Channel 16 Interference from GPS

redsnapper

redsnapper

Member
Joined
29 Apr 2005
Messages
36
Visit site
Last year I changed the GPS aerial to a raymarine Raystar 125 (The old one was broken). Ever since I have had interference on channel 16. I can turn up the squelch, but it that stops any transmissions. Strangely it doesn’t affect any other channels. The handheld VHF does the same thing. When I turn the GPS off, the problem goes. I have put on lots of suppression ferrites but this does not solve the problem. The radio is a Simrad RD68. Any help gratefully received.

Steve
 
redsnapper said:
Last year I changed the GPS aerial to a raymarine Raystar 125 (The old one was broken). Ever since I have had interference on channel 16. I can turn up the squelch, but it that stops any transmissions. Strangely it doesn’t affect any other channels. The handheld VHF does the same thing. When I turn the GPS off, the problem goes. I have put on lots of suppression ferrites but this does not solve the problem. The radio is a Simrad RD68. Any help gratefully received.

Steve
Click to expand...

Just a thought Steve but have you run cables adjacent to either power leads or antenna? You can sometimes get cross talk.
 
Could be...

I had a very similar experience after installing a new VHF; the tiller pilot interfered. These things are worth trying:

Run the GPS from an entirely seperate power source - a second battery or 12v power supply if you have shore power. That way you can check if the interference is along the DC supply. This is unlikely, though, because newer VHFs seem fairly impervious to routine supply probs.

Replace your VHF antenna with a temporary aerial, including feeder cable and plug. If you don't have a spare antenna, get a length of aerial cable with a plug already attached (unless you enjoy soldering PL259 plugs!), strip the insulation off about 18 inches, pull the inner insulation through the braided shield, stretch out and Lo! a half wave dipole (RF experts will jump on me, sorry, it's good enough for this test). Don't transmit using this, just listen to see if there's a change in the interference. If there is you might want to check your antenna installation. The shield (braid) integrity may be compromised, water in the connectors or joints etc.

The antenna did it for me, in fact I'm still using the 'temporary' solution strapped to the backstay, works fine.
 
Thanks. When I fitted the GPS I also fitted a battery monitor at the same time. The cable run is next to the GPS so will try that first. If not sounds like the aerial idea will be worth a try.
 
Any progress your end?

I have a furuno 2721 VHF which gets interference from the ST60 instruments - on ch16 from time to time, and to a much greater extent and permanently, ch00.
The noise contains the tick-tick of the echosounder as well as white noise, which disappear when the STs are powered off.
The interference seems to be airborne, as ferrites and capacitors don't fix, and the problem drops if the VHF antenna is unplugged.
I remade the braid connection at the set, which was a bit powdery, but it has not helped.
The VSWR is almost 1:1, and transmit tests are loud and clear at 12miles, so I don't suspect a coax problem.
A guess could be the VHF set is designed to be more sensitive on the two prime channels, but it is a most annoying bonus to live with if that is so.
Anyone else getting similar on any of their gear, and, any fixes?
 
Bill,

I have a similar setup - iCOM VHF, with ST60 Instruments communicating via (mainly) Seatalk (some NMEA in the mix). I don't experience any interference at all. This isn't helpful to you, but suggests that the problem is specific to your installation rather than generic.
 
I did get to the bottom of this. It was the wind transducer at the top of the mast. I changed the unit for a new one, and the problem disappeared. I think the bearings had gone, and was producing somthing that the VHF was picking up.

Rather expensive fix though!

Steve
 
You must log in or register to reply here.

Share this page

Top