FlightAware Discussions

140' Tower / Which LNA to use

Hello, I have previously inquired about my build out. I have a 140’ tower on my property and want to install high quality equipment. So far I’m planning on using the DPD antenna https://dpdproductions.com/products/ads-b-vertical-outdoor-base-antenna

My question that is not clear to me yet is the LNA. Planning on using RG6 200’ total from top of tower to inside the base station hut. Looks like KU LNA 1090-2 TM is recommended. Well that being said their site is in German and I cant really understand pricing and shipping. Is there another high quality option from the US. Also placement of the LNA questions, Should it be inside the Base Station Hut or up on the tower close to the antenna. Most of the LNA’s I see on the market are not outdoor rated.

https://shop.kuhne-electronic.com/kuhne/en/shop/low-noise-amplifiers/KU+LNA+10902+A+TM++Selective+Low+Noise+Amplifier/?card=1813

They have an English language page, see above.

Other LNAs you’d need to put into an enclosure.

RG6 is no good at 1090 Mhz, the losses will be significant (i’m sure you can look it up).
So if you would use that, the LNA would need to go close to the antenna to avoid losing signal.

With LMR400 or comparable it would be feasible to put the LNA at the base or even the hut.

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Personally I think it would be a waste not to put the LNA up the mast.
200’ LMR400 will cost around 9dB.

How do you get the antenna to the top? Do you climb it or can you lower it?

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Didn’t calculate it, 9 dB is quite some loss indeed without an LNA boosting the signal before the coax run.

Still feasible but you’ll probably have a hard time receiving stuff further than 230 nmi or so?
Anyhow that’s just a wild guess, if you want maximum range the LNA needs to go near the antenna.

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I have hired a climber to get to the top. The antenna is not currently up. This is why in inquiring so I get it right the first time.

I cannot find a LMR to place at the top. At least one located in the US.

DanielTabellion.com
(330) 268-3613

https://usacoax.com/custom/mpd-400-ultraflex-super-flexible-ultra-flex-coax-cable.html

You mean you can’t find an LNA to place at the top?
If you’re not going for the Kuhne which i’m sure ships to the US, i’d recommend making a small enclosure at the base of the tower to have “only 140 ft” of coax.
Or you could even get a small enclosure for another LNA to place the enclosure near the top of the tower.

And if you’re not putting the LNA at the top, don’t even think about using RG6, the signal loss will just be too much. Might even be too much with an LNA.

Anyhow good luck.

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Others advice is better than mine for LNA, but I would certainly say you should try to mount it at the top of the tower if feasible.

For this DPD antenna, I just tested it for a few days myself on my backup/test station. It’s pretty good for range, especially improved distant aircraft message rate over the FA antenna. My results were mixed for total aircraft count though. I suspect nothing important, just fewer ground station TIS-B/ADS-R planes based on what I could see in Graphs1090 and watching live in tar1090.

My mistake though, I didn’t tape the connection to the cable during my test. And the N-type connector on the cable completely filled with water during rain on the third day. Performance obviously decreased. So… be sure to tape it tight with self-sealing tape if you get this antenna. This is obvious to most, and critical. Also, I zip tied to the mast the short cable coming out of the base of this antenna to keep it from flopping in the wind. It’s fairly low grade cable and kinked and maybe damaged itself a bit around the zip tie. So use multiple zip ties or tape might be more gentle on this weak part! Tell your climber not to pull on that tail coming out of the antenna at all.