RTL-SDR vs FA Blue vs FA Orange

Hi all

I’m looking at a replacement dongle for one of my feeders, as I want to repurpose my current RTL-SDR for something else. Now the question I have is, do I just buy another RTL one or get the FA Blue or Orange (I do have the RTL-SDR 1090 lna/filter that I would like to keep or I do have a uputronics 1090 LNA I could also use if BiasT will be a problem)

What would you suggest, I can’t really afford the likes of an Airspy ect, though I do think I’m at my limit on A/C & Range due to terrain but if one dongle is better than the other 2 and may give me a little more, then feel free to chip in with advise :grin:

It depends a lot on budget and interest.
If you choose a receiver with built-in filter, you can never repurpose it for something else - your call.
Then it comes to how you plan to put it together. Without a doubt, a receiver with built-in filter and amp is the easiest performance improvement you can make.
The next step up is something like the RTL-SDR V3 with the matching filter/lna. That said, much of the benefit is lost if the lna is mounted next to the receiver (I need an 8dB attenuator between mine to get the best out of it).

If as you say, you are terrain limited, your rate of diminishing returns is very steep.

Why do you need an 8-dB attenuator? Is there some kind of interaction between the LNA and RTL-SDR dongle, that you are trying to isolate one from the other? I have the LNA directly connected in front of the dongle, not even a piece of coax between the two, just an sma-sma adapter. Seems to work fine.

The RTL-SDR 1090lna is fairly high gain. This is great as it’s intended to be mounted at the mast-head.
When setup this way, the loss in the feeder becomes (almost) irrelevant.
By trial and error, I found I got the best performance by reducing the lna’s output.
If I’d done it properly and mounted the lna at the antenna, a lower/no attenuator would be appropriate.

I had a set of attenuators on hand, so it started as an interesting experiment.

With that 8-dB attenuator you can’t use the bias-T in the RTL-SDR dongle to power the LNA. Do you have a separate external bias-T ?

The SMA attenuators I use are DC Pass-through, so there is no problem.

It’s a good point as not all do.

I didn’t know there were DC pass thru attenuators.
Looking at the schematic for these attenuators they just show a short from input to output to pass DC. I would have thought there would be an inductor to pass DC, and stop AC (high frequency). Why doesn’t AC just go thru the short?

Well the replacement dongle will just be for ADSB nothing else.

I’ve got a number of dongles in use, (Radarbox, RTL-SDR, Flightaware Prostick Plus (Blue)), I get the best results from the Flightaware Prostick Plus.
Can’t comment on the Flightaware Orange stick since I don’t have one to compare to the others.

Do you use the prostick with an extra filter or as is?

DC pass or blocking is a characteristic you can select when ordering.

A traditional resistive attenuator cct typically look like one of these

An attenuator built with a high-pass filter will block DC (due to the series capacitor typically used).

I use it with the FA blue barrel filter for 1090Mhz.
On average it catches 200-300 aircraft more the the RTL-SDR setup, both are located next to eachother

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So is the filter in the stick not that good if people use the barrel one with it?

I think is has added value but the filter in the stick is located after the builtin LNA. So you amplify the noise as well.
By adding the barrel filter in front you eliminate that noise. It’s all depending on your environment, I live in a location with some strong mobile phone cell towers nearby in an urban environment.


Ahh OK, I have a spare RB 1090 filter I could use as it would be pointless in going antenna->LNA->filter->prostick

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Do you run your RTL-SDR bare-foot or with an LNA?
I found the performance of mine to be ‘uninspiring’ on its own.

I have neither.
I do have a few AirNav RadarBox FlightStick which are an approximant match for the Prostick Plus.

I don’t use an LNA with the RTL-SDR so it’s running barefoot indeed.

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Yeah, it’s a tradeoff – filter first or amplify first. Filter first increases noise figure. Amplify first has possibility of overload from strong out of band interference.


For a single pi node, why add any more un-necessary connections? I have a blue pro stick dongle (embedded filter) direct usb to pi and a short run of coax outside to my antenna about 30 feet agl.

Every component and connection (ps there are 2 connex for every 1 component) introduces a potential fault or failure. I like the engineering idea about keeping it simple (KISS).

But, I’m not an engineer.

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Well I ended up going for the prostick plus from pi hut as it was £12 cheaper than amazon. Its due for delivery tomorrow, so once its here I will swap out the RTL-SDR v3 and RTL LNA from my home feeder, with the prostick plus and RB filter and run it till next Sat and compare the results from next week against last week. I will prob also run the same week test on my 2nd site and see that result. I’m only changing it so I can repurpose the RTL unit.

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