RTL-SDR LNA Install

Got the NooElec with the bias tee in it and tested.

First thing I tested was the LNA mounted to base of the antenna. I got no flights(I adjusted the gain) with it in this configuration. I guess the long 25 foot cable was too much separation for the dongle to get the voltage to the LNA. So, I mounted it straight to the new dongle and it worked. While it didn’t work as well as the standard FA blue plus it did work.

When I get the bias tee from china I’ll test a few different bastardized configurations using the FA blue plus, LNA, bias tee and what ever else I see in the shop.

Thanks everyone for the help and lessons.

The 25 ft cable really shouldn’t be a problem.

Even if you didn’t have a bias-t at first, the LNA still seems to be defective.
If you hook the LNA dongle combo to the same SMA connector as the ProStick+, it should require some less gain but do at least as good.
At least that would be my expectation.

Sorry, I also meant to add that I had a replacement LNA as well. Got here yesterday.

Finally, first run

1 Like

Since you’re selling, how much for the butter cookies?

1 Like

@cantrepeat

Sorry, no more cookies left for sale, he ate all my cookies. :slightly_smiling_face:

Cookie_Monster

1 Like

What gain are you running? rtl-sdr LNA with the smartee, try a gain of 28.
Be sure to use the right method depending on your install: For Beginners - How to Set / Change Gain

Maybe the blue stick is just working better because it has less amplification.

1 Like

I’ve done the edit to allow the gain switching with the drop down menu in skyview. Nice mod for sure.

I tried gains from -10 down to 20.7 with the results weren’t that great. I couldn’t get much over 120nm and didn’t see many near range aircraft. I’m sure with more testing I could do better.

Right now I have the blue stick at 43.4 and getting a range 150+ NM while still seeing planes at 15nm at elevations of 500. I might be able to push gain up a bit but need to test.

Please check if the gain is actually changing:

sudo journalctl -u dump1090-fa

You should also see it in the graphs if they have those installed: GitHub - wiedehopf/graphs1090: Graphs for readsb / dump1090-fa / dump1090 (based on dump1090-tools by mutability)

I have installed graphs. Another great addition!

I do see the change in both the config file, the html display and the graphs themselves.

After short test run last night restored system back to normal as it was bad time to test due to very low traffic.

Reconnected today morning.

Before 12:20 pm
PCB antenna + FA light blue filter + FA orange stick

After 12:20pm
PCB antenna + RTL-SDR tripple filtered LNA + Bias-T + Generic DVB-T (black).

Gain in both setups = 45

.


dump1090-localhost-aircraft-6h

dump1090-localhost-signal-6h

I’d say you need to give the external LNA 10 gain less.
Should give a better comparison with more similar signal levels at the ADC.

Also comparing against the green or blue sticks is probably a closer race :slight_smile:

Could you show a signal graph comparison for the blue stick vs the LNA+nooelec stick?
Maybe at a gain of 40 for both, 1 hour each?

Also can you check if you get any undervoltage:

sudo dmesg --ctime | grep voltage

OK, reduced gain by 5 as first step. It is now at 40.

Will reduce by another 5 to 35 after an hour.

1 Like

Nothing found, so no under voltage warnings.

image

image

1 Like

this is a nice experiment. it will be interesting to see what gain and configuration (ie with or without lna) you finally choose

image

image

Well, I order a second antenna, an RTL-SDR.com powered dongle and another PI3b+ to further my testing.

Sadly, still, when ever I put the rtl-srd LNA inline I lose all tracking; even with the matching dongle I get nothing. I’ve tried 2 different LNAs with the same result. I’ve also tried the correct bias-T with a nooelec dongle. It doesn’t matter whether the LNA is at the antenna or at the dongle it just isn’t working for me.

that seems strange.

show a photo please of the setup.

Also describe which image you are using and what gain you tried.

With the rtl-sdr v3 you need to turn on the bias-t via software.