I think my RTL-SDR triple filtered LNA died.
There was a large drop in signal a few days ago. The internal power light was still on.
Swapped out the RTL-SDR triple filtered for an Uputronics around 6:10 on this graph
That’s unfortunate as they aren’t available anymore. On the rtl-sdr blog they say they are designing a new version, but the latest update was four months ago, when they said they are ‘getting close’. There been nothing since then. It’s been several years already so when it will actually show up is anybody’s guess.
I’m hoping mine does not fail as none of the alternatives are quite as good.
The uptronics LNA has lower gain than the rtlsdr one so you might want to adjust your receiver gain to compensate.
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I had to up the Airspy gain from 16 to 20 to get the levels similar.
It is unfortunate because I had tested both LNAs before settling on the RTL-SDR for the Airspy and the RTL-SDR performed a little better.
After the gain change
Running on a noname SPF5189Z (possibly not that but works well enough … ).
Plus an an external light blue FA filter i had from before i ever used the rtl-sdr triple filtered LNA.
And a SAW filter after the LNA.
But i’m terrain limited to 200 nmi pretty much so it’s not really critical for me.
If rtl-sdr blog comes out with a new LNA for ADS-B i might switch 
When I started doing this I initially used a satellite TV LNA and a cable TV diplexer as a high pass filter. It worked pretty well, and I expect with a decent outdoor antenna it would get within 90% of my current setup.
Just for other people reading it, please mention that this is the broken LNA vs working LNA.
Not one of the LNAs against the other.
Same was my case.
The photo below is from year 2013 showing my first setup. It comprised of DIY 1/2 (1/4 + 1/4) wavelength Dipole antenna (installed indoor near a large window), Satellite TV in line amplifier, DIY Bias-T, 50 feet TV coax (RG6), generic DVB-T (black) plugged into Windows PC located in another room
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In February this year I ordered following low-cost 1090 MHz Amplifier-Filter. I received it in march, but could not test it as I do not have a spare PSU to power it.
https://www.aliexpress.com/item/1005004987445918.html
1090MHz ADS-B Active SAW Filter & LNA 5V Power Supply
Price US $7.83
Shipping: US $1.99
I now checked specs of this Filtered LNA on Aliexpress, and it said this filtered lna requires 0.1 A 5V USB-C, so I decided to use my phone’s charger to power it for testing.
The test setup is Generic DVB-T and its magmount whip antenna on a cookie tin. Below are results. 
Image 1 of 3: Setup with Filtered LNA connected
Image 2 of 3: Skyaware map WITHOUT Filtered LNA.
Image 3 of 3: Skyaware map WITH Filtered LNA.
LATER ADDITION (2024-08-19):
I conducted scan with and without Filtered LNA. No filtering at all 
SCAN1 - No Filtered LNA:
SCAN2: With Filtered LNA
I checked the SAW chip, but could not read what, if anything, was written there.
I have now ordered from another seller whose image clearly shows filter chip marking “1.09”. It is a bit costlier:
Price: US$8.04
Shipping: US$1.99
Total: US$10.03
https://www.aliexpress.com/item/1005004301129303.html
Click on Image to See Larger Size
UPDATE 2024-08-28
Today I received the Filtered-LNA mentioned above. It’s SAW Filter chip is NOT marked 1.09 (1.09 GHz = 1090 MHz) as listed at Aliexpress. It is marked 970 (970 MHz). Please see attached photos of the item I have received.
Click on Image to See Larger Size
Click Again to See Full Size
Aliexpress, Can’t trust the descriptions or the pictures. Something will get delivered weeks later, if what you get works at all consider yourself lucky. If it doesn’t work, good luck with support. At best you might get a partial refund.
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I contacted the seller. He told 970 is not frequency, but model number, and the SAW chip marked 970 is 1090 MHz filter.
I searched the web for Specifications, found Specs for Tai Saw 1090 Mhz filter, and found it shows 970 marked on it.
Page 2/7 of Specs
Page 5/7 of Specs
the bigger question, does this one work and filter as promised?
It does improve reception.
It has two components which contribute to improvement, the LNA & the Filter.
I cannot segregate how much part each component plays in improvement.
However for the price, I think it is a good bargain.
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Scan by Spektrum - Scan Range 24 MHz ~ 1800 MHz
Screenshot 1 of 2:
Antenna > Generic DVB-T (Black) > RPi Model 4
Gain = 49.6
Click on Screenshot to See Larger Size
Screenshot 2 of 2:
Antenna > LNA+Filter > Generic DVB-T (Black) > RPi Model 4
Gain = 33.0
Click on Screenshot to See Larger Size
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Performance
Screenshot 1 of 2:
Antenna > Generic DVB-T (Black) > RPi Model 4
Gain = 49.6
Click on Screenshot to See Larger Size
Screenshot 2 of 2:
Antenna > LNA+Filter > Generic DVB-T (Black) > RPi Model 4
Gain = 49.6
Click on Screenshot to See Larger Size
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On Screenshot 2 of 2 for performance (LNA + filter), shouldn’t the gain be 33.0 ?
To conduct the two scans, dump1090-fa on RPi was stopped to make the dongle available to scanning software “Spektrum”. During both scans (with & without Filtered LNA) the gain was set through the Spektrum.
After finishing scan, I stopped “Spektrum”, and rebooted Pi. This resulted in that dump1090-fa started and grabbed the dongle. As the dump1090-fa setting was ADAPTIVE_DYNAMIC_RANGE=yes, the gain was automatically set to 49.6 by dump1090-fa for both cases (with & without Filtered LNA).
I did not try to manually drop the gain to 33 in case of Filtered LNA.
I have now repeated the performance test, this time making ADAPTIVE_DYNAMIC_RANGE=no and manually setting RECEIVER_GAIN to 49.6 (in case of without Filtered LNA) and 33 (in case of with filtered LNA). Followings are the results:
.
Screenshot 1 of 2:
Antenna > Generic DVB-T (Black) > RPi Model 4
Gain = 49.6
Total Aircraft: 36
ADS-B Message Rate: 195.8/sec
Click on Screenshot to See Larger Size
Click Again to See Full Size
Screenshot 2 of 2:
Antenna > LNA+Filter > Generic DVB-T (Black) > RPi Model 4
Gain = 33
Total Aircraft: 80
ADS-B Message Rate: 263.0/sec
Click on Screenshot to See Larger Size
Click Again to See Full Size
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Can i get to see the setup picture, Have you decresed the gain
Antenna > LNA+Filter > Generic DVB-T (Black) > RPi Model 4