Most amps won’t pass anything (or very little) when powered off,so if your performance doesn’t drop dramatically, it’s working.
Of course what you’ll be hoping for is a dramatic increase that leaves no doubt it’s working!
here is my RTL-SDR 1090 LNA in a box. the two black things on the front are high air flow waterproof vents . Amphenol LTW. the box has been up for 2 years now in very high temps and driving rain with no issues
anything is ‘compatible’ with the right talent and a soldering gun.
But this stuns me too.
was eyeballing this and had a thought…
you could probably make a tiny solar station to power one of these.
Not too tiny - once you do a power budget and allow for a day or two with no sun, it works out bigger than you’d expect.
So today I had to do it; climb up the roof to install the LNA.
(I HATE going up the roof). But it was all for nothing; when I had connected everything up
(RPi → FA dongle → FA filter → bias tee (powered from the RPi GPIO pins) → flat coax - ‘normal’ Hirschmann coax → LNA → FA antenna) I got nothing. Literally.
PiAware was receiving nothing.
I checked every connection.
First I thought: voltage drop (5V will go down over such length) but a bias-tee with LNA is made for longer coax runs.
Now I think it’s probably the short piece of flat coax that’s causing problems; maybe there the 5V isn’t going through right.
I don’t know yet. But it was getting late so now the antenna (and LNA/bias tee) is inside behind a window so I can test everything out next week what’s causing the problem.
Bit disappointed; I was hoping for at least the same results, hopefully better but not worse! 
After all; I had to get up that &)()^ roof several times for this.
EDIT: also; 4 years of exposure to the weather does have its effects on the hardware.
EDIT #2: I found a empy spice box and the LNA fits perfectly inside.
Some hot glue around the adapter that sticks out and that should do the trick.
“Nothing” is really unusual, did you change the gain by chance?
I made the mistake after a reinstall. wanted to change gain from -10 to a lower value (42.1) but have forgotten to remove the “minus” sign, so i set up -42.1
Result was to see absolutely nothing on the map.
What’s the overall length of your setup between Antenna and Raspberry?
No. I’m using Automatic gain optimization script from wiedehopf but that only changes the gain once a night (if necessary).
One correction; the first time I turned the RPi on I was seeing maybe 5 aircraft. Then I did a reboot and since then nothing. I think there was maybe 1 aircraft but without location on the map.
There’s about 20cm of flat coax and then it’s around 10-12 meters (I don’t know exactly but something like that).
ok, it was just an idea
What is the usual traffic in your area?
This: https://nl.flightaware.com/adsb/stats/user/Iemand91
This was early this afternoon, just before I turned the RPi off to change the hardware.
Ok, then there’s definitvely something wrong. But let’s wait for the experts here.
You really want to put the FA filter between the LNA and the antenna. That way you reduce the unwanted, out of band, signals going into your LNA and stop them producing intermod products in, or overloading of, the LNA.
Beside that i was experimenting with such a flat cable as well. The cover promised me very good dB with minimum loss.
Reality was a loss of 40% once i closed the window where the cable was located.
I decided to put it into trash
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Did performance recover once you’d opened the window?
ie. was it an effect caused by the window, or was it destroyed when the window was closed?
Yes… that was the case. window open - works, window closed - decreased performance
I’ve identified that the frame of the window might contain some sort of metal which blocks obviously the system. So in reality it was not the cable itself or only.
We moved afterwards to a new flat, so i did not do any further investigation.
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Thanks.
I’ve used the ‘mostly flat’ type that have slim coax, but never the “very flat” foil type.
They worked fine on both VHF (AIS) and satellite downlink (~1GHz), so I’m interested why yours performed so badly.
If you had the foil type, metal in the frame is a likely cause.
Could I not skip the FA filter all together? The LNA filters unwanted frequencies too right?
I know the short piece of coax is not ideal but it has served me fine for 3+ years. Results with it can be seen in my profile. However; the outside white mantel of the cable starts to come off; some parts are now down to the metal conducter inside it. So I think the setup with LNA wasn’t working because of that. (Maybe a short or something?)
As for now; I haven’t tested other parts yet.
Saturday afternoon after the failed installation; I placed everything inside behind a windows since it was getting late and I didn’t want to loose my streak time. 
Setup is now RPi → FA-dongle → bias-tee → LNA → FA-antenna and it’s working fine.
The map isn’t wildly different or worse then the map I posted above in this post.
(So if I get everything working again on the roof WITH the LNA; I should get some pretty nice results I think)
As you people have said; if the LNA isn’t working or is broken; I shouldn’t get results in the first place. So the problem is likely the flat coax or the long Hirschmann coax (or maybe voltage drop?)
(I checked all the connections/connectors)
A bit weird, since both of them were working fine for 3+ years without the bias tee + LNA.
But testing may take a while since I’ve other things going around and they expect a heat wave this week; so I’m not planning to get up the roof since it’s going to be WAY to hot.
I used a better one, announced as shielded to avoid any damage. It was a bit thicker than the foil type.
Maybe it was simply my environment. I’ve read some other comments regarding “works fine on satellite but not for this single frequency”.
Anyways, my problem is solved by moving everything outside.
You’re using indoor grade coax with no UV stabilisation.
Water will have got inside and degraded it.
Time for a new cable.
Quite probably. However it really depends on your local RF environment.
Only way to really find out, is to try it and see.