Have i missed something silly ?

Hi Folks,

I’m jut looking for a sanity check really…

Right now, I have two ads-b systems with antennas side by side (approx 1m apart) up on my roof.

The first (and troublesome one) is:
FA Antenna → N Plug 50cm 75ohm coax SMA-> uputronics pre-amp → SMA 50cm 75ohm coax N Plug-> N Socket 5m 50ohm Ecoflex coax N Plug → NtoSMA Adapter → rtlsdr v3 Dongle with Bias Tee for the amp → RPI3 (gain @ 49).

The second:
4 element homebrew CoCo → 6m 75ohm WF100 coax - FA Filter → FA Orange Dongle → RPI3 (gain @ 44.5).

In theory, the 1st setup should be outperforming the 2nd, due to the better antenna, pre-amp - proper cable for the main run etc… but it isnt… - it captures about 95% of the 2nd system.
Is it just that i have too many 50/75 ohm conversions - or is there something i’ve missed ?

Also worthy of note, I have run the gain scripts multiple times on both systems and the values shown have come out as optimal for each.

Any thoughts would be most appreciated.



My experience is that the FlightAware Pro Sticks easily outperformed a Nooelec Mini 2+ rtl-sdr dongle + external amp + external filter. The rtl-sdr.com dongle is probably better than the Nooelec but I’m still not surprised you get better results with the Pro Stick. Maybe the external amp has a much larger bandwidth than the LNA in the ProStick and it’s raising the whole noise floor.

After going from the Nooelec dongles to the FlightAware Pro Sticks, I’ve tried the combinations of with and without FlightAware filters on Pro Stick 1.0, 1.1, and Plus. The winner for me has been from a spider antenna directly into a Pro Stick 1.1 (orange) with no filter.

Also you might try swapping antennas and looking at the results. My location performs better with a spider antenna than with the FlightAware antenna, and I never successfully made a CoCo (I tried).

Thanks GDoggRaspberry - i’ll have to get back on the roof and have a play with various combinations…

I think you will see an improvement if you add an FA filter between your antenna and your Uptronics pre-amp.

I have the Uptronics with the ceramic bandpass filter and found that, in combination with the FA 1090 MHz filter, overall performance improved.

Thanks Chris, have moved my FA Filter in front of the Uputronics Amp - lets give that 24 hours and see what happens !


Keep us posted. :slight_smile: