Why is that? I have not checked it yet, does it have better specs than other brand name filters, i.e. non eBay specials?
It says it’s a SAW filter.
With 950 MHz to 1150 MHz the light blue FA filter is just ridiculously wide.
It will help with strong FM or TV or other signals below 900 MHz.
But mobile pones will always be a problem.
A SAW filter has no choice but to be better in regards to bandwidth.
Agree, this is why I ordered the dark blue from the UK.
OK, I thought it was even better than other filters, SAW or otherwise.
After my experience with their SDR stick, I don’t think I’ll jump on their filter untill I read some reviews here. 
I have good experience with the Radarbox24’s Green Flightstick (1090), and have now ordered one more Green stick (1090), one Red stick (978) and one Blue Filter (1090), and one generic dongle “Micro”. Awaiting delivery.
Is a pic of the enclosure with the antenna. Its approximately 200mm from connector of the antenna to the point in the enclosure where the blue stick is mounted, maybe 150 from the Raspberry Pi. Should that be sufficiently distanced or does the antenna need to be further away from the enclosure?
I also remember that the 1mm differences in the length of the whip can be significant, but how sensitive is the performance on the length of the legs for the ground plane? This spider is built by soldering the legs to a copper washer, then mounting that on an F Type barrel connector with a washer at the top of it.
Just noticed that some Radarbox products are now available on Amazon Canada from Amazon.
Why is this?
The ADS-B signals are not limited by the receiving power, but by the Earth curvature and other obstacles. Raising the signal level is not always good, especially if you don’t adjust the gain, as you saw.
Again, why? Because you lose 1-2dB? You have to stop thinking in analog TV/radio reception terms.
My signal levels at the edge of my reception area are still strong, but they disappear suddenly after that range. Sometimes, at that point, they have -26dB, sometimes -17dB… it depends.
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On that point, this post from @obj explains where the rule of thumb for upper signal strength comes from – the “keep -3 dBFS or stronger messages to around or below 5%”.
I’m sure I read somewhere on here that messages with a strength of around -30 dBFS are merging into background noise (at least for the Pro Stick Plus), so that could be considered a lower bound when analysing results from gain changes. But I can’t find a reference for it now, and I’ve seen some people post results with numbers weaker than that and doing okay.
Assuming good open antenna with visibility all around, would it be correct take -30 dBFS as a rule of thumb lower bound for RSSI? As you say, the ‘loudness’ only matters in analogue applications, and in this application it only matters in the sense that too loud overloads the SDR front end. If the digital message can be heard weakly then it’s as good as being heard strongly from dump1090’s point of view.
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If the addition of cable is basically attenuating the signal, should/would it be reasonable to try an inline 3db attenuator?
So far, after building two independent systems with the same basic setup, they have the same behavior with the cable length, so my guess is I’m getting too much noise and things are getting overloaded.
Interestingly, with both setups I am able to get a significant improvement with just 18" of additional cable, which implies that just a short length of cable and a connector is enough to attenuate the overall system so that maybe the LNA isn’t overloading.
I was waiting to see if there was an feedback on the RadarBox blue filter before another case redesign 
Interesting, I wonder if your problem is caused by impedance mismatch between the antenna, cable and receiver causing standing waves in your feeder cable. 18” of extra cable introduces approximately 1.5 wavelengths at 1090 MHz. Does adding 6” extra cable (approximately 0.5 wavelengths) instead of the 18” give the same result? I know that some people will say that the difference between 75ohm cable and the 50 ohm ProStick causes insignificant loss but that is only really true if the antenna itself is also close to 50 or 75 ohms. If your antenna is grossly mismatched the system will be sensitive to the overall length of the feeder cable.
I’ll give that a try, thanks! (picture of the antenna is above, 8 leg spider, legs at 45degrees)
No, it should not give same result.
The impedance seen at receiver end of coax varies cyclically with length of coax. Please see diagram below
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Please also see this post, and next few posts:
https://discussions.flightaware.com/t/measuring-antenna-performance/19651/9
How did the RadarBox filter work out?
Receved it today morning, was busy, so did not even open the box. Will check tonight or tomorrow, and post findings.
From the graph you posted 0.5 and 1.5 wavelengths show the same result. The cycle repeats every 0.5 wavelengths.
Impedance Transformation By Coax
impedance seen by receiver varies cyclically with length of coax between antenna and receiver.
True.
The effect of coax on antenna impedance is nil when coax length is multiple of 0.5 wavelength. Therefore the receiver sees actual antenna impedance at coax lengths 0.5, 1.0, 1.5, 2.0, 2.5, 3.0 and so on. For in between lengths of coax, the receiver sees different impedance as shown in graph.
This is mentioned in my last post above. I am posting below the cut-out of relevant part.
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Very interesting! The cable that had good results was approx 54 inches (1371.6mm), and that is very, very close to 10 half wavelengths (actually 9.97). Taking out the 18 inch part and leaving only 36 inches is about 6.65 half wavelengths. Going to see about making a cable 6 half wavelengths long to see what happens.
DVB-T without Filter
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DVB-T + RB24 Filter
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At that low frequency a modest length of coaxial cable is a lumped element.