Raymarine ST2000+ & VHF Interference

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exapp

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Hello,

A Raymarine ST2000+ that I fitted myself is causing interference on channel 16 on my VHF a Ray 49e. I fitted a suppression ferrite on the ST20000+ Data & power lines in various locations. (also affects my handheld VHF if held within 2m of tillerpilot)

Interference is along the lines of a buzz with a pulse. When holding the tiller pilot in my hand while electrically connected i can get the interference to vanish if I rotate in the horizontal and vertical planes.

Question is has any one had similar. I have had a few ST type autopilots and never had the same snag. Could it be a faulty unit.

ST2000+ is connected via seatalk back to a seatalk to nmea bridge. Bridge is connected to a Garmin GPSMAP3005c and ST60 instruments and VHF NMEA.

Regards,

Exapp.
 
Hi, I have just bought a ST2000, its going to be a couple more weeks until i fit the unit so will let you know. Raymarine recently had a problem supplying the ST1000 and ST2000, i did speak to them but couldn`t get a explanation as to why. Your best bet would be to talk to Raymarine, i am sure they can answer any technical problems.
 
I have had an ST2000+ for a couple of years, power in being the only wiring to/from it. It has never caused any interference to the VHF.
 
If the unit is in standby and you are getting bursts of noise, then it is most likely the seatalk/nmea signal on the wire causing it. If it only does it when in auto then it is motor noise.

Poor antennas, VHF cables running in the same trunking as the pilot and improper VHF grounding will make things worse.
 
Like i said it is causing interference in the handheld too so I dont' thinks its anything to do with how the fixed antenna or VHF is wired....
 
Not necessarily the case.

With the handheld you bring the aerial close to the autohelm so any tiny amount of noise picked up is going to be amplified.

With the fixed set the aerial is well away from the A/A so should be unaffected.

Worth checking condition of aerial lead, particularly the condition of the outer conductor connections.

If thats OK you are looking at the power side which poses the question of how does it affect the battery powered H/H?

Only other possibility that springs to mind is a problem on the NMEA i/f, possibly an earth loop.

If you disconnect the i/f from the VHF and the a/h and the noise disappears then this is probably the case.

If this happens perhaps post again and take it from there.
 
Hi, I've had a similar problem after doing re-wiring of my boat (see http://www.svsunnyspells.com/archives/ab...autopilot/77/).

It ended up being an earthing problem. I used the Seatalk cable to connect to a NMEA multiplexer and the NMEA input to connect to my chartplotter, both of which were earthed, but the primary power input negative (earth) was not connected (d'oh!). The resulting high currents on the signal earths for Seatalk and NMEA caused RFI which was picked up by the VHF antenna.

Many years ago I built an audio (hi-fi) amplifier which had earth loops because of multiple return paths to earth - the AC mains hum was unbearable! Fortunately I remembered that lesson.

Your best bet is to run all earths (and power supply grounds) to a single earthing point such as the main negative terminal on your electrical distribution panel.
 
Hello,
My old st2000+ had the same problem: loud noise on VHF channel 17 in cold conditions (156,85 MHz), and on channel 16 (156,80 MHz) when the pilot was getting hot.

Those pilots have a cheap ceramic oscillator to feed the processing unit with a 12 MHz clock signal.
12x13=156... it seems the 12MHz signal overtones combined with the "drifting" oscillatior's frequency are the cause of the problem.
Changing the oscillator (3 legged blue chip) solved it in my case.

The new autohelm PCB seems to come with a quartz oscillator, which is far more stable, but this PCB is around 280 euros. The oscillator chip is less than 1...
Hope this helps !

Regards,

Guillaume
 
exapp said:
Hello,

A Raymarine ST2000+ that I fitted myself is causing interference on channel 16 on my VHF a Ray 49e. I fitted a suppression ferrite on the ST20000+ Data & power lines in various locations. (also affects my handheld VHF if held within 2m of tillerpilot)

Interference is along the lines of a buzz with a pulse. When holding the tiller pilot in my hand while electrically connected i can get the interference to vanish if I rotate in the horizontal and vertical planes.

Question is has any one had similar. I have had a few ST type autopilots and never had the same snag. Could it be a faulty unit.

ST2000+ is connected via seatalk back to a seatalk to nmea bridge. Bridge is connected to a Garmin GPSMAP3005c and ST60 instruments and VHF NMEA.

Regards,

Exapp.
Click to expand...

I know this is a really old post but I'm wondering if you ever solved your problem. I have the exact same trouble. Intermittent interference only on ch16. If I move the TP I can make it come and go. Sometime days it works fine others it's on and off. I've re-done all electrical connections. cleaned the plug connectors. fitted a ferrite suppressor on the power lead but I've still got it. Anyone have anymore info about the oscillator chip?
 
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