Nasa GPS to MLR2008 connection question


Active member
31 May 2001
I have a customer in France who writes to me thusly -

I have some trouble with my NASA GPS repeater. My GPS receiver is a MLR 2008 one with two wires DATA OUT + and - The repeater works with DATA OUT - , shows the position, the speed and cap but no destination (waypoint select on receiver). Is my connection correct ? MLR manual says to connect the two wires (DATA OUT + and -) from the receiver to the repeater ; but NASA repeater have only one DATA cable (blue one)! How can i do ? Best regards

Could anyone offer me advice for him?


New member
13 Apr 2005
Exeter, Devon
I have a similar problem with the same MLR2008 interfacing to a Navico TP20 Tillerpilot, can't remember the connections to the pilot but do know I gave up, guessing that the cable run from the chart table to the stern may have had something to do with it.....

If you get a solution to the repeater it maybe the same solution I seek?


New member
10 Sep 2004
If I understand you correctly, he is connecting the nmea -ve to nothing.

Surely the -ve line should go to gnd or put better the ships -12v line. That should make up his circuit.

Also, it is possible if he has the unit talking to quickly, lets say his GPS is talking at 9600 baud but the repeater only reads at 4800 baud the repeater will generally get the first sentence, but none of the others, they start at the same time but straight away go out of sinc. So he turns on and sees the lat and long, but then nothing else is received.

Of course as armchair diagnostics goes this could be well out.


New member
16 May 2001
I sent the following to another formite on a PM when he was asking a question about GPS connections

I have connected together a Garmin 128 GPS, a NASA clipper GPR repeater and an XM DSC VHF. I will try and describe in writing how they are connected.

The GPS also has the RS232 connector which is great because the NASA repeater also has the matching connector.

An important thing to remember is that the NMEA 0183 data is carried through a pair of wires.
<font color="red">
The two input wires to the XM DSC VHF are the yellow and green wires.

Essentially the yellow wire has to be connected to the NMEA out on the GPS this is the signal wire.

The green wire is the return wire and it must be connected to the common on the GPS.</font>

No other connection is required between the units other than making sure that they both have their supply etc.

This is how my units are connected together.

If the GPS has an RS232 socket and a NASA clipper repeater is used.

The GPS RS232 socket and Repeater RS232 plug are connected together.
<font color="blue">
Then the green XM VHF wire is connected to the central connection on the pcb mounted chocolate block at the rear of the repeater RS232 adaptor (labled ‘SCRN’ with black wire to it)

The Yellow wire is connected to the same chocolate block at the point labled ‘BLUE’ with blue wire on to it.</font>

The power etc is then applied to all the units.

John - The blue wire (labled BLUE) is the + and the black wire labled (SCRN) is the -ve.

I have highlighted the two relevent parts.

That should enable you to give your customer the correct answers.

BTW the two sets of blue towels are very good and arrived promptly thanks.