I am having some issues with my new Vinnant 7.5dbi antenna. I have been in touch with Stanislav and has been excellent throughout the troubleshooting but we may have hit a wall as to nailing down the issue. So i thought id see if anyone else has any ideas.
My setup is: Pi4 → Airspy R2 → Uputronics 1090 filter → LMr400 cable → antenna
I currently have an Alibaba 5.5dbi special which was cheap at the time. I have it mounted about ~5m over the top of the roof on a mast. No issues with this antenna for the past ~12 months.
I plug the vinnant 7.5dbi in to the same chain of equipment up on the mast and i get 0 messages and no planes.
If i take the vinnant antenna down on a long cable and stand off the ground around ~3m i can get some signal. Mostly of planes a very long way away (was a quiet time when i was testing). Once i got the signal i mount the antenna back up on the mast and nothing, it all goes to 0. I also walked around on the roof to move around (just in case of interference) and still 0 messages when above the roof.
Stanislav thinks there could be some interference however its weird that my cheap antenna works in the same spot and this one seems to be struggling.
Could it be that the 7.5dbi is to high a gain for my location? Should i be going back to a ~5.x dbi antenna?
Nothing changed in my setup or any environmentals changed when swapping between both antennas, so im a bit stuck as to what could be causing the 0 messages on the new antenna.
I have run a multi meter over the connections and there seems to be no issues.
Would anyone happen to have any thoughts or suggestions?
Well different antennas have different resonance frequencies besides the main frequency.
Thus … if the offending frequencies hits the resonance for one but not the other …
You could always get an FA barrel filter and put it before the uputronics.
That would decide if it’s interference.
But testing without the amplifier should also tell you if interference is the issue.
Assuming 5.5dBalibaba is a meaningless number, your 7.5dB antenna has probably added 6(+)dB to your system. The uptronics amp claims 16dB gain, so you should have a ‘lot’ of signal.
As above, start by removing the amp to see what happens.
If it starts working, replace the amp and try turning the airspy gain down (say 10dB) - see what happens.
Thanks for the suggestion here, i tried this as well and took out the uputronics filter, no difference in the signal. Ill attach some airspy graphs in a moment to this thread.
Great idea, i have one of these (blue one), ill go and test with that in front of the uputronics filter shortly and report back.
There is no signal when i plug it directly into the airspy device without the filters in front (this is when i have the antenna above the roof).
Great idea @wiedehopf, that did the trick. Putting the blue FA barrel filter in front of the uputronics amp lit up the antenna.
The current setup looks like this:
Pi4 → Airspy R2 → Uputronics 1090 → FA Blue barrel filter → LMR 400 → Antenna
This combination works and i can see the planes and messages almost back to where it was before.
After watching it for a few minutes (and switching between the older ~5.5dbi antenna) i can see the 5.5 seems to have about ~5-10% more messages than using the newer 7.5 vinnant.
Could this be due to moving up to a 7.5dbi from a 5.5dbi?
Would i be better putting in a 5-5.5dbi vinnant antenna and testing that out as well?
Thank you all once again for assisting here. Really appreciate it.
Why you call it Uputronics 1090 filter? It is in not only a filter. It is Uputronics 1090 filtered LNA.
LMR400 is a very low-loss cable. What is the total length of this cable?
May be Uptronics Filtered LNA is providing too much gain for a 7.5 dB antenna.
As the 5.5 dBAliexpress antenna may actually have much lower gain than 5.5 dB, it worked OK with the Uptronics Filtered LNA.
Try again with Uptronics removed but FA Blue filter in place, like this
Pi4 → Airspy R2 → FA Blue barrel filter → LMR 400 → Antenna
Apologies mate, that’s probably just me not explaining it 100% correctly. Thanks for clearing that up.
I reckon you could be right. Its weathered pretty bad over the past ~11 months or so. So wouldn’t surprise me if it was not a 5.5dbi from the start.
Thanks for the suggestion. I gave this a try, and from the hour or so i had it hooked up this way, it was running slightly less in the messages per second. Put the uputronics back into the mix and it seemed to be a little bit better. But ill need some more time to work out which combination works the best.
Will do mate, thank you. Ill run some tests this week with each antanna and see what the graphs produce.
Here is what i have tried so far:
Pi4 → Airspy R2 → Uputronics LNA → LMR 400 → Antenna = No planes were showing or messages
Pi4 → Airspy R2 → FA Blue barrel filter → LMR 400 → Antenna = Planes were now showing and messages per second was good
Pi4 → Airspy R2 → Uputronics LAN → FA Blue barrel filter → LMR 400 → Antenna = This seems to be the best combination so far. But as mentioned above ill run these different scenarios for the next few days and check the graphs to see which combination produces the best results.
Q. Since putting the FA Blue barrel filter inline, is this filter pretty good or are the other options out there that i should consider now i know this filter enabled the antenna to work?
In regard to the filter, I think is is very good at doing it’s job. Certainly for the price it costs.
There are cheap variants on Amazon and Aliexpress but I think the flightware filter is better in regard to performance and build quality.
I have the 7.5 dB VInnant antenna as well and use in in combination with the filter and the Flightaware Pro stick Plus. I had no issues in setting it up but the fliter has been there since day one of the reciver( I live in an urban environmetn with cell towers nearby). The 7.5 replaced a 5.5 dB version of the Vinnant antenna and it increased my numbers by 10 % or so. Most of these are farther away signals that are coming in now due to the increased sensitivity.
This one is also very good but the price is also 1,5 times more.
I don’t know if they ship to Australia btw. If your are interested you might want to look for a local supplier.
I am using exactly that configuration from time to time for testing purposes. Cable is 3 Meter.
Never had any issues, neither with autogain or manual.
Only if the Uputronics doesn’t get power, the Airspy is almost deaf.
Seem to be that as wiedehopf wrote the airspy is pretty fault tolerant within some boundaries.
And the performance is independent of the used antenna. (I do have a Jetvision 5dBi showing the same performance.
I suggest you place the LNA + Filter right after the antenna, then run the LMR400 to Airspy R2. The signals lost in the LMR400 cannot be recovered with any kind of amplification. Better amplify before any long runs of coax.
While you’re right that you get better linearity with amplification closer to the antenna than you do if it’s near the receiver, i just wanted to mention that 10 meters (34 feet) of LMR400 has just 1.7dB of attenuation at 1100MHz. The hassle of putting the LNA inside a waterproof housing that doesn’t also lead to premature failure from overheating and mounting it under the antenna may not be worth it.
That is why I keep all my electronics indoor, including the Antenna and Coax.
(Actually I am forced to do this as I live in an apartment with no open Balconies, and the Building Management does not allow anything installed on outer wall or roof, or an antenna protruding out of a window )
My whole equipment is outdoor since two years without special weather sealed treatment. It was so far a wooden box, covered by the roof of my flat.
Never had a single issue with it.
)