How to get a Garmin GPS aerial apart to replace the coax?

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Gerry

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www.gerryantics.blogspot.com
The cable of my Garmin GPS 152 is damaged. I would like to take the aerial apart (it looks like a mushroom) so I can renew the coax wire without having connectors. The white plastic of the aerial is in two halves that look as thought they might unscrew - but don't.

Has anybody done this? Any suggestions?
 
Generally these are glues shut to make them waterproof. Some however are held together with a couple of small screws, are there any labels underneath that could be hiding some screws?

Ants
 
My mushroom unscrewed but did need a strap wrench and it had been well gunged with silicone rubber stuff. I can't remember if there was a grub screw - remove all tape(s) and make sure.
Keep the tails of the co-ax as short as possible when you solder.
 
Thank you for these tips.I have found a tiny black grub screw under a label, yet having removed it I still can't get the aerial apart even with strap wrenches. Any more force would probably crush the plastic.
 
The manufacturers issue dire warnings about joining GPS cables but it can be done. If you cannot get into the antenna then you can join a new cable or repair the existing one using high-quality (soldered) connectors. Make sure that you fully waterproof the connection once you've tested it.
 
Cable is nothing special .. Sometime they have a screen .. Trick is not to make it to long as the signal strength gets weaker the longer you make it .. You can cut the cable and fit a waterproof socket .. If the wires inside are very thin then you can solder them and use shrink wrap over the repair and then a larger one over all .. Using bluetack will help hold wires in place while soldering .. /forums/images/graemlins/smile.gif
 
Depends where the damage is... but we damaged our cable (headlining screw) mid length - cut at damaged section, strip - solder cores, insulate, solder screens and cover in self amalgamating tape - you will end up with a c90deg bend but it works fine. Alternatively you could use 50ohm BNC plug and socket to make the join. Obviously these methods wont work if its right up by the mushroom
 
Many thanks again. There is enough cable from the mushroom although the join will be external and exposed to the sea. So it looks like BNC connectors and loads of self-amalgamating tape.

Any tips on better weatherproofing? Silicon gel, perhaps? Lanoguard?
 
I can assure you there is really no problem joining he coax. I like to take the antenna off when I leave the boat on the mooring. After several types of connector just gave up when left unprotected, I just took to using a very crude twisted connection without even bothering to insulate. Hardly a constant-impedance joint I know .... but without doubt works!!

Vic
 
I have checked with the units I have in my engineering workshop and also checked with Garmin UK.

Sadly, these units are sealed for life and apart from breaking into the plastic and re-sealing with a plastic sealant, you will not be able to open the white dome to get at the co-axial cable. /forums/images/graemlins/frown.gif
 
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