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Go Back   VAF Forums > Avionics / Interiors / Fiberglass > GPS
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  #1  
Old 06-04-2022, 07:37 PM
Desert Rat Desert Rat is offline
 
Join Date: Aug 2018
Location: Wichita KS
Posts: 1,048
Default Do I need gtn650 Nav antenna for initial powerup?

Like the title says.

I'm getting close to first power up and the wings aren't on so no archer antenna or cable hooked up yet.

I know that you can blow out a transmitter if you don't have an antenna hooked up, but what about the nav half of the GTN650?

I think the answer is no, since it's obviously receive only, But so far I haven't had any luck finding a answer in Garmin's zillion page manual.

Can anyone answer this question definitively?
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  #2  
Old 06-04-2022, 07:53 PM
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Walt Walt is offline
 
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Location: Dallas/Ft Worth, TX
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Default

Nav antenna is not required for operation.
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EXP Aircraft Services LLC
Specializing in RV Condition Inspections, Maintenance, Avionics Upgrades
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  #3  
Old 06-04-2022, 07:57 PM
PilotjohnS PilotjohnS is offline
 
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Location: Southwest, USA
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Default Careful

Although you asked a specific question be careful of the answer. Any transmitter antenna needs to be properly connected. other wise the radio can be damaged. You asked about navigation antenna, which really means VOR receive only, and the answer is correct.

It is best to have all antennas hooked up, lest one makes a mistake and blows up a $8000 Garmin box.
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WARNING! Information presented in this post is my opinion. All users of info have sole responsibility for determining accuracy or suitability for their use.

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  #4  
Old 06-04-2022, 08:23 PM
Desert Rat Desert Rat is offline
 
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Location: Wichita KS
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Default

Thanks Walt, I was secretly hoping you would chime in
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AGI, CFI, CFII, MEI, A&P, Janitor
RV7 Empennage & Wing done
Fuselage almost done
Avionics almost done
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  #5  
Old 06-04-2022, 08:30 PM
Desert Rat Desert Rat is offline
 
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Location: Wichita KS
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Default

Quote:
Originally Posted by PilotjohnS View Post
Although you asked a specific question be careful of the answer. Any transmitter antenna needs to be properly connected. other wise the radio can be damaged. You asked about navigation antenna, which really means VOR receive only, and the answer is correct.

It is best to have all antennas hooked up, lest one makes a mistake and blows up a $8000 Garmin box.
100% agree, but I'm going to have to opps check it sooner or later and I'd rather do it now before the fwd upper skin is on.
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Terry Shortt
AGI, CFI, CFII, MEI, A&P, Janitor
RV7 Empennage & Wing done
Fuselage almost done
Avionics almost done
90% done, 90% to go
#72651
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  #6  
Old 06-04-2022, 08:32 PM
BobTurner BobTurner is offline
 
Join Date: Dec 2011
Location: Livermore, CA
Posts: 8,523
Default

You can find dummy loads that have an BNC connector and can handle 5 or 10 watts, at least for short times. Just a suggestion.
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  #7  
Old 06-05-2022, 07:58 AM
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BillL BillL is offline
 
Join Date: Sep 2007
Location: Central IL
Posts: 6,838
Default I am ignorant of the electronics . . .but

The GPS puck gets 5 vdc (more or less) power from the single wire, and the AC/PWM signals ride on that, so might be sure the dummy is ok for the GPS side. As always, enlightenment invited from the experts.

Edit: Thanks Walt!
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Last edited by BillL : 06-05-2022 at 09:53 AM.
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  #8  
Old 06-05-2022, 08:24 AM
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Walt Walt is offline
 
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Location: Dallas/Ft Worth, TX
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Default

Wow so much ‘information’, you really don’t need any antenna connected to power up the GTN safely.
(Do not put a 50ohm dummy load on the GPS connector)!

The only precaution would be not to key the com, but even then, most coms are fully protected from transmitting into an open for short periods.

The only unit I’m familiar with (in GA) that can be damaged from no load on the antenna are mode S/ES transponders as they are very high power pulse units and are continuously outputting even when not being interrogated.
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Walt Aronow, DFW, TX (52F)

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, 2000+ hrs, New Titan IO-370, Bendix Mags, MTV-9 prop
Website: ExpAircraft.com, Email: walt@expaircraft.com, Cell: 972-746-5154

Last edited by Walt : 06-05-2022 at 08:31 AM.
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