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15-07-2022, 13:02
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#1
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Registered User
Join Date: Sep 2008
Location: Auckland, NZ
Boat: Hood 38 - Wauquiez
Posts: 738
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Replace Male SMA on GPS antenna
Has anyone tried to replace a male SMA connector on a GPS antenna wire?
I suspect the center conductor has broken, and I am crossing fingers that its broken near the existing connector. I have a bit of surplus length so I can re terminate.
The wire itself is not the usual 8mm or so thick coax, this GPS antenna wire is more like 3mm wide (very thin) and black in color. Never tried one that thin.
Is there a way to test the cable and see how far down the wire the break is?
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15-07-2022, 14:46
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#2
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Registered User
Join Date: Mar 2014
Location: Atlantic Ocean
Boat: Tayana 48DS 48'
Posts: 380
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Re: Replace Male SMA on GPS antenna
3mm sounds like RG-174 cable - you can buy connectors for this cable online though most connectors for this size cable require a properly-sized crimp tool. I would think NZ would have a supply house for this sort of thing.
There is an instrument that can tell where a break is - its called a time-domain reflectometer (TDR), and while lab-grade versions are extremely expensive, if you know someone who has an instrument called a "NanoVNA", this can be configured to work as a TDR. For you, it would be cheaper to replace the cable and connector rather than acquire one, but they are useful for many other antenna and feedline checks, so "radio guys" tend to have them around.
Hope this helps!
Hartley
S/V Atsa
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15-07-2022, 14:54
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#3
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Registered User
Join Date: Sep 2008
Location: Auckland, NZ
Boat: Hood 38 - Wauquiez
Posts: 738
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Re: Replace Male SMA on GPS antenna
Awsome answer - thanks.
The cable (now that I am on the boat) is ECE R118. Long story but since the other end is sealed and hardwired I am really looking to replace the connector.
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15-07-2022, 15:21
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#4
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Moderator and Certifiable Refitter
Join Date: Jan 2008
Location: South of 43 S, Australia
Boat: C.L.O.D.
Posts: 21,277
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Re: Replace Male SMA on GPS antenna
Breaks usually occur just where the coax exits the connector. In absence of any external visual damage elsewhere, cut a few inches off the end of the coax (assuming you have enough to work with) and fit a new SMA connector. SMA connectors are available in crimp and solder/clamp styles. For a one off, the solder/clamp is probably more convenient unless you have access to the correct crimping tool.
You will need good eyesight.
__________________
All men dream: but not equally. Those who dream by night in the dusty recesses of their minds wake in the day to find it was vanity: but the dreamers of the day are dangereous men, for they may act their dreams with open eyes, to make it possible. T.E. Lawrence
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15-07-2022, 15:26
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#5
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Registered User
Join Date: Sep 2008
Location: Auckland, NZ
Boat: Hood 38 - Wauquiez
Posts: 738
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Re: Replace Male SMA on GPS antenna
Quote:
Originally Posted by Wotname
Breaks usually occur just where the coax exits the connector. In absence of any external visual damage elsewhere, cut a few inches off the end of the coax (assuming you have enough to work with) and fit a new SMA connector. SMA connectors are available in crimp and solder/clamp styles. For a one off, the solder/clamp is probably more convenient unless you have access to the correct crimping tool.
You will need good eyesight.
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Agreed - and thats where I hope the break is - yes I have surplus cable. I am now trying to identify the correct SMA for the cable size. (2.8mm dia OD)
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15-07-2022, 15:47
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#6
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Registered User
Join Date: Mar 2014
Location: Atlantic Ocean
Boat: Tayana 48DS 48'
Posts: 380
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Re: Replace Male SMA on GPS antenna
ECE R118 is not a cable size, unfortunately - its a European fire-retardance spec.
But RG-174 has an OD of 2.79mm, so I'm sure thats what you have!
Hartley
S/V Atsa
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15-07-2022, 16:46
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#7
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Moderator and Certifiable Refitter
Join Date: Jan 2008
Location: South of 43 S, Australia
Boat: C.L.O.D.
Posts: 21,277
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Re: Replace Male SMA on GPS antenna
Yes, almost 100% sure it will be RG-174.
An SMA suitable for RG-174 will be OK even if the cable is slightly different to RG-174.
__________________
All men dream: but not equally. Those who dream by night in the dusty recesses of their minds wake in the day to find it was vanity: but the dreamers of the day are dangereous men, for they may act their dreams with open eyes, to make it possible. T.E. Lawrence
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15-07-2022, 18:00
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#8
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Registered User
Join Date: Sep 2008
Location: Auckland, NZ
Boat: Hood 38 - Wauquiez
Posts: 738
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Re: Replace Male SMA on GPS antenna
Thanks guys.
