SBS-1 LNA - Performance Increase now Dropped

[J546]

Hi All,

I wanted to run this by the forum members for any comments on what could be going on with my SBS perfromance when an LNA was introduced.

I have been using a Nooelec Lana - Ultra Low-Noise Amplifier (LNA)  on my SBS-1 and the results were fantastic. I increased my range by at least 100 miles in some cases. Recently, the coverage has plummeted, to almost 90-100nm with the LNA in-line. I have tested the cables and connections for faults, or anything else that may cause a signal loss and found nothing. I even purchased another LNA, and the results are just as poor. If I remove the LNA , the coverage improves to where it used to be before the LNA  (170-190nm). Very confused. Pictures below.

I'm not sure if the SBS1 was being overloaded by the LNA? But then why now, unless the LNA has damaged the SBS?

I'd be interested in any opinions

Thank you in advance

Antenna Only

https://imgur.com/a/lf9Pmwd

With LNA

https://imgur.com/a/lf9Pmwd
https://imgur.com/a/lf9Pmwd
https://imgur.com/a/lf9Pmwd

Now with LNA

https://imgur.com/v5eo5PS

[jonboy1081]

I have never used an SBS1 but can you adjust the gain on it?, you may be overloading it.

How are you powering the LNA?, are you using the same power supply when testing between the 2 LNA's?, the power supply could be faulty.

[Anmer]

I was asked this question via a number of earlier PMs.  To avoid going over the same ground, here is a selection of my replies:


I've used a powered masthead preamp with an SBS and it marginally improved the range.  But never adding 100 miles!  Whereabouts are you located?

You can check your potential line of sight range using http://www.heywhatsthat.com.  There's an option to add an "Up in the Air" plot, entering altitude values.  Might be worth checking to see what your theoretical range should be?

I've no experience of the Noolec LNA.  Do you have a link to the specific device?

One thought is the LNA connected in the right direction?


Did you try Heywhatsthat?

The SBS is still working as before but range now decreases with the LNA in place.  That points to the LNA.  How are you powering the LNA and does the power go both ways?

My Bias-T blocks the power going to the receiver.

The link shows that the power may need blocking:

NOTE: Some SDRs will require a DC block between the LNA and SDR if utilizing the external power options. For more information review the product page or datasheet: https://www.nooelec.com/datasheets/100812


As I mentioned earlier, in my experience an amplifier adds marginal gain.  Heywhatsthat will show what your line of sight range is and that's typically what you can expect.  If you got more than that when the LNA was first used, it was possibly weather related gain.

[rikgale]

As an additional.

Have you had any new mobile phone masts or other transmission devices put up near you recently? Some mobile phone bands operate near 1090MHz and the LNA you stated in your post appears to be a wideband amp - "Wideband 20MHz-4000MHz" so you may just be 'throwing' too much at the SBS-1 for it to 'hear' the more distance, weaker 1090 signal.

If you have had new mobile mast try a 1090 filter.

Try a different power supply first as this will be the cheaper option to fix. If no joy try a filter.

[J546]

Thanks for the tip. I have not seen anything new in the area, it's be pretty static. I've used 3 different power sources, all 5v 1A on both LNAs.  The drop off has been so dramatic it does not make any sense.

[J546]

Update: Happy to report that the flightaware filter cleared up my issue. coverage has returned to normal. Targets now back to 200-210nm There must been a new  mobile source around here that caused the drop.

[Anmer]

Thanks for updating your post with the filter fix.  Others may find themselves with similar issues and it's good to know what works.