Dont have rtl sdr v3 dongle, using external bias-t between generic dongle (dvb-t black) & LNA, as you can see in the photo
This is the result, i have seen that i have to keep changing the gain to have this at 5% strenght as you told in youâre guide.
Yeah that looks good.
My guess would be that you either have a bad cable or a bad connection.
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Can you unscrew the LNA and do another scan.
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Reattach the LNA but detach the antenna cable from the LNA, do another scan.
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Do a scan with the antenna cable connected directly to the dongle.
The scans donât need to be long, 5 minutes are plenty.
You can use this command line:
sudo rtl_power -f 900M:1150M:100k -i 30 -c 50% -e 5m -g 30 -F 9 >scan.csv
On further consideration, do scan number 3 first.
That one may be sufficient to tell further.
As you are now running without LNA, increase gain setting of dongle
That looks normal iâd say.
Not sure what the problem is then, somehow the LNA is not doing what it should.
Might be a bad LNA.
Are you sure you bought the filtered version and not maybe the unfiltered version by accident?
Without LNA filter cable connected straight to dongle, might need to change the gain iâm trying to test now with dongle and LNA but without cable and antenna
I did not bother to read the label carefully when I received it (fine print). After seeing your comments, checked carefully. Mine is tripple-filter
The non-filtered version doesnât have 1090 MHz or ADS-B printed on it either 
I have the same filter.
Probably something wrong with my filter, see result here: (dongle and LNA filter connected to pi but without the antenna and coax)
Yeah that shouldnât look like that. If you had switched input and output i would have expected it to not work at all, so pretty sure itâs a bad unit.
I guess your range/ message count is better even without the LNA? (probably at gain -10)
From one of my older posts, not sure which gain i used for the tests.
But it doesnât matter, it shouldnât look like your scan with a gain of 30.
Completed the comparison:
1: ProStick Plus without external filter
2: ProStick Plus with added FA filter
3: RTL-SDR BLOG V.3. with RTL-SDR BLOG LNAThe weaker signal at 1090 MHz for the ProStick Plus is not a shortcoming of that dongle, just different gain.
But even with higher gain at 1090 MHz the LNA combination shows its strength at eliminating virtually all out of band noise!
Yeah there is no mistaking it 
Could i have done something wrong during the activation of the bias t?
If it wouldnât be active then there should be no signal.
You can just test that by deactivating it and doing another scan.
Change to the directory you compiled it (cd ~/rtl_biast normally)
Run this to deactivate the bias-t:
./rtl-biast -b 0
Then do another scan, it should look different.
That setup needs really low gain, something like a gain of 5 or 10.
Also the power supply might be insufficient if you donât use a Official Raspberry Pi power supply.
If you are using an external LNA itâs best to use a dongle without amplification.
Iâd suggest you just try the uputronics where you just had the rtl-sdr LNA.
You can even power it via the bias-t without a problem so you donât even need to plugin USB for the uputronics.
Iâm still having the same problem, just did a test with the Uputronics Filtered Preamp
PI â RTL SDR V3, UPUTRONICS FILTERD PREAMP-> COAX ->JETVISION ANTENNA
But i still have some decent messages/sec
Did you make a scan with the bias-t switched off?
Iâd just turn off the v3 bias t and make sure itâs off in software.
Then supply the uputronics via USB.
Maybe itâs just the internal bias-t not working correctly.
Nevermind âŚ