What is the cheapest way to replace my Raytheon RN300 GPS

[tudorsailor]

I bought a "pre-owned" 2001 yacht that is equipped with Raymarine/Raytheon kit. It has chart plotter, radar, autohelm etc. The GPS is Raytheon RN300 It is incredibly slow at getting a fix and sometimes takes 15 minutes to find 4 satellites. Sometimes I get no fix at all so do a reset and then a fix is quite quick. The software is V02.31. I am aware that the software should be v.4. However the Raymarine dealer in Palma could not do the upgrade and sent the unit to mainland Spain. They say they cannot do an upgrade and also the NMEA does not work (which it did before) They suggest spending 500 euros on an upgraded unit!

What are my options now? What is the cheapest way of replacing the RN300 (there is not one on eBay at present!)

Thanks

TudorDoc

 

[davel]

I had a similar problem when my Raytheon GPS receiver failed. Raymarine said it was irreparable but offered me a new one for about £250.
I bought a small SIRF GPS unit off eBay (about £15) and wired it into the NMEA port of my other Raymarine instruments. Works absolutely fine. It's inside the boat behind the instrument panel so is one less thing to wire up top !

 

[john_morris_uk]

I am sorry to hear that your RN300 isn't working. We are on our second (the first one went with our previous boat) and we have never had a moments problem with it. It fixes fast and gives a DGPS readout etc without any problem.

Have you checked the antenna and lead?

Have you tried sending it to Raymarine UK? Or Waypoint One in Plymouth are very good with Raymarine kit. They updated our software FOC a while ago.

 

[npf1]

I've got one of these too. I read on a website somewhere that they have an internal battery that, when it goes, causes the problem you mention. I'm pretty sure I kept the link somehwere so can I might be able to find it again. I seem to recall it said that the battery can be replaced.

 

[Talulah]

In my experience the issue will be with the aerial.
Buy a Raystar 125 GPS. Dispose with the old Raynav 300 GPS aerial. Connect Raystar 125 output to NMEA or Seatalk on Raynav300. Go through the Raynav 300 menus and set it to be a repeater.
You can then use the Raystar 125 output for other instruments as well.

 

[heard28]

I know it's an old thread but I've just been through the same process - RN300 very slow to get a fix, takes ages to build up signals from a decent number of satellites, and randomly loses fix and needs restarting from time to time. Given that the current Raystar replacement GPS needs the SeaTalk convertor to talk to my "old" ST60 instruments and RL70 series plotters, it was going to cost about £250 to go down the Raymarine route.

I bought a SirfStar 3 GPS for about £85 (always reluctant to say what I paid as someone else always says that they could get better for half what I paid...) with NMEA output. Doddle to install, given that the original boat wiring had a bit of choc block with the RN300 NMEA connections brought out to it. Even tucked up under the coachroof, it gets a good fix in less than 35sec from cold, will be using 7+ satellites in less than a minute, and is also receiving differential (EGNOS?) signals. I'll leave the old Raymarine antenna installed on the aft deck as it is the easiest way to fill the hole the cable goes through! RN300 easy to configure as NMEA repeater, and even repeats the NMEA input to its NMEA output which goes to the DSC radio.

 

[tudorsailor]

From where did you buy the SirfStar?

TS

 

[lw395]

Aerial is a likely candidate, as is any internal battery.
Also the self calibration of the carrier frequency can go out in old units, particularly if they are left switched off a lot or the internal battery is flat.
Leaving it powered up for several days can help with some units.
It may self calibrate over time.
Not sure if this applies to the Raymarine ones.
I improved an old GPS120 by tweaking the crystal to the frequency the receiver was expecting, but I was in a lab with a Rubidium reference and no work to do at the time.

You could get a ublox receiver module for 20 or 30 quid and stick it in the old box.

 

[heard28]

Aerial connection is certainly a possibility, although the fact that not touching the cable and just restarting the GPS fixes the problem suggests that it is not that probable. And the reported signal strength is well up - it's just that the RN300 doesn't seem to be able to get a position from the received signals.

I bought an Evermore SA-920 via Amazon. Evermore do a number of GPS boxes, and not all of them use the SirfStar 3 chip. You also need to watch out for the connection type - I used the NMEA/RS232 model, but there are USB and other options which would be less useful on a boat.

And, as predicted, someone has told me how I could have done it for less! Those Ublox modules look incredible for the price, although not quite as plug-and-play as the Evermore module. All the same, I did it for about one third the price of going down the Raymarine route.