Radio interference from GPS ??

[jimmy44]

Hi all.
I've just had a second hand 27mgz Uiniden radio fitted and a new Garmin178c GPS fitted by the same guy. Every time I turn on the GPS the radio squelches in time with what I think are signals from the GPS to the satelites. As soon as I switch off the GPS the interfernce stops. I cant "squelch out" the interference.
I've been told by Garmin to seperate both units and ariels as far as possible (bit hard with a centre console on a 17ft aluminium tinny) I did seperate both ariels and units by about 2.5 metres and tested. The same thing happened. I didn't have an ariel for the radio and the guy who fitted the units sold me one he had. Could it be the wrong type of ariel or would this make no difference ?

And one last thing. I'm reading in here that 27mgz is next useless and I need to go VHS but a mate has told me "nearly everyone " uses 27mgz so I'm confused. Or should I run both radios ? I'm brand new to offshore so this is all new to me.

Help please?

Jim

[station-rat]

Hi Jim
A 27 mhg radio will not give you a very big transmission distance. Are you sure that the 27 mhg is functioning correctly. Offshore i would go VHF, for greater transmission distance. If possible separate the 2 aerials about 3 meters and give it another try
Station-rat

[FNQCairns]

I have a garmin 5 series chart plotter and a VHF your problem is mine also, very poor of Garmin not shielding their head units well. I cannot squelch the interfearance away either, would not buy again for just this reason I own a boat they must have known that when they decided to save 50 cents per unit in manufacture.

cheers fnq

[Splash]

FNQ -

What does a head unit shield look like?

Splash

[FNQCairns]

A bit like a condom I think splash, nah I dunno simply a general term for designing equipment to a quality that it does not spill electromagnetic radiation out everywhere.

Mine is a GPS reciever it does 0 transmission yet it's the dirytest piece of passive electronics I have used on a boat-ever!

cheers fnq

[SatNav]

1. IS this 178C solely a GPS or GPS/Sounder?

2. I doubt if the "GPS" is actually causing your interference?

[jimmy44]

Thanks. It is a GPS, sounder,fishfinder the lot.

1. IS this 178C solely a GPS or GPS/Sounder?

2. I doubt if the "GPS" is actually causing your interference?

[FNQCairns]

Yesterday I moved the VHF aerial to the other side of the CC around 450mm now from the Garmin, still no good just a little better, take the VHF aerial away and the interearance drops to acceptable levels but the reception also drops:(. Or I can turn the GPS reciever off that works perfectly. The Furuno sounder is now 1 inch from the areial and no interfearance from it at all!

This Garmin is the most shitfull piece of noisy electronics ever, got the poops bad wouid like to ram it where it fits, never will I buy one of these low quality Garmin gpsmaps again.

Anyone who would like to buy it let me know.

[Dignity]

Wha about the power supply, is it running right next to the radio antennae cable, could be the culprit also. not withstanding crap shielding

[John Buoy]

For the sake of $10 try adding an inline noise filter to the radios power supply.

Available at repco/jayco/autobahn etc.

Regrads Frank

[Splash]

I am about to fit my new ICOM M504 unit with a 2.5m arial.

The holes that accomodated the previous 27Mhz radio are still there and next to the external GPS antenna.

Should I use these same holes for this new 2.5m VHF arial or should I place arial on other side of boat?

Should I have my ICOM unit near my GPS 292 and Furuno 585 or also other side of boat?

SPlash

[SatNav]

1. VHF has the capability of affecting GPS signals, not the other way around.

2. Keep any VHF aerial as far away as practical from a GPS antenna

[FNQCairns]

I am about to fit my new ICOM M504 unit with a 2.5m arial.

The holes that accomodated the previous 27Mhz radio are still there and next to the external GPS antenna.

Should I use these same holes for this new 2.5m VHF arial or should I place arial on other side of boat?

Should I have my ICOM unit near my GPS 292 and Furuno 585 or also other side of boat?

SPlash

Splash the low down on my 5 series is it has the new U beaut screen, I suspect this highly of being the problem, it's dirty electromagnetic radiation, spews lots out, the pops, highs and low hums follow the screen display to a T, a blacked out screen and all is quieter or while the unit is booting up.

