My first post on this forum, just wanted to share a small success story.
I have just added an LNA and filter to my cheap set up (making it not so cheap).
And it has really increased my maximum range.
Initially i tried the components set up as Antenna → Filter → LNA → SDR but that didn’t work very well.
The reason i tried it that way was because i have a very high output broadcast FM radio tower just down the road from me and i thought it may have been saturating the SDR’s front end. I thought, filter first then amplify otherwise the LNA would also just get saturated with the out of band signal.
Then i changed it around to be Antenna → LNA → Filter → SDR i saw an instant improvement. I had the Raspberry Pi’s DUMP1090 web page running so i could see what planes it was picking up. Adding the LNA and filter doubled the number of planes on the map.
I am now getting planes up to 196 miles away in directions where heywhatsthat.com/ shows a theoretical maximum range of 214 miles.
Not bad for a $6 eBay antenna even if it is using about $70 of LNA and filter. 
I am still going to add a better antenna and mount it outdoors on the roof. It will be interesting to see if it delivers much more range.
It will definitely improve my directional coverage because the current indoor set up is blocked by the house for many directions.
Cheap $6 USD Magnet Base 1090Mhz Antenna (indoors at a 2nd floor window)
ebay.com.au/itm/201385878796
$35 USD PGA-103+ LNA
ebay.com.au/itm/111986803484
The guy that makes these was selling an LNA based on a different chip which had a Noise Figure of 2.6 dB. I sent him a message asking if he had looked at the PGA-103+ chip that has a Noise Figure of about 0.6 dB. He said he would have a look at them. I wasn’t expecting much but a week or two later he has a brand new LNA available based on the PGA-103+. Hows that for customer service.
$22.49 USD (+$12 shipping) ADS-B 1090MHz Band-pass SMA Filter from FlightAware
ebay.com.au/itm/141748987047
$19.95 USD RTL-SDR R820T2 RTL2832U 1PPM TCXO SMA Software Defined Radio
rtl-sdr.com/buy-rtl-sdr-dvb-t-dongles/
I recently bought the metal case for this unit but haven’t fitted it yet. It may help a little too.
Raspberry PI