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Full Version: [DG] Autohelm interface w RC425
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Hi I have an old Autohelm 1000 that I would like to interface with my RC425 chartplotter. I see it has a four pin outlet at the back, which I think is a Seatalk. Do I really need the interface box or is NMEA 0183 coming out of there? If you could provide me with a plug or the schematic of the pins I would appreciate it.
On a side note, I received tech support from "Underway" once in the past for my X5 and he was a lifesaver. Thanks.
Hi John,

Thank you for your enquiry.

The older Autohelm 1000 with a 4 pin plug on the underside was pre SeaTalk and the only way to connect NMEA to it is via an interface box, part number Z075. This was called the Radio navigation interface, was 4" square and had a rotary knob on the front as well as a red and a green LED.

[Image: attachment.php?aid=2300]

I think I should clarify, that the Autohelm 1000 is a tillerpilot.
It appears that the "radio" box in the photo might be for a motorboat? So no NMEA 0183 data comes out of the ST 1000 tillerpilot?
Hi John,

The interface box in the photograph was used to connect the cockpit autopilots to an NMEA source, so was mainly used on sailing boats, but work equally well on motor boats if required. The speed selector control was used to help adjust the gain of the system for faster boats.

You previously advised that you had an Autohelm 1000 - in which case, it cannot receive NMEA0183, the ST1000 - the later model also did not receive NMEA0183, only SeaTalk. The current ST1000+ receives NMEA0183 direct.

So I have managed to dig up a "clone" schematic for a Z075 Radio navigation interface. Seems like a challenge to find discrete components these days, but the real challenge would be to sort out "IC2" referred to as a 2RNA... I expect it is a microprocessor that issues relay commands deciphered from the 0183 data stream. Maybe it is really an Arduino raspberry-pi type of project?

Dear Joseph Owens,

Thank you for your post. We no longer have any of the electronic components for this product and any drawings we had are long gone, on this occasion we cannot help.

Many Thanks
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