RTL-SDR with stock ADSB magnetic antenna and no filter
The answer is almost always yes anyway: Results are better with a filter.
This spectrum says filter like nothing else. FA filter for 10$ if you just get started 
One of the saw filters will cut interference much better of course but they are a tad more expensive except if you want to go with ebay from china and they can be hit and miss.
You might also want to consider building a Spider or Cantenna or at least cutting the mag mount antenna to size, there should be a thread about somewhere.
Well I already have 3 flight aware adsb filtersā¦I was just posting results in case anybody wanted to know how well the filter works
Sorry i just read the thread name and saw the spectrum you posted 
Anyway that is some strong signal you got there!
The spectra above were with the pro plus stick?
Must have clicked on your reply button by accident. Oh well.
Thanks for taking trouble of conducting raw scan on my request. It shows you have both GSM850 (very strong) and EGSM950 (moderate) cell phone signals in your area.
The raw scan (i.e. one without any filter and without any amplifier = generic dvbt only) gives a true picture of existing RF signals.
Switch to a SAW filter. The āworstā SAW filter Iāve seen still has a BW of 50 MHZ, +/- 25 MHz around the 1090 GHZ center frequency, which will take care of 950 MHZ interference.
The eBay $10 SAW filter may be an affordable solution, even when installing two, one before and another after the LNA/AMP.
Cheapest on ebay I found is $9.99 + $6 shipping = $15.99 say $16
EDIT:
Found one more $10.67 + Free shipping
Just one of many:
The first 2 spectrums & waterfalls were with the flight aware pro stick plus (blue one)ā¦the spectrum and waterfall I posted a few posts after that were a rtl-sdr dongle without any filter
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This is what i use. I found it very good, so I have ordered some PCBās and going to have a go at soldering some myself!
Hey Dxista, my rtl-sdr blog filtered LNA is in the mail and while it makes it way from china i was naturally checking out your stats as you mentioned you have one.
And iām wondering, are you limited by terrain or are there just no high flying aircraft in your 150 nmi range?
Or do you just cripple you range with all the other radio stuff you do 
My antenna is indoors, in the garage, with a southern view only.
I donāt think there is any interaction right now, but if it ever happens, hamradio will win everytime.
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I somehow knew that you are a prepper 
Not at all! Do you think Iām going to be underground, and miss the most fantastic pyrotechnical show ever?
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Thanks for all the great input - itās really appreciated.
This seem to be particulary true in my case so I need to do something
I read this thread and it did indeed make me more knowledgeable about filters - but it really is quite technical.
Also thanks for the explanation on filter chains.
This seems to be a great solution for me but I donāt really think the Bias T is my thing.
I have decided to go for this Uptronics 1090MHz ADS-B Filtered Preamp with USB power.
I also appreciate all the input about the more cheap SAW filters but I have decided to go for a filter/amp solution.
Thanks again to everyone for taking the time to chip in!
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So after reading this complete thread, and some others regarding filters and how to check what frequenties my antenna āreceivesā, I did a little test with the equipment I already have laying around.
I have got 2 setups:
1: a Jetvision black RTL dongle with magnetic mount whip antenna
2: a Flightaware Pro Stick plus with Flightaware outdoor antenna.
Setup 1:
Setup 2:
I upgraded a couple of months ago to the Flightaware dongle, and have the Flightaware antenna for 3 weeks, but I am somewhat surprised on how little the blue dongle filters out the unwanted frequenties.
However the amount of amplification of the ADS-B frequentie looks not to bad in my eyes and is fairly good.
Could anyone of you advise what kind of filter I should be using?
I do have cash to spend (I never have extra cash to spend, but hobbies may cost a bit 
).
So I have been thinking about a Jetvision 3 pole filter in combination with a Uputronics Ceramics filter.
However, I am still not really quite sure (due to my limited knowledge in regards to filters) what to would be better to have. Their ceramic version or the SAW version, as I havenāt really found a good comparison between the 2 (or my google powers are not good)
Thanks in advance!
I believe the rtl-sdr blog LNA is unbeatable for the money.
You are talking more expensive filters but i havenāt seen good comparisons of the system.
And you have to account for the fact that there is a high pass and 2 SAW filters in the LNA iām talking about.
Now the high pass will probably not attenuate the 900 MHz too much but the too SAW filters should each give 20dB.
Blue dongle has only a SAW filter.
I guess the ceramic filters give 60dB attenuation but their pass gap is quite a bit wider if i remember correctly.
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I use the Hab/Uputronics(Both ceramic and regular) Amp with the Jetvision 3 pole cavity filter. It works really well in my noisy environment.
I use them with a radarcape, Mode S Beast and the RTL-SDR dongles.
You could try just putting the Dongle in a metal case (and the RPI) to shield it from noise. This is a cheap step.
So is using Ferrite cores on the USB power cables and Dongle pigtail(if you use one).
The jetvision filter has a very narrow pass range. 10db at 1080Mhz, about 23db at 1065Mhz etc.