FlightAware Discussions

Kuhne 1090 LNA

Hi there,

Back in 2008 I bought a Kuhne 1090 LNA and briefly fitted it at the mast top way back when I was using the original RadarBox hardware device.

Unfortunately it had the opposite effect of by actually reducing the amount of aircraft that I could see in MyFlights instead of the expected increase!

This I put down to the boosted signal overloading the front end of the RadarBox and so I reverted to feeding it from my external Watson Radar Extender via 5m of Westflex 103 directly into the RadarBox through an N-SMA adaptor.

Fast forward 12 years and I am now using a Raspberry Pi 4B and AIrNav FlightStick with the original antenna/cable and although I am pleased with my current Max Range of 295Nm and Avg Range of 219Nm located 150m ASL part of me wonders what the effect of the Kuhne might have these days when feeding this particular setup?

It could go one of two ways as I see it;

  1. As above where the boosted signal swamps the receivers front end as I also believe the FlightStick has its own LNA & filter built-in doesn’t it?

  2. If the receiver has become hardened through the years by better design, components etc. the extra signal strength could achieve its intended purpose by increasing the range and by definition the amount of aircraft I can see.

Does anybody have any experience or indeed theories about what adding the Kuhne might bring to the party?

I see from the Kuhne website that the current model is now called -2 so guessing that’s been redesigned/improved since my day although I don’t know what the differences might be?

Thanks & kind regards,

My guess would be that it wouldn’t make things worse and should improve it if you’re not already at your terrain limits.

Out of band signals are much more likely to overload the LNA than the actual signals on 1090.
Avoiding SDR overload can be achieved by reducing the gain.

Other people have added 27 dB of amplification to the FA blue stick and had good results. (kinda surprising to me, 27 dB as in the triple filtered rtl-sdr LNA)
For the RB green stick i’m not 100% sure.

If you have such rather expensive gear you could always get an rtl-sdr v3 SDR or even AirspyMini to use with the Kuhne 1090 LNA, both of those won’t get overloaded for sure when adjusting the gain correctly.

Thanks for taking the time to reply wiedehopf,

Well if the rtf-sdr v3 or AirspyMini will do a better job than my AirNav FlightStick then I will definitely take a look…

I was asking about gain in another thread…

Thanks & kind regards,

The airspy will do better, the v3 … might do better might do the same.
Without a filtered LNA they will both do worse than the RB green stick.
It’s a bit more complicated you see :wink:

Ah anything Pi is always complicated for me wiedehopf! :grinning_face_with_smiling_eyes:

My interest is piqued by the Airspy Mini (and maybe its bigger brother the R2) but I wonder if you or anybody can tell me if I went with the Mini would it be as simple as just unplugging the AirNav FlightStick and plugging in the Mini with no software changes etc?

Apart from reconnecting the antenna of course!

That might make my decision easier…

I’m guessing it should just be Plug&Play as typing the command; sudo systemctl status dump1090-fa returns;

● dump1090-fa.service - dump1090 ADS-B receiver (FlightAware customization)
Loaded: loaded (/lib/systemd/system/dump1090-fa.service; enabled; vendor pres
Active: active (running) since Thu 2020-12-17 12:38:06 GMT; 9min ago
Docs: https://flightaware.com/adsb/piaware/
Main PID: 486 (dump1090-fa)
Tasks: 3 (limit: 4915)
CGroup: /system.slice/dump1090-fa.service
└─486 /usr/bin/dump1090-fa --device-index 0 --gain -10 --ppm 0 --max-

Dec 17 12:38:06 RaspberryPi-air systemd[1]: Started dump1090 ADS-B receiver (Fli
Dec 17 12:38:07 RaspberryPi-air dump1090-fa[486]: Thu Dec 17 12:38:07 2020 GMT
Dec 17 12:38:07 RaspberryPi-air dump1090-fa[486]: rtlsdr: using device #0: Gener
Dec 17 12:38:07 RaspberryPi-air dump1090-fa[486]: Found Rafael Micro R820T tuner
Dec 17 12:38:07 RaspberryPi-air dump1090-fa[486]: rtlsdr: enabling tuner AGC
Dec 17 12:38:07 RaspberryPi-air dump1090-fa[486]: Allocating 4 zero-copy buffers

So the AirSpy looks to be the same Rafael Micro R820T tuner as the existing AirNav as reported above.

Logic sort of tells me a $99 device should perform better than a $25 device but of course this is no guarantee.

Thanks & kind regards,

No it requires its own decoder software in addition to dump1090-fa/readsb.

It mentions airspy mini and that configuration script requires dump1090-fa or readsb.

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