Hello everyone, I am new to this,
Require help to run an coax cable for 50 Meters.
I have LMR400 Cable for 50 Meters, i want to install it and run though it, my equipment, Flighfeeder Orange, adsb anteena which has been provided by Flighaware. I was doing an experminet for example presently i am running an setup with 13 meter lmr400 cable and my signal srenght is good and iam receiving good flights. when i put one end of lmr400, 50 meter cable to anteena and other end to receiver i am droping much signal and flights, so i have seen many post regarding LNA installation, bought two type of lna and installed it and run a 5v througt it and i am not getting much signal and no success on it.
Request everyone to please guide me for my setup to install 50 meter cable.
According to the data sheet for LMR400 coax, at 1090 MHz it has 4 dB loss per 100 feet and it has a resistive loss of about 3 ohms (center conductor plus shield) per 1000 feet. So for 50 meters (164 feet) you should have 1.64 x 4 dB = 6.6 dB loss, and .164 x 3 = 0.492 ohms resistive loss. Add in connector losses and you get 7 dB loss and 0.5 ohms loss.
You didn’t say what gain the LNA has but typically it might be 25 dB. Also the current drain from the LNA might be 150 ma. If you have 25 dB gain followed by 7 dB loss, noise figure of the LNA won’t be increased much. Also 0.5 x .15 = .075 volts drop. That shouldn’t be a problem. So it should work.
How is the voltage being applied to the coax: from an RTL-SDR dongle bias-t or a separate bias-t ? Are you sure the bias-t is on ? Can you measure the voltage actually getting to the LNA? Sometimes it’s the simple things that go wrong.
Thank;you so much for the reply, as you mention everyting is correct as per calculation, total losses of 7dB, regarding bias-t, i have used separate 5v to power up and even i have checked that voltatge is being properly suppied, everyting looks good as per my check, Could you tell me the fresh installation procedure i will fallow as per you knowledge and do an installation and let you know what result i got it.
Plesase tell me one thing does LNA is to install at antenna end or Receiver end, which one would be better
This are the LNA which iam using, Please suggest me which LNA would be best.
You definitely want to install the LNA at the antenna. The 50 meter coax should go from the output side of the LNA to your receiver. The bias-t would be at the receiver end of the coax
I can’t tell from the LNA picture for sure, but it doesn’t look like that LNA can be powered from a bias-t. It can only be powered locally.
If an LNA can be powered from a bias-t, it accepts power on the output side coax connector of the LNA. An LNA like the Nooelec Lana can accept power from a bias-t.
If the LNA can’t be powered from a bias-t (like the one you seem to have), then you need to provide power locally at the LNA. Of course then you don’t need a bias-t.
Yes, true
This LNA is wide-band (20MHz-4000MHz) and it does NOT have a built-in filter. An external filter like Flightaware 1090 MHz filter will be required between Antenna and LNA. Alternatively an Aplifier with built-in 1090 MHz filter like Uptronics, or Airspy, or RTL-SDR Triple-filtered (Currently out of stock) will be required.
https://v3.airspy.us/product/upu-fp1090s/
https://store.uputronics.com/products/uputronics-filtered-preamps
The required location of LNA is CLOSE to Antenna i.e.between Antenna and the start of 50 meter long coax.
These two Amplifiers are wide-band (0.1 MHz to 2000 MHz) amplifiers, and does not seem to have a built-in 1090 MHz Filter. Will require an external filter
Thanks everyone for the suggestions, the above two LNA, why this LNAs are not performing as i power up external 5v supply, after provding supply then also im not getting proper dB gain, any suggestions, if any one LNA pls upload any pics for guidance.
I have this external filter, i thing will work for my project.
Any Diffrence between this two LNAs compare to Nooelec LANA-Ultra Low-Noise Amplifier(LNA)
That filter will work. The setup would be:
Antenna → filter → LNA → 50 m coax → SDR dongle. The only question is: do you feed power directly to the LNA from a co-located power supply, or do you feed power over the 50 meter coax using a bias-t? It depends on the LNA capability and the SDR dongle capability. Not all LNAs can be powered using a bias-t. Not all SDR dongles have a bias-t.
Edit to add: I see from your post, you are using a co-located power supply. How do you know you aren’t getting proper gain from the LNA? What are you basing that on?
How do you know you aren`t getting proper gain form the LNA?
Before Putting anything together, my setup is Anteena-Coax LMR 400 - 8 METERS- Reiceiver. that it, i am getting more flight good range and good message rate.
After Putting Anteena-Coax LMR 400-8 METERS- LNA- Receiver- 80% of no flights, no range.
After Putting Anteena-Coax LMR 400-8 METERS- LNA- Filter - 90% of no flights, no range.
Everyting has been double check and LNA has been power up with 5v co-located power supply. and its powering up has been check by mulitmeter.
Use tool such as SDR# or SDR++ to diagnose the performance of your setup variations.
These tools will analyse and plot the signals (including noise). They are easy to use.
My setup is directly plug in to the receiver provided by flighaware, any how i have an spare sdr dongle, with that i can do an scan let you the results.
The filter wants to go between the Antenna and the LNA, not after the LNA.
There is a good chance the LNA is being overloaded by things such as FM Broadcast, TV, PMR radio etc. as it is a wideband LNA.
You can test each antenna & cable setup with the spare SDR.
I think the point everyone is missing is that this set up is being attached in front of a Flightfeeder Orange - thus the person has no ability to adjust the gain, and the LNA is overloading the device.
Ok as you said yes, my LNA is attached in front of a flighfeeder Orange, i have seen many setups who are using infront of the SDR.
Ok I will try this setup and let you know.
But that’s not correct, the FF orange has a user accessible setting for gain.
(or at least it did at some point, and if it doesn’t have any longer i’d expect dump1090-fa autogain to be active).
Guys Please give some suggestions, with filter and without filter and no LNA which one is better. Gain is set to Max
With FILTER
Without FILTER
Done this but off no use, dont know whats going on.
I have an heavy drop in signal, no flights 90%, provided proper power supply 5v.
A defective LNA will reduce the signal instead of amplifying it.
To check if LNA is working, remove both the filter and LNA and use setup shown below. If LNA is defective, performance without it will be much better than with it.
Antenna >> 50 meter LMR400 coax >> Flightfeeder