FlightAware Discussions

Help Troubleshooting Sudden Drop Over 2 Hours

Hi, I’m relatively new, had an indoor 8 leg spider for a few weeks then just upgraded to outdoor antenna setup:
FA Antenna on roof
RTL LNA Filter
RTL-SDR Dongle
PiAware (not SD image)

For the last 24 hours, it was great, picking up aircraft from San Diego to LA. Then I noticed a precipitous drop. I was getting the same ADSB messages as my non amplified indoor antenna. Graphs1090 showed this gradual decrease starting around 930AM then a precipitous drop around 11AM. I was out of the house and made no changes at the time. I’ve checked all the connections, they’re fine. I rebooted the Raspberry Pi just before 1PM. I tried manually turning off and on the bias tee, no change. Any ideas?


So if you turn it off and nothing changes reception wise, that means the bias-t isn’t working or the LNA isn’t able to use the power.

A small extra power injector bias-t would be nice for testing.

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I bought another RTL-SDR V3 dongle, attached dongle to old LNA directly on the antenna, no change

I bought another RTL-SDR ADSB LNA, attached original dongle to new LNA directly on antenna, fixed problem immediately.

Moved the dongle and new LNA to enclosure, no longer working.

Moved the dongle and new LNA back to antenna, still not working.

Is my setup burning out the LNA? It’s RPi with POE hat, powered by hardwired LAN connection with standard POE.

You can see the narrow spike when I replaced the LNA, then afterwards when I moved it into the enclosure.

The enclosure is where my first LNA worked well for 36 hours then died (see previous post for graphs).


You got a new LNA and it died as well, that’s unfortunate.
I’m not sure why that would happen, no clue, sorry.

I bought two of those LNAs at the same time at the end of May. One worked fine and the other didn’t amplify the signal at all. Supplier replaced the faulty one and they’ve both worked fine since.

My understanding was that if the LNA was faulty, it wouldn’t pass any signal at all but that wasn’t what happened for me.

But I did have a weird episode where the system seemed to indicate that bias t was switched on but there was no signal at all. I checked the voltage and confirmed that it actually was off so I went though the installation of bias t again and it started working.

Maybe you are just extremely unlucky.

Bought a 3rd RTL-SDR ADSB LNA… problem fixed for now…