STILL awaiting Repair!!

[Fenris]

Regarding the Antenna it's the one that came with with the original unit. I live aboard a narrowboat and the antenna is kept in the front cratch under cover!

If you have a multimeter check the connection between the centre pin of the SMA connector and the screw base that the antenna element attaches to.

Some people have found that there is a problem with the soldering under the base, if you have poor contact then it is possible to repair it but it requires peeling off the sealing disk under the magnetic base.

[Jeremy]

For some reason my post has not arrived.
'Ditch,
Is your aerial in the same place on your narrowboat where you had the 75 a/c logged? If you have the antenna out from under the roof the aerial is almost surrounded by the metal frame of the narrowboat. If you put it out on top of the boat then you have the best groundplane of us all!
Jeremy.

[tarbat]

Would the lack of any earth on a narrow-boat have any effect?  Probably not, but I thought it was worth mentioning.

[Fenris]

Would the lack of any earth on a narrow-boat have any effect?  Probably not, but I thought it was worth mentioning.

No, the earth, or more correctly ground, side of the antenna is purely there to create the plane in which the antenna monopole element is mirrored. Of course that mirrored half is not actually there, but from a current flow point of view it's a necessary thing to make the equations work.

[nbquidditch]

Thanks for the suggestions guys. I don't have a multi meter Fenris I'm not THAT technical I just enjoy using RB and and happy with the standard kit :)
The antenna does sit on the roof when the weather is good and sits under the canvas cratch at the front when not and I get lots of flights with either.
I think I am earthed anyway by means of the shore line electric on the pontoon?? The antenna is in the same place as usual and I'm directly on Birmingham & Coventry approach with dozens of other flights around at peak I sometimes get 150+ and can even pick up lower level stuff going into Heathrow, Gatwick & Stanstead on a good day.

[palmar]

If you have a multimeter check the connection between the centre pin of the SMA connector and the screw base that the antenna element attaches to.

The multimeter check has the hazard that on an old-style RB the first stage filter is loaded with DC. The datasheet of the Taisaw TA1090EC device states:

MAXIMUM DC INPUT VOLTAGE = 0V

The hazard is not that dramatic if the SMA connector is DC isolated from the filter by a capacitor. (Even though a momentary connection may generate a voltage peak on the filter input).

The above hint is box suicide.
Keep off any antenna connector with external voltages!

[Fenris]

You will note that my suggestion was to measure from the antenna base to the SMA connector on the antenna cable, naturally you can only do this when the antenna is disconnected from the RadarBox.

Also note that there is a DC blocking capacitor between the antenna connection/protection device and the SAW filter, so it's difficult to put DC directly on the filter, there will be a small transient voltage though, but no more.

It occurs to me that perhaps the front end static sensitivity could be improved by having a DC ground via an inductor, that inductor could then be resonated at 1090MHz with a parallel capacitor and then it would not load the 50 ohm connection into the front end. That solution would be better than using the protection device that is used at present because it presents a dead short at DC rather than requiring some voltage to switch on that device.

[CoastGuardJon]

Hi Palmar, my reading of Brian's post is to check the continuity of the antenna lead and plug, not the RB itself.

Sorry, Brian, just seen you've posted while I was typing!

[nbquidditch]

OK guys, received my new antenna today from W&S, the standard one that comes with the original kit, and instantly upon connection I'm getting 75+ flights once more!! So all is well. My question to support is? Surely the antenna is covered within my 1 years guarantee, I’ve just forked out £22.95 for a replacement I'm surely entitled to a refund?

Cheers

[AirNav Support]

Its covered if it was a failure of the antenna totally. If its something that wear and tear caused then its not covered.

We do not advise that you use the standard antenna as an external antenna.

[nbquidditch]

The original standard antenna was used nearly always under cover and very occasionally externally during good weather! it still looks in excellent condition and shows no apparent reason for failure.

[tarbat]

I would suspect a problem with the centre pin on the antenna connecting lead - there's been several reports of problems with the centre pin on the standard antenna lead.

[palmar]

You will note that my suggestion was to measure from the antenna base to the SMA connector on the antenna cable, naturally you can only do this when the antenna is disconnected from the RadarBox.

Also note that there is a DC blocking capacitor between the antenna connection/protection device and the SAW filter, so it's difficult to put DC directly on the filter, there will be a small transient voltage though, but no more.

It occurs to me that perhaps the front end static sensitivity could be improved by having a DC ground via an inductor, that inductor could then be resonated at 1090MHz with a parallel capacitor and then it would not load the 50 ohm connection into the front end. That solution would be better than using the protection device that is used at present because it presents a dead short at DC rather than requiring some voltage to switch on that device.

Forgive, I read your message to check between the connector and the PCB soldering point.

The early devices (until which s/n?) have no DC blocking capacitor, that's why I still suggest everybody is very careful when touching the connector. An inductor or surpressor diodes would help but the SBS-1e has exactly the same input stage and no such failures are known. That's why I suspect the problem has to do with earth/ground looping between the antenna, PC and mains.

It would be interesting if on devices that have been repaired a blocking capacitor has been added and whether these devices have failed again (seems to me that this has happened, from the above)

[nbquidditch]

Tarbat your absolutely right!!! I just checked both antenna's new & old and can see quite clearly that the pin in the orginal antenna has disappeared!!!

[tarbat]

Tarbat your absolutely right!!! I just checked both antenna's new & old and can see quite clearly that the pin in the orginal antenna has disappeared!!!

Glad it's sorted.   Maybe you can return the antenna you purchased for a refund.