Vhf/Gps dongle interference

[smithy]

Have just set up a laptop with seaclear and a maplin dongle. Vhf now has constant rythmical interference through it. If I remove the dongle it goes away. Handheld is not affected. Moving The laptop further away makes no difference. Any ideas?

 

[Oscar24]

Is the VHF experiencing interference a fixed set, i.e permanent 12v set for the boat with an external antenna ?
Does it use an external speaker unit?

I would check the location of the coax from this VHF set to the gps dongle unit. it may be a bit too close to the dongle and picking up some rfi, especially if the coax is poorly screened / old.

The fact that your hand held doesn't pick up the interference may be down to the hand held mute level being set higher than your other VHF set.

I would also try powering the laptop / dongle of its own battery. i.e not using the same battery as the VHF. Just in case the problem is power supply related.

 

[smithy]

Thanks for reply.
The vhf is fixed and has an external speaker although the interference is coming through both speakers, antenna is on top of the mast. The coax is fairly new and at least two feet from the dongle which has a very short lead into the laptop.
The laptop has no batteries and is powered from boats 12v using a universal charger. Will try using an inverter and standard charger and report back.

 

[maby]

certainly worth turning the squelch off on both the fixed and hand-held and checking for interference on both, It should be pretty much the same - possibly worse on the handie since it is going to have its antenna closer to the GPS adaptor than the fixed radio. If the interference is much worse on the fixed VHF, it does point towards something carried along the power lines rather than radiated. Try it with a laptop on its internal battery. You could also try getting two or three big ferrite rings or beads to clamp on the cable from the computer PSU to the boat's 12v supply - Maplins usually have a reasonable stock. They will go a long way towards blocking any interference.

 

[smithy]

Thanks
Will try on another laptop,with good batteries. If that makes a difference will try the ferrites. Can't alter the squelch on the handheld as its fixed. Will report back after weekend.