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External
Since: Mar 24, 2004
Posts: 243
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(Msg. 1) Posted: Fri Feb 03, 2006 2:33 pm
Post subject: GPS Antenna Cable
Archived from groups: rec>boats>electronics (more info?)
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External
Since: Aug 07, 2004
Posts: 171
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(Msg. 2) Posted: Fri Feb 03, 2006 2:33 pm
Post subject: Re: GPS Antenna Cable [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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Butch Davis wrote:
> What are the ramifications of shortening the cable by cutting and spliceing?
> I've heard conflicting advice.
>
The GPS antenna cables are not "tuned" to length. A shorter cable
should give you less attenuation loss.
Meticulous work, attention to detail on cutting and trimming lengths,
careful soldering and crimping, all add up to good low loss cabling. In
recent years I started using a length of the adhesive lined shrink tube
about twice the length of the crimp sleeve over the sleeve and coax and
that really makes a nice sealed joint.
If you have to do a mid cable joint to accomplish a cable run, use
dielectic compound on it and seal it with heat shrink (use the non
adhesive if you think you want to get at it from time to time). You'll
lose about 1dB for each fitting, maybe 3dB for something like two BNC's
joined with a barrel.
Powered antennas will have a positive voltage on the center conductor
that is returned to ground via the shield. If you want to make sure
that is not inadvertently shunted to ground somewhere along the run, use
tape or shrink tube on any exposed connectors. You can usually use a VOM
on a coax connector to tell if an antenna is powered or not.
Not all powered antennas use the same voltage, it might be 3.3V or 5V in
my experience, I don't think I've never seen 12V on a GPS antenna though.
Jack
--
Jack Erbes in Ellsworth, Maine, USA - jackerbes at adelphia dot net
(also receiving email at jacker at midmaine.com) |
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External
Since: Jan 21, 2006
Posts: 26
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(Msg. 3) Posted: Fri Feb 03, 2006 8:20 pm
Post subject: Re: GPS Antenna Cable [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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I cut 2 meter off mine and gave it a new bnc plug. No problem.
It's a Garmin.
Bjarke
"Butch Davis" <butch1277.TakeThisOut@earthlink.net> wrote in message
news:YQJEf.5162$Nv2.4169@newsread1.news.atl.earthlink.net...
> What are the ramifications of shortening the cable by cutting and
> spliceing? I've heard conflicting advice.
>
> Thanks.
>
> Butch
> >> Stay informed about: GPS Antenna Cable |
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External
Since: Feb 26, 2005
Posts: 18
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(Msg. 4) Posted: Fri Feb 03, 2006 9:23 pm
Post subject: Re: GPS Antenna Cable [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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At 1575Mhz, the loss per connector is around .12db
"Jack Erbes" <jackerbes DeleteThis @adelphia.net> wrote in message
news:mcidnS-3k-Ek6X7eRVn-sQ@adelphia.com...
>You'll lose about 1dB for each fitting, maybe 3dB for something like two
>BNC's joined with a barrel.
> >> Stay informed about: GPS Antenna Cable |
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External
Since: Mar 24, 2004
Posts: 243
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(Msg. 5) Posted: Sat Feb 04, 2006 12:27 am
Post subject: Re: GPS Antenna Cable [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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Thank you, gentlemen.
The GPS I most want is unavailable, to date, with an internal antenna. The
external antenna will be mounted less than two feet from the receiver but
has about a thirty foot cable. I prefer not to have this cable wadded up
beneath my center console. Thanks to you, I believe I can safely shorten
the cable.
I'll double check with Lowrance but plan to do it unless it will void the
warranty.
Butch
"Bjarke Christensen" <BjarkeMC DeleteThis @grevestrand.de(nej, det skal selvfølgelig
være med K da jeg er dansker)> wrote in message
news:43e3ad1c$0$67264$157c6196@dreader2.cybercity.dk...
>I cut 2 meter off mine and gave it a new bnc plug. No problem.
>
> It's a Garmin.
>
> Bjarke
>
> "Butch Davis" <butch1277 DeleteThis @earthlink.net> wrote in message
> news:YQJEf.5162$Nv2.4169@newsread1.news.atl.earthlink.net...
>> What are the ramifications of shortening the cable by cutting and
>> spliceing? I've heard conflicting advice.
>>
>> Thanks.
>>
>> Butch
>>
>
> >> Stay informed about: GPS Antenna Cable |
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External
Since: Aug 07, 2004
Posts: 171
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(Msg. 6) Posted: Sat Feb 04, 2006 7:38 am
Post subject: Re: GPS Antenna Cable [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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Eric Fairbank wrote:
> At 1575Mhz, the loss per connector is around .12db
>
Really? I don't remember where I got that 1 dB figure, I think I got it
when I was installing 2.4GHz wireless systems. Or was the old Thicknet
network wiring? Boy was Thicknet a plumber's nightmare to work with.
I never measured it, just took what I heard at face value.
Jack
--
Jack Erbes in Ellsworth, Maine, USA - jackerbes at adelphia dot net
(also receiving email at jacker at midmaine.com) >> Stay informed about: GPS Antenna Cable |
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External
Since: Feb 26, 2005
Posts: 18
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(Msg. 7) Posted: Sat Feb 04, 2006 2:26 pm
Post subject: Re: GPS Antenna Cable [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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These myths of such high losses in connectors are plastered all over the
internet. It's one of the most common myths in amateur radio for example.
People are always claiming there's a 1 db loss per connector even at hf
frequencies when in fact it ranges from .005 at 3Mhz to .007 at 30Mhz.
Eric
"Jack Erbes" <jackerbes.DeleteThis@adelphia.net> wrote in message
news:IuGdnd7VeprWPXneRVn-qg@adelphia.com...
