Raymarine AIS250 receive fault due to SSB?

[Goudurix]

I installed a Raymarine AIS250 in spring 2011, hooked into Raymarine C90W new GPS/chartplotter.
It worked well during the summer 2011, using the antenna splitter and using the masttop VHF antenna.
I did however remark interference on channels adjacent to both AIS frequencies (161.975 and 162.025 if I remeber well)on the marine VHF transceiver, so I installed a dedicated AIS receiving antenna on the pulpit.

During spring/summer 2012 a recureent problem emerged: after a while, this can be 10 mminutes but also after some hours, the AIS stops receiving data, giving erratic info on the plotter screen, sometimes phantom symbols or all AIS symbols disappearing.
The C90W plotter still sees the AIS250 as "active".
But on the AIS250 blackbox the red flickering led indicating ais data reception is out, not receiving anything, anytime the problem occurs.

CAUSE: SSB transceiver?
- I have a Yaesu FT897 in the navstation, linked to SGC-230 atu in the SB lazarette. The ATO antenna out lug is connected directly to the isolated through-hull connector to which the sloping wire antenna connects ubove deck
- the wire antenna is hoisted up the mast with a halyard on the SB side of the pulpit (so it is not an isolated backstay)
- the dedicated AIS RX antenna is standing on the port side of the pulpit, so its base is spaced about 3.0 metres from the wire antenna base
- if have a choking ferrite directly at the atu entrance - the coax+feedline bundle is wired 9 turns around a F240 type 31 toroid, to decouple, and this has very significantly reduced the panel lights "lightup"
- the AIS250 blackbox is installed about 0.4 metrs away from the FT-897 SSB in the navstation
- I have heavy clip-on ferrites on all wires arriving at the AIS250 (1 on the VHF coax, 1 on bith the FM radio antenna coax and data and power cables)

- the SSB is operated at good VSWR via the SGC-230 ATU


Could the problem still be caused by the SSB blowing part of the AIS-RX circuitry?

The AIS250 is now in for warranty servicing but I would like to avoid the same problem afterwards if suspicion on the SSB?

Jan
ON3ZTT

[Viking Sailor]

You could try a low-pass filter at the turner input to reduce the VHF harmonics from the transceiver. Another (obvious) possibility would be to move the AIS antenna farther from the HF antenna.

[Goudurix]

Thnx Viking sailor. Option 1 is feasible. Option 2 is one I would like to avoid...it would either mean getting back to use the masttop antenna with its flaw of interference on some VHF channels, or maybe move the dedictaed AIS RX antenna like on one of the spreader, with all the hassle of having to run the coax .....

To get back to the core of my question: do yo think it is possible that SSB spurious harmonics could have permanently destroyed some AIS receiver components, like maybe a preamp transistor? The strange thing is that it works sometimes, then stops. This is not occuring when working the SSB at the same time.

Jan

[monte]

Have you tried connecting your laptop to the AIS with a mini USB cable and running the Raymarine software? Mine stopped working for a while and I did that, changed a couple of settings and reset it and it worked fine since

[Goudurix]

Monte....interesting info. I did get a CD-Rom with the AIS250 but never bothered to look what's on it as it is more of a "plug and play" blackbox
Any clue on how to connect the AIS250 to a laptop with a mini USB cable? Can't remember there is a socket on the AIS250? I guess thhere is info on that on the CD-ROM (which I don't have at hand here in my office)

Anyhow it is in for servicing now with Raymarine, I will see how it returns and what happens when I use it again.

Thanks,

Jan