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.
- 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?