> Really? I don't remember where I got that 1 dB figure, I think I got it
> when I was installing 2.4GHz wireless systems. Or was the old Thicknet
> network wiring? Boy was Thicknet a plumber's nightmare to work with. >> Stay informed about: GPS Antenna Cable |
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External
Since: Dec 20, 2004
Posts: 22
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(Msg. 8) Posted: Sat Feb 04, 2006 3:27 pm
Post subject: Re: GPS Antenna Cable [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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My GPS 128 works well with its cable in a real state - was pulled out
of the BNC plug and I've just shoved it back in temporarily. I'll fix
it when I too shorten the cable. >> Stay informed about: GPS Antenna Cable |
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External
Since: Aug 07, 2004
Posts: 171
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(Msg. 9) Posted: Sat Feb 04, 2006 9:16 pm
Post subject: Re: GPS Antenna Cable [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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Eric Fairbank wrote:
> These myths of such high losses in connectors are plastered all over the
> internet. It's one of the most common myths in amateur radio for example.
> People are always claiming there's a 1 db loss per connector even at hf
> frequencies when in fact it ranges from .005 at 3Mhz to .007 at 30Mhz.
>
> Eric
Okay, thanks for the update, I'll never say that again.
Maybe the 1dB figure is the best case basis for the thoroughly inept
home hacker who heavily nicked the center conductor, then melted all the
insulation with a 100W soldering iron while also managing to get a cold
soldered joint on the contact, and has the whole mess covered with acid
core flux residue. :>)
Jack
--
Jack Erbes in Ellsworth, Maine, USA - jackerbes at adelphia dot net
(also receiving email at jacker at midmaine.com) >> Stay informed about: GPS Antenna Cable |
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External
Since: Mar 24, 2004
Posts: 243
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(Msg. 10) Posted: Sun Feb 05, 2006 12:04 am
Post subject: Re: GPS Antenna Cable [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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Thanks, Colin. That certainly simplfies the procedure.
Butch
<colinstone.DeleteThis@hotmail.com> wrote in message
news:1139095671.287112.63570@z14g2000cwz.googlegroups.com...
> My GPS 128 works well with its cable in a real state - was pulled out
> of the BNC plug and I've just shoved it back in temporarily. I'll fix
> it when I too shorten the cable.
> >> Stay informed about: GPS Antenna Cable |
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External
Since: Jun 30, 2004
Posts: 104
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(Msg. 11) Posted: Sun Feb 05, 2006 9:41 pm
Post subject: Re: GPS Antenna Cable [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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I have a Garmin 162 that came with an external antenna on an (IIRC) 25' cable. I e-mailed
Garmin asking if I could shorten the cable. They said no problem, but since we can't
be responsible for the quality of the connection, it will void the warantee on the antenna
(not the GPS). Since it was already out of warrantee, I shortened, and installed one of the
Shake CenterPin BNC connectors. Works fine, and I have a little bigger signal strength bars.
"Butch Davis" <butch1277.TakeThisOut@earthlink.net> wrote in message news:YQJEf.5162$Nv2.4169@newsread1.news.atl.earthlink.net...
> What are the ramifications of shortening the cable by cutting and spliceing? I've heard conflicting advice.
>
> Thanks.
>
> Butch
> >> Stay informed about: GPS Antenna Cable |
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External
Since: Aug 07, 2004
Posts: 171
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(Msg. 12) Posted: Mon Feb 06, 2006 11:29 am
Post subject: Re: GPS Antenna Cable [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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Chuck Tribolet wrote:
> I have a Garmin 162 that came with an external antenna on an (IIRC) 25' cable. I e-mailed
> Garmin asking if I could shorten the cable. They said no problem, but since we can't
> be responsible for the quality of the connection, it will void the warantee on the antenna
> (not the GPS). Since it was already out of warrantee, I shortened, and installed one of the
> Shake CenterPin BNC connectors. Works fine, and I have a little bigger signal strength bars.
>
So there is such a thing as a free lunch!
The attenuation on RG-58 is something like 1 dB per meter at 1,800MHz,
GPS freqs are in that general area. So depending on the quality of the
connector, the coax, and the length of the cut, I can see where there
would be some gain.
I'd stay away from the Radio Shack/Home Depot grade twist on connectors
though. :>)
Jack
--
Jack Erbes in Ellsworth, Maine, USA - jackerbes at adelphia dot net
(also receiving email at jacker at midmaine.com) >> Stay informed about: GPS Antenna Cable |
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External
Since: Mar 24, 2004
Posts: 243
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(Msg. 13) Posted: Mon Feb 06, 2006 2:53 pm
Post subject: Re: GPS Antenna Cable [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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Chuck,
Thanks. Good info!
Butch
"Chuck Tribolet" <triblet.DeleteThis@garlic.com> wrote in message
news:11udoca57vqlv43@corp.supernews.com...
>I have a Garmin 162 that came with an external antenna on an (IIRC) 25'
>cable. I e-mailed
> Garmin asking if I could shorten the cable. They said no problem, but
> since we can't
> be responsible for the quality of the connection, it will void the
> warantee on the antenna
> (not the GPS). Since it was already out of warrantee, I shortened, and
> installed one of the
> Shake CenterPin BNC connectors. Works fine, and I have a little bigger
> signal strength bars.
>
>
> "Butch Davis" <butch1277.DeleteThis@earthlink.net> wrote in message
> news:YQJEf.5162$Nv2.4169@newsread1.news.atl.earthlink.net...
>> What are the ramifications of shortening the cable by cutting and
>> spliceing? I've heard conflicting advice.
>>
>> Thanks.
>>
>> Butch
>>
>
> >> Stay informed about: GPS Antenna Cable |
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