Garmin 128 aerial broken?

[brownsox]

Having intermittent GPs probs decided it was the aerial. Top of mushroom will not shift so unscrewed whole mushroom which seems to have sheered off what looks like a thin coax cable inside. Is there any hope of repair? Can you get replacement aerials? We are in Sardinia which complicates matters. Any info advice v welcome. Thanks.

 

[Monique]

You should be able to replace. My aerial went out last year; expensive though as it includes all the processing functions in the mushroom.

GL

 

[VicMallows]

If there's enough stub of coax left to make any sort of connection you'll be OK. I routinely just twist the wires together or use a chocolate block on my 128 antenna. It's really not very critical.

Vic

 

[lw395]

You can buy gps aerials on ebay for about £10 or less. They are intended to work on a car roof or similar, so will need a metal plate about 200mm diameter to mount them on, this 'ground plane' is necessary to tune the antenna, but any dimension over about 150mm or will be OK. Might be worth removing the magnets that are meant to hold them on the car roof! You can always stick it on a paint can for a quick test, to show it works with the GPS.
A genuine Garmin or other marine antenna will be better, more waterproof etc, but will cost a lot more.
I used on of the cheap ones for a while on a GPS 120XL. I think the GPS128 needs a similar 'active antenna', i.e. an aerial with built in low noise amp, running off 5V supplied on the co-ax.

Some other Garmin mushrooms have the whole receiver in them and output data rather than amplified RF. These will have a multi-core connection instead of co-ax.

Look for an antenna with either a BNC plug to fit the garmin directly or an SMA plug so you can get a BNC/SMA adaptor.

 

[Vara]

To amplify on the "e-bay" aerials, both Navman plotters on boat are now driven by these, one was £4 the other £6.

I removed magnets, one is stuffed into binnacle and the other is taped to top of plotter at chart table.

Both have worked faultlessly for 5 months now.

On the chart table aerial, I dunked it into a glass of water for seven days and it showed no sign of water ingress or subsequent fault.(mind when in water it didn't pick up a signal.)

Have just tried adding a ground plane ( a steel oven tray) and it made no difference to signal.

I thought I'd replied to this post earlier today.

 

[cid]

Just a note to this tread. My 128 aerial seemed to be broken. It got knocked over and I was convinced that cable broken. Got a new compatible one on E-BAY, just under 10 euros. Then I decided to open the broken one.I used a hacksaw and worked along the grove between the bottom and top. Once I had broken through to the inside freshwater seeped out,( condensation). A quick blow of the hairdryer and it worked.I resealed and its back on boat working ok.(Lesson) If this happens to you drill a small hole into lower side of unit and let it dry out and see if it works.

 

[MASH]

My 128 antenna dome broke up after years of UV. All thats inside seems to be a square metal plate about an inch square - the antenna itself. It worked fine for a year or two topless and open to the weather. The dome is only for weatherproofing and aesthetics. You probably only need to open (cut/break) the dome and see how the antenna connects to the remains of the cable (and screening if any) and duplicate the attachment on the end of the cable you have left. GPS antennae aren't high tech at all and GPS' don't seem to be very fussy about their antennae either. You'll probably find just soldering the plate onto the end of the cable correctly and hanging it up somewhere naked will work fine until you get a replacement as suggested above.

 

[pvb]

The Garmin 128 uses a passive antenna - no electronics inside it. Any cheap generic GPS antenna should work.