing of weather in the eastern med.plus info about the Suez canal and current pirate alerts in the Red Sea!

 

[Billjratt]

Yes they are designed to use an active aerial -hence the need to fit a capacitor if using the(insulated) backstay instead.
You can use a wire but I, like you guys, didn't have any luck in the shed after a repair.
I think it may be due to signal interference in an onshore situation rather than a specific tuning of the wire length .
Remember lots of people can't even get a decent result in a marina, they need to go out and about before it works.

 

[LittleSister]

Not only do they use an active aerial, the older ones have the switch for changing between national and international frequencies in the aerial lead, rather than in the set.

 

[SteveSarabande]

there is a frequency display page that shows if your receiving a signal

 

[JumbleDuck]

there is a frequency display page that shows if your receiving a signal

As per post #10, that does show a signal (nothing bang on frequency, nice side bands) for both national and international, but with no scale in the "strength" direction I can't tell whether it's a reasonable signal or practically nothing. I suspect it rescales the vertical axis as required.

 

[Niander]

Incredible, and demonstrates that most eBay buyers haven't got a clue.

Not true...only some!

 

[MM5AHO]

The quite low frequencies that NAVTEX is on means that the antenna need to be suitable. The "active" antenna is one way to overcome this. It doesn't change the frequency, just has a built in preamplifier, to boost the very weak signal received by an inadequate antenna.
To rig up an antenna that is suitable for these frequencies you could use one of the following suggestions: a very long long wire (the wavelength here is about 600m, you probably need at least half that); or a loop antenna (need to design this to suit frequency), a ferrite rod and coil antenna (perhaps pulled from an old Medium wave transistor radio).
None of these is an easy test, especially for a temporary setup just to test the unit. Sending back might be more fruitful.

 

[earlybird]

When I owned a NASA Target Navtex; ie not a Clipper, it would pick up 518kHz signals, but not 490kHz from stations on the S. coast and in Europe on a piece of wire a couple of metres long, but not as well as with the 'proper' aerial. But that was in a house overlooking the N. Irish Sea. Portpatrick was the nearest station, <50 miles, but reception from there was quite intermittent. Navtex reception seems to be very easily lost in general EMF noise.
Re the active antenna, when dismantled, my aerial didn't appear to have much in the way of amplification circuitry, just a couple of tiny components that may have been capacitors or resistors, or perhaps I didn't recognize them for what they were. They didn't look like chips or transistors.