GPS Antenna

[BobnLesley]

I would’ve tried Googling this, but as I’m on a very expensive and slow/flaky Wifi connection, so I am hoping someone here will have the answers:
We have a Garmin 128 Fixed GPS Unit that we really like, but it’s just become erratic with regard to finding itself; as the problem’s especially prevalent on wet days we’re suspecting that the antenna’s cable is past its best – it certainly looks to be tired/UV damaged.
So, is it feasible/practical to disconnect and just renew the cable – my understanding is that a precise cable-length is vital to accurate operation? – and if so, what type of cable will I need to use? If this is not practicable, where should I look to source a new antenna? Are they all the same or will it be a unit that’s specific to Garmin GPSs and perhaps even to the 128 model too?

 

[Davy_S]

http://www.ybw.com/forums/showthread.php?247122-Garmin-128-aerial-brokenhttp://www.ybw.com/forums/showthread.php?247122-Garmin-128-aerial-broken

 

[prv]

I bought a second-hand 128 that came without an antenna. I bought an antenna for a few pounds on eBay, which listed the 128 as one of the units it was compatible with. I had some initial bother getting the GPS working (there's a thread on here from a few months ago) but that was due to the unit being unpowered for a long time and forgetting all its satellite data. Once I left it with a good view of the sky for long enough it started working. Nothing to do with the antenna, which also worked immediately when tested on a second GPS.

The antenna was much smaller than the original, black, and I'm not sure if it was waterproof. So rather than mounting it on deck I'm going to glue it to the underneath of the side deck, inside the space behind the chart table. I expect it to work fine through the fibreglass.

Pete

 

[pagoda]

I would’ve tried Googling this, but as I’m on a very expensive and slow/flaky Wifi connection, so I am hoping someone here will have the answers:
We have a Garmin 128 Fixed GPS Unit that we really like, but it’s just become erratic with regard to finding itself; as the problem’s especially prevalent on wet days we’re suspecting that the antenna’s cable is past its best – it certainly looks to be tired/UV damaged.
So, is it feasible/practical to disconnect and just renew the cable – my understanding is that a precise cable-length is vital to accurate operation? – and if so, what type of cable will I need to use? If this is not practicable, where should I look to source a new antenna? Are they all the same or will it be a unit that’s specific to Garmin GPSs and perhaps even to the 128 model too?

Try "garmin gps 128 antenna" in Ebay. Lots of quite inexpensive alternatives to official Garmin kit.

Most GPS systems with external antennas use active antennas. 3 or 5V DC supplied up the cable to power a pre-amplifier of a couple of transistors in the antenna itself. I would seriously doubt you need to buy the real thing (at Garmin prices)

Graeme

 

[prv]

I would seriously doubt you need to buy the real thing (at Garmin prices)

I would seriously doubt that you can . New, anyway.

I like the GPS128, to the point of trawling ebay for one to install on our new boat which already has a Raymarine GPS and plotter, but by now it's a seriously obsolete piece of kit.

Pete

 

[Vara]

For my Navman went down the cheapy eBay route, works perfectly for £3.99 iirc, bought two

 

[VicMallows]

my understanding is that a precise cable-length is vital to accurate operation? – and if so, what type of cable will I need to use?

The length is unimportant, and the coax type is not critical. (the signal frequency between antenna and 128 is quite low and the strength quite high). I would at least try chopping the coax a foot or so from the antenna and trying a temporary length of coax. Twisted connections will be adequate for a test.

Beyond that it's a case of opening up the antenna, which will be semi destructive.

 

[Ex-SolentBoy]

When you get your new one don't bother installing it outside. Hide it inside the boat. They work just as well there.

 

[BobnLesley]

Thanks for that folks, you've never failed me yet!

I've got some co-ax VHF cable stowed aboard somewhere so we'll give that a try in the short-term (we're in Suriname, which isn't noted for it yachting-supplies industry) and go the ebay route once we get up to the Caribbean.

 

[duncan99210]

Thanks for that folks, you've never failed me yet!

I've got some co-ax VHF cable stowed aboard somewhere so we'll give that a try in the short-term (we're in Suriname, which isn't noted for it yachting-supplies industry) and go the ebay route once we get up to the Caribbean.

If you can find it.......

 

[lustyd]

In case it's helpful, an old thread about replacing the soldered on battery with a battery holder is at http://www.ybw.com/forums/showthread.php?286132-Instructions-for-replacing-a-Garmin-GPSMap-235-battery-%28PICS%29. although for a different unit I believe they generally are the same inside.

 

[lenseman]

I would’ve tried Googling this, but as I’m on a very expensive and slow/flaky Wifi connection, so I am hoping someone here will have the answers:
We have a Garmin 128 Fixed GPS Unit that we really like, but it’s just become erratic with regard to finding itself; . . . . .

I would leave it a couple of days and re check as there has been a large CME (15 March 2013) and this could be effecting how your equipment is receiving the GPS signal?

http://thewatchers.adorraeli.com/20...1-2-solar-flare-full-halo-earth-directed-cme/

"A 10cm Radio Burst was associated with the event indicating significant radio noise in association with a solar flare. This noise is generally short-lived but can cause interference for sensitive receivers including radar, GPS, and satellite communications. Region 1692 was still classified with Alpha magnetic configuration at 0:30 UTC today."



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