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17-07-2022, 23:01
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#9
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Registered User
Join Date: Sep 2008
Location: Auckland, NZ
Boat: Hood 38 - Wauquiez
Posts: 738
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Re: Replace Male SMA on GPS antenna
Quote:
Originally Posted by Wotname
Breaks usually occur just where the coax exits the connector. In absence of any external visual damage elsewhere, cut a few inches off the end of the coax (assuming you have enough to work with) and fit a new SMA connector. SMA connectors are available in crimp and solder/clamp styles. For a one off, the solder/clamp is probably more convenient unless you have access to the correct crimping tool.
You will need good eyesight.
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Replaced SMA - and we are back in business. Thanks guys.
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17-07-2022, 23:48
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#10
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Moderator and Certifiable Refitter
Join Date: Jan 2008
Location: South of 43 S, Australia
Boat: C.L.O.D.
Posts: 21,277
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Re: Replace Male SMA on GPS antenna
Thanks for the update, it is always good to hear how these things work out in the end!
Well done for solving it -
__________________
All men dream: but not equally. Those who dream by night in the dusty recesses of their minds wake in the day to find it was vanity: but the dreamers of the day are dangereous men, for they may act their dreams with open eyes, to make it possible. T.E. Lawrence
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30-07-2022, 02:01
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#11
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Registered User
Join Date: Sep 2008
Location: Auckland, NZ
Boat: Hood 38 - Wauquiez
Posts: 738
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Re: Replace Male SMA on GPS antenna
Spoke to soon - the GPS crapped out again today. I have nothing to loose now by chopping the GPS antenna cable near where it comes out of the puck, attaching a female connector and then replacing the rest of the cable run.
Has anybody done this before and had it work? I am tempted to replace RG174 with RG58 - but thoughts?
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30-07-2022, 02:33
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#12
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Moderator and Certifiable Refitter
Join Date: Jan 2008
Location: South of 43 S, Australia
Boat: C.L.O.D.
Posts: 21,277
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Re: Replace Male SMA on GPS antenna
You haven't told us how long the coax run is but if it is greater than say 6', then RG174 is a poor choice. 1 or 2 feet is OK.
RG174 has about 2.5 to 3 times the loss of RG58.
__________________
All men dream: but not equally. Those who dream by night in the dusty recesses of their minds wake in the day to find it was vanity: but the dreamers of the day are dangereous men, for they may act their dreams with open eyes, to make it possible. T.E. Lawrence
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30-07-2022, 02:52
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#13
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Registered User
Join Date: Sep 2008
Location: Auckland, NZ
Boat: Hood 38 - Wauquiez
Posts: 738
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Re: Replace Male SMA on GPS antenna
Quote:
Originally Posted by Wotname
You haven't told us how long the coax run is but if it is greater than say 6', then RG174 is a poor choice. 1 or 2 feet is OK.
RG174 has about 2.5 to 3 times the loss of RG58.
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The antenna puck came with 5m (yes meters!!!) of RG174. I am tempted to replace with RG58 for the reason you gave - I was surprised they used RG174.....I actually don't need a 5m run either. I can probably get away with 4m - its been trimmed to that length anyway as a result of me replacing the SMA connectors.
Will the additional connection just after the puck not result in too much loss?
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30-07-2022, 04:20
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#14
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Moderator and Certifiable Refitter
Join Date: Jan 2008
Location: South of 43 S, Australia
Boat: C.L.O.D.
Posts: 21,277
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Re: Replace Male SMA on GPS antenna
The lower loss of the RG58 will more than make up for the connector loss.
__________________
All men dream: but not equally. Those who dream by night in the dusty recesses of their minds wake in the day to find it was vanity: but the dreamers of the day are dangereous men, for they may act their dreams with open eyes, to make it possible. T.E. Lawrence
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30-07-2022, 13:09
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#15
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Registered User
Join Date: Sep 2008
Location: Auckland, NZ
Boat: Hood 38 - Wauquiez
Posts: 738
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Re: Replace Male SMA on GPS antenna
Quote:
Originally Posted by Wotname
The lower loss of the RG58 will more than make up for the connector loss.
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Good to know. Thanks for your input. Hoping that this fault, which is very intermittent is somewhere in the cable and not the antenna. After my last repair I certainly "detect" lots of satellites, just perhaps the signal is not strong enough for a fix. I also wondered about whether the cable being routed through the stainless steel radar arch poles next to the solar wiring was the issue, but even when outside the radar arch the issue persisted.
The join maybe exposed to the elements, so I was just going to coat it in a generous blob of sika flex unless there is a more elegant way.
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