Thanks for explanation.
Strong, not bad 
Mostly i’d like to see the signal graph with and without the LNA …
Just let it run 20 min with the LNA and copy the 1 hour signal graph.
You are right, strong signals indeed. My bad 
Here are the graphs after I after I interposed the LNA and the dc blocker between antenna and SDR at time
17:20.
Is there a difference between LNA with of without power?
LNA without power should still let through some of the strongest signals.
A couple of months ago, I got a new LNA that started to oscillate the moment I applied power and they replaced it under warranty.
I will check it next.
The noise is at 0 dB … LNA on the FA pro is completely overloaded.
I believe i mentioned to set the gain to 25 before doing any of this?
After I installed the Automatic gain optimization for readsb and dump1090 fa yesterday evening and just now I reduced the gain manually to 25. The graphs without LNA are now looking like this:
I can carry out the tests with LNA on friday at the earliest.
Without the LNA added you’ll need probably a gain of 40.
Then with the LNA, take it down to 20 for good measure to see if we get anything useful with the LNA and low gain.
Your picture of the graphs with LNA showed the noise level at -0 dBFS, so very loud, only noise.
That means either the LNA is defective and only producing noise or much more likely due to the LNA increasing signal as well as interference, the internal LNA in the FA pro+ stick is overloaded completely and you can’t receive anything.
Unfiltered LNAs are often gonna cause only issues and won’t improve reception.
Especially if your SDR already has a builtin extra LNA.
Still worth it to test with LNA with lower gain, see if that changes anything.
Which is more recommendable? The automatic gain optimization or the manual setting of the gain?
My script only changes a step a day … long term that’s just fine, but testing stuff … why wait.
I myself know what i’m doing so i’d never use the automatic.
The considerations aren’t that complicated, there is actually a link on what to manually do.
But if you don’t have any signals, then my auto-adjust won’t even work.
Here are the new graphics, first without LNA, then with unpowered LNA (gain set to 20) and then with powered LNA (gain back to 20). Obviously, signals still go through with the unpowered LNA, but nothing happens as soon as you connect the voltage to the LNA. I am at a loss.
As soon I removed the LNA and put the gain back to 40 all works properly again.
I suspect your LNA is malfunctioning. I’d contact the supplier and ask for a replacement 
It seems to completly saturate your reciever when powered on.
I’m 99.9% certain that you are suffering from overloading of either the first stage device in your Prostick Plus or your wideband LNA itself.
This is exactly what I would expect to happen if you use a wideband amplifier. You either need to change the amplifier for a filtered one or put a filter between the antenna and the wideband LNA.
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That or amplified interference overloading the LNA in the prostick+.
I suppose he could run the LNA without antenna connected and check what the graphs show to distinguish a bad LNA and interference causing overload.
I had a similar problem, signal drop mostly like shown on your graphs. It was a malfunction on the bias area, an foulty connexion. If you have an variable power supply try to increase the voltage, starting with zero Volts and see what happens when the lna is starting - I assume will happen at arround 3 Volts.
P.S. Assuming that you have an external bias tee device. One more stupid question: are the contacting parts clean? Can you try it with a different antenna? Just to make sure thats the LNA is working?
Sounds as though it could be a duff LNA.
Today I tested with two different LNAs and without a connected antenna. The 1st LNA is a Noalec and the 2nd is an inexpensive Chinese one. Here are the graphs:
Yeah the noise level is low.
Pretty sure it’s just interference and you’d need extra filtering when running an extra LNA.
Only way to really be sure is to add a filter …
But if the LNA was broken like some here suggested i’d expect the result to be the same with and without antenna.
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