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Old 02-07-2018, 08:28 PM
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9GT 9GT is offline
Join Date: Jan 2010
Location: Southern Michigan
Posts: 1,520

Get a new BNC connector from Steinair and cut the cable. No need to have that much extra coiled up if you don't need it. I am not a wiz at electronics but had no problem installing the new connectors on my three G3X pucks I had mounted on a shelf under the cowling on my RV-10. My cheap coax crimper had the crimp die for it. I had no issues soldering the pins.
David C.
Howell, MI

RV-9A: Under Construction. N161RV (Reserved)
RV-10: N959RV Completed 12/29/2013 SOLD 08/23/2016

"Donor Exempt" but donated through Dec. 2018

Last edited by 9GT : 02-07-2018 at 08:35 PM.
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Old 02-08-2018, 10:23 AM
Ezburton Ezburton is offline
Join Date: May 2017
Location: MD
Posts: 39

Okay. Just coil it.

Thanks all for the input.
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Old 02-08-2018, 11:55 AM
Aluminum Aluminum is offline
Join Date: Jul 2017
Location: San Jose, CA
Posts: 193

Originally Posted by redbaron View Post
Garmin manual says to not cut the cable but coil it. Impedence issue
Cutting it won't change the impedance, but a poor crimp/solder will increase reflections, and a shorter cable will return more of them into the unit, increasing heat load. I'll venture a wild guess that the main concern here is with the longevity and reliability of the RF output electronics, not signal integrity.

Don't cut it; coil it.

EDIT: I just realized the OP was talking about the passive GPS *input* antenna, so the above is incorrect. Still applies to other RF cables so I'll leave it here for contemplation.
Dan V
'91 Zodiac flying since 2013
RV-14A in progress
2018 dues worth every penny

Last edited by Aluminum : 02-08-2018 at 11:58 AM.
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Old 02-08-2018, 01:22 PM
TrekLawler TrekLawler is offline
Join Date: Apr 2013
Location: Kansas City, MO.
Posts: 41

Hello everyone,
by no means is cutting the GPS antenna coax and simply splicing the cable back together a good idea, please do not do this without the proper tools or training to install a correct connector is only inviting degraded signal from the antenna.
The GPS antenna and extra coax length is designed so that the extra coax loss is of no concern when factoring system gains; if the coax is cut shorter and attempts to splice the connector end to this shorter cable end with solder and tape or shrink tubing then you're potentially reducing the 100% percent shielding effectiveness along with possibly creating an unknown impedance bump and possibly even a RF suckout that can result in acting like a notch filter all of which is unpredictable and could cause degraded operation of the system.

Please just coil it up and rig it in a safe fashion in the plane.
Trek Lawler
Supervisor, Aviation Field Service Engineering
Garmin International
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