Where to place filter

[LawrenceHill]

@Ruudjuhhh
See edit:

Where to place filter

The number of tracks with just a single message is really high. That would suggest you have a lot of noise on the signal into the dongle. What power supply are you using? Also how long is your antenna cable? You would achieve better results if you moved your preamp to the antenna end of your feeder cable. Edit: Maybe the single message rate is not that high after all. My main receiver is an Airspy mini and that shows virtually no single messages. However I have just reinstalled graphs on my P…

@SoNic67

As a general rule of thumb, the filters (insertion loss) should go after the preamp

This is where the general rule might not be applicable. It would appear that the preamp being used in this case, might be susceptible to overload, so placing the filter before the preamp might well be best.

Building a new receiver, this is going in a prime location - Suggestions for receiver/preamp/filter please

I totally agree. A big problem with the Uputronics LNA is the susceptibility to strong, nearby signals. 5W on 145MHz from our co-sited SSTV repeater would cause complete overload, dropping ADS-B signals down to zero within a second or so. The RTL-SDR-LNA doesn’t suffer from this - As can immediately be seen from the graphs.