Do I need gtn650 Nav antenna for initial powerup?

Desert Rat · #1 06-04-2022, 07:37 PM

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?

Walt · #2 06-04-2022, 07:53 PM

Nav antenna is not required for operation.

PilotjohnS · #3 06-04-2022, 07:57 PM

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.

Desert Rat · #4 06-04-2022, 08:23 PM

Thanks Walt, I was secretly hoping you would chime in

Desert Rat · #5 06-04-2022, 08:30 PM

Quote:

Originally Posted by PilotjohnS

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.

BobTurner · #6 06-04-2022, 08:32 PM

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.

BillL · #7 06-05-2022, 07:58 AM

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!

Walt · #8 06-05-2022, 08:24 AM

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.