Standard Horizon GX2200 - Noise from GPS

[Huntersailor]

I just discovered that while radioing with my GPS (Garmin) turned on the transmission has a loud buzz in it. The radio was just installed this year and normally I transmit to call our marina launch after the GPS is off. The transmission is clean on multiple channels with GPS off.

Any ideas on how to eliminate this issue? The choke on the DC supply is in place. The radio is in the cockpit and the GPS unit is in the cabin.

[GordMay]

Greetings and welcome aboard the CF, Huntersailor.

[River Cruiser]

I use SH electronic gear and have always had excellent tech service during my diy installation. Give them a call or send a email, I've used both and have always gotten a answer in a days time if using email.


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[fallingeggs]

Wish I could help as I have a GX2200 and an (older) Garmin unit, but I haven't experienced any problems. Agreed with the above about calling SH.

[Capt.Don]

Did you connect anything to the GPS or AIS out cables? If so, you might need to disconnect the ground.


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[ka4wja]

Huntersailor,
First off "loud buzzes" in your own transmissions are usually caused by a bad inverter / power supply....or ground loops...or bad ground wire connections...

But, how are you hearing them??
Or, is it just that others are reporting them??

Have you listened to your own radio, using another to receive your own signal??
And/or have you used SeaTow's Automated Radio Check System??



If you're referring to the SH GX2200, I believe it has a GPS built-in to it, yes???
Welcome to StandardHorizon.com

http://www.milltechmarine.com/custom..._EM044N170.pdf


So, I assume you have another "GPS" on-board, or perhaps a "chartplotter" / "MFD" (Multi Function Display)?? That might be the cause here...
BUT...

But, with a loud buzz in your transmit audio, I'm thinking this could also be caused by interference from a depth sounder (incorporated into a chartplotter / MFD ???)



And, usually this type of interference can be traced to bad wiring/connections, and/or a ground loop somewhere....especially if you've not connected a ground wire properly, from a NMEA cable, coaxial cable, etc...
(assume you have the GX2200 38400baud AIS output connected to your "GPS"???)

Originally Posted by Huntersailor

I just discovered that while radioing with my GPS (Garmin) turned on the transmission has a loud buzz in it. The radio was just installed this year and normally I transmit to call our marina launch after the GPS is off. The transmission is clean on multiple channels with GPS off.

Any ideas on how to eliminate this issue? The choke on the DC supply is in place. The radio is in the cockpit and the GPS unit is in the cabin.

My first thoughts for issues like this, with a new radio and new installation are typically bad wiring connections (including coaxial cable connections)...

Then, suspect wiring / connections to/from the plotter/MFD ('GPS")...
But, you haven't given us much info on what/how this Garmin GPS is, nor how it is wired/connected/networked (???)
So, it's tough to say anything specific...



Sorry, to be so brief this morning, but I've got an apt to get to.
If you can give us some more info, I'm sure we can help...


Fair winds...

John

[Huntersailor]

Thanks for your comments so far.

The GX2200 is totally isolated from the Garmin GPSMAP 740s chartplotter except for the DC power supply, fed from two separate circuit breakers. I have not connected any AIS or NMEA circuits between the two.

The buzz occurs without the boat engine running so there is no alternator interference. This occurs with only the DC battery as the power source and with ONLY the chartplotter on. No interference from any other equipment, including the Raymarine depth sounder, etc.

I may have to put an oscilloscope on the chartplotter power feed to see if it is feeding noise back on the DC line.

[Teknishn]

Possibly you have a power conflict between the two systems (Plotter and Radio). What I would try first would be to temporarily connect the SH Radio to the start battery (seperatng it from the house battery supplying the Plotter) and test again. If all good, look at your house battery. If not all good, you may have a problem with you radio and then contact SH. With that being said, are you using WiFi for Nav interface? WiFi is just another radio signal and may cause interference between system components. If so, turn off the WiFi and test the radio again.

[ve7mdl]

I have the same issue with a GPSMap 620 and the GX2200. I haven't had any reports on transmit, but on receive I get a buzzing or whining sound when using a headset. It looks like the GPSMap has a switching DC-DC voltage converter that causes the problem.

I partially solved the problem by adding a 470 microFarad capacitor on the power leads to the GPSMap. The whining is still there, but vastly diminished.

Cheers, ....Erik.
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