I need 4/5 squelch on the VHF to block the noise which means the vhf is near useless, I can move the VHF aerial in real time away from the CC and it get much better until the cable lenght ends, or I can take the areial off and it is good also.

If yours uses the more typical screen display I suspect you will have no problem no matter how you do it,

The above is just my assumption so far from working through the problem in a systematic way. I also have a radio reciever capable of listening to VHF and the problem is there on that also. Hooking each unit up to their own induvidual separate and stand alone battery makes no difference, could also just have a dud, but no way of knowing without hooking up another identical head unit.

cheers fnq

[Splash]

Good Luck mate!

[Wyoming]

Your GPS is a reciever only and does not transmit, so I suspect that the noise you are experiencing over your Uniden is RF being generated by the power supply inside (or remote??) your GPS. To see if this is the case, try wrapping the GPS except the display, in Alfoil. If the noise goes, you know where to start looking...

[Simmo2]

May I go just a tad off topic, but in the same plane as Wyoming and others etc??
A plasma TV is just a receiver, how much RF noise do they generate???!!
SMS and LO's of electronic equipment nowadays is bullshit!
The sales of units that emit this crap far out weighs the people that buy equipment that cannot 'deal' with it.

However when units of similar calibre and with the same 'typical job' to do, ie a sounder with a big screen, and a VHF marine radio, are placed in close proximity (ie in a boat!) one would have thought that the issue could have been addressed by the manufacturer more closely.

If you have a remote screen, then perhaps a ferrite choke in the connecting cable could help?

[jimmy44]

Wha about the power supply, is it running right next to the radio antennae cable, could be the culprit also. not withstanding crap shielding


Yes it is running alongside the power supply. I will seperate them but thought technology was better than that these days. Thanks for your advice. I will let you know what happens.

[jimmy44]

Yesterday I moved the VHF aerial to the other side of the CC around 450mm now from the Garmin, still no good just a little better, take the VHF aerial away and the interearance drops to acceptable levels but the reception also drops:(. Or I can turn the GPS reciever off that works perfectly. The Furuno sounder is now 1 inch from the areial and no interfearance from it at all!

This Garmin is the most shitfull piece of noisy electronics ever, got the poops bad wouid like to ram it where it fits, never will I buy one of these low quality Garmin gpsmaps again.

Anyone who would like to buy it let me know.

I did a lot of research into GPS/ sounders before buying and Garmin came out as a clear leader in every way. Sorry to hear you are having so much trouble. If and when I get my noise fixed I'let you know how it was done. I intend running a VHF radio alongside the 27mgz so Who knows what will happen then ??

Jim

[imported_QCR]

FNQ,

I have the Garmin 525s and a Icom vhf. The radio ariel is mounted on the T-Top above the CC, It is only about 1.5 mtrs away and no problem at all. I do have all my electrics to each unit coming up on different side of the console so maybe that makes a difference

Terry

[frank100]

FNQ,
Try a "filter capacitor" across the supply to the gps (about 2,700ufds about $5 from Dick Smith if you have'nt got one, or one something around that value ie even a 1000ufds will do - carefull it will be polarised + to + and - to negative).

If this reduces the noise, a little better filtering of the supply should get rid of it altogether. Also if the noise is reduced it tends to confirm that the gps is actually transferring the interference through the power supply, which is most likely altough having said that electro magnetic radiation is possible (rf interference).

Frank

[Dignity]

Jim, what was the outcome

[polky]

FNQ I also have the 525s and I also have interference from GPS when I turn the am/fm radio on. Can you let me know if you have any sucess, I,ll be going to Dick Smiths on Saturday to see if they can help. Polky.

[John Buoy]

FNQ I also have the 525s and I also have interference from GPS when I turn the am/fm radio on. Can you let me know if you have any sucess, I,ll be going to Dick Smiths on Saturday to see if they can help. Polky.

Dick Smith here in Melb dont stock them
I found mine at Repco also Supercheap had them.
The filter worked for me with intereference problems on my Navman 6600
but just note that some of these filters have an inbuilt indicator light
which is always on So use your battery switch to shut the supply down
when not in use as it will drain your battery over a long period.

Frank