VansAirForceForums  
Home > VansAirForceForums

- POSTING RULES
- Donate yearly (please).
- Advertise in here!

- Today's Posts | Insert Pics

  #1  
Old 02-07-2018, 06:08 AM
Ezburton Ezburton is offline
 
Join Date: May 2017
Location: MD
Posts: 35
Default G3X Touch GPS Antenna Length

Hi all,

I am finishing up the install of a dual G3X Touch and go to the point of routing the GPS antenna which plugs into the back of the display (GA-26C). The cable for the antenna is about 10ft long and I need about 1ft.

Has anyone cut out the middle 9 feet and spliced it back together? I imagine the wires are pretty small and they and the shields would need to be soldered. I hate to have a big coil of wire hanging around behind the panel.

Thanks,
Don
Reply With Quote
  #2  
Old 02-07-2018, 06:24 AM
Electrogunner Electrogunner is offline
 
Join Date: Aug 2016
Location: Quarryville ,pa
Posts: 296
Default Coax

Just cut to length and crimp on a new connector. Stein has the crimper and connectors and a video on how to install connector.
__________________
Donation Made For 2017
RV10 N620RV
IO540 C4B5
Whirlwind 375RV
Garmin G900X
Finishing and FWF is ongoing
Reply With Quote
  #3  
Old 02-07-2018, 07:01 AM
Walt's Avatar
Walt Walt is offline
 
Join Date: Aug 2005
Location: Dallas/Ft Worth, TX
Posts: 4,773
Default

I would just coil it up, installing those mini coax connectors is "challenging".
__________________
Walt Aronow, Dallas, TX (52F) RV7A, IO360, C/S, 1500+hrs

EXP Aircraft Services LLC
Specializing in RV Condition Inspections, Maintenance, Avionics Upgrades
Dynamic Prop Balancing, Pitot-Static Altmeter/Transponder Certification
FAA Certified Repair Station, AP/IA/FCC GROL, EAA Technical Counselor
Authorized Garmin G3X Dealer/Installer
RV7A built 2004, 1700+ hrs
Website: ExpAircraft.com, Email: walt@expaircraft.com, Cell: 972-746-5154
Reply With Quote
  #4  
Old 02-07-2018, 08:48 AM
Shawn25854 Shawn25854 is offline
 
Join Date: Aug 2014
Location: Clearwater, FL / KZPH
Posts: 125
Default

Before you cut it be sure it doesn't need to be a minimal length for a proper signal.

Shawn
Reply With Quote
  #5  
Old 02-07-2018, 12:56 PM
Rick_A's Avatar
Rick_A Rick_A is offline
 
Join Date: Oct 2005
Location: Highland Village, TX
Posts: 1,401
Default

Quote:
Originally Posted by Walt View Post
I would just coil it up, installing those mini coax connectors is "challenging".
If itís challenging for Walt, that means it next to impossible for us mere mortals.
__________________
Rick Aronow,
A&P, iRMT
Flying 7A Slider;
RV-12 (ELSA, Dual G3X), SOLD
Highland Village,TX
Reply With Quote
  #6  
Old 02-07-2018, 02:48 PM
redbaron redbaron is offline
 
Join Date: Aug 2013
Location: Lucerne,Ca
Posts: 226
Default Cable

Garmin manual says to not cut the cable but coil it. Impedence issue
Reply With Quote
  #7  
Old 02-07-2018, 03:00 PM
BobTurner BobTurner is online now
 
Join Date: Dec 2011
Location: Livermore, CA
Posts: 5,271
Default

Quote:
Originally Posted by redbaron View Post
Impedence issue
This is technically incorrect. The impedance of coaxial cable is independent of its length.
Reply With Quote
  #8  
Old 02-07-2018, 06:41 PM
Ezburton Ezburton is offline
 
Join Date: May 2017
Location: MD
Posts: 35
Default

I couldn't find anything about not cutting the antenna length in the install manual, just a lot about where to locate it (Section 22.1). Where did you see that?

I was thinking of reusing the mini coax connector... just cut the middle out of the cable and solder all the wires together and heat shrinking the whole thing.

Still not convinced this is an awful idea... but maybe it is something I can try after I get the plane put back together and back in the air.

Thanks
db

Quote:
Originally Posted by redbaron View Post
Garmin manual says to not cut the cable but coil it. Impedence issue
Reply With Quote
  #9  
Old 02-07-2018, 07:13 PM
rapid_ascent rapid_ascent is offline
 
Join Date: Mar 2008
Location: Dublin, CA
Posts: 918
Default

I don't think its a good idea to cut and re-solder. The impedance of the coax depends on have a continuous braid around the center conductor and the diameter of the center conductor. Both would have to be soldered and both would most likely be different than a unmodified section of coax. It would be nearly impossible to do and not effect the impedance. You will then create a discontinuity and the performance will be degraded.

As Bob mentioned the impedance isn't a function of the length of the cable. It has more to do with the relationship between the center conductor, the dielectric and the braid. However, the loss is a function of the length of the cable. I'm not sure if this is important or not in this application, only Garmin would know. If you were to shorten the cable it would be best to crimp on a new connector. With these smaller coax cables, and I haven't seen this specific cable this can be difficult to do correctly. I would suggest you just coil the coax as others have suggested since it will be hidden anyway.
__________________
Ray Tonks
2018 Donation Paid
RV-7 Fuselage in progress
* Rolled the Fuselage
RV-7 SB Wings
* Both Wings fully skinned
* Fuel Tanks Complete - No leaks finally
* Ailerons Complete
* Flaps Complete
RV-7 Empennage - Complete (a little fiberglass work left)
Vans Training Kit # 2 - Complete
Shop Setup - In Progress (Gathering Tools, Never Complete)
RV-7 Preview Plans
Vans Training Kit #1 - Complete
EAA Sheet Metal Class - Complete
Reply With Quote
  #10  
Old 02-07-2018, 07:15 PM
BobTurner BobTurner is online now
 
Join Date: Dec 2011
Location: Livermore, CA
Posts: 5,271
Default

Quote:
Originally Posted by Ezburton View Post

I was thinking of reusing the mini coax connector... just cut the middle out of the cable and solder all the wires together and heat shrinking the whole thing.

Still not convinced this is an awful idea... but maybe it is something I can try after I get the plane put back together and back in the air.

Thanks
db
This is a horrible idea. Even good connectors introduce some loss.
Edit: see Ray’s post for a more thourough explanation.
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -6. The time now is 02:51 PM.


The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.