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Thread: SBS-3 losing sensitivity over time

  1. #1
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    Question SBS-3 losing sensitivity over time

    Hi all, I've tried Googling for this and searching the forum but can't find anything on this topic, so thought I'd post the question! Here goes...

    I've been using the SBS-3 since about 2016, so three years at least. I have an externally mounted co-linear type antenna, a mast-head pre-amp, a run of coax that runs to a bias-T and then into the SBS-3. I've had this installed since in 2016. When I initially installed this the SBS-3 could get contacts over 100 NM away, happy days. Now, with the same hardware and setup etc (nothing has changed, just time) I'm only able to see contacts around 50-60 NM away.

    A week or so ago I decided to buy an SDR and connect it to a Raspberry Pi, to feed FR24 (which is up and running). So I could run both FR24 and the SBS-3 side-by-side I built a home-made antenna, just to see if I could get it working. Dump1090 on the Raspberry Pi registers over 200 messages/second using the home made antenna, so happy days with that little set up, and I'm quite happy with what it can see.

    Now for the bit that's niggling at me!

    Out of curiosity, I took the external antenna connection that's normally connected to the SBS-3 (so the external antenna, pre-amp etc) and connected it into the SDR connected to the Raspberry Pi, Dump1090 shows over 600 messages a second and that gets contacts over 80NM miles away. If I take the connection and plug it back into the SBS-3, it can't see the contact at 80NM miles away, when it used to be able to see contacts at this distance when it was first installed.

    I know that the SBS-3 and the SDR are entirely different pieces of equipment, and no the antenna is NOT being shared between two devices simultaneously. I've checked all plugs, loose connections etc and everything is fine. SBS-3 is on the latest version I can see on the Kinetic website and Basestation is the latest version (I upgraded them when I got them and Kinetic haven't released a new version since - Kinetic seem to have gone quiet).

    The bit that's niggling at me is that it "seems" that the SBS-3 could see contacts over 100NM away when it was first installed, but seems like it's gone a bit "deaf" and lost sensitivity over time, and now can't see a contact 80NM away when another device can using the same antenna setup, and it used to be able to see to this range when it was first installed.

    My question is: has anyone else had a similar experience to this at all, with an SBS-3 losing sensitivity after a while, or going a bit deaf? If so, is there anything that can be done to rectify this or restore the original sensitivity?

    Thanks,
    Chromic

    P.S. Does anyone know what happened to Kinetic as they don't seem to be updating the firmware/software? The website still has a story from 2016 on the homepage...

  2. #2
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    Could be reading this wrong, but it looks like the -3 has software based radios similar to how RTL sdr's were born

    If that is the case, it could well be that some of the ICs/components have started to go sour. In the same way RTL sticks can go bad when theres not enough USB juice.

    More external from Kinetic support on woodair (I dont have a SBS and still use the maps etc) http://woodair.net/SBS/Article/Barebones46_Upgrades.htm
    Posts not to be taken as official support representation - Just a helpful uploader who tinkers

  3. #3
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    Hi, thanks for replying, I didn't know that ICs could "sour" over time through normal usage, thought they worked until they physically broke or became damaged, every day's a school day!

    I've had a look at the link and saw the note about power. That's one thing that has changed - the computer base unit. I've tried plugging the SBS into a 5v supply that can deliver at least 1amp, and also tried turning off the SDRs but the 1090mhz side is still the same unfortunately, so it seems the SBS-3 is the poorly one. Also tried connecting the power lead to 2 USB 3.0 ports and it's still the same. Just disappointing to think as I love the SBS-3

    Thanks,
    Chromic

  4. #4
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    Thinking about this overnight, is it possible for the pre-amplifier to be providing too strong a signal to the SBS-3, and this has lead to it going deaf? A bit like listening to music on your headphones too loudly, you can make out the music (i.e. the SBS-3 can make out the 1090mhz signals) but over time you damage your hearing and can't hear quieter sounds?

    Could it be that over years of the SBS-3 receiving an amplified signal it's damaged the ICs in some way?

    Thanks.

  5. #5
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    Hi all, just in case anyone stumbles across this thread in future...

    I decided to take the antenna and mast-head pre-amp down from the chimney and connect the SBS-3 directly into the antenna. Lo and behold, it's receiving signals quite well now, so it looks to have been an issue with the pre-amp all along (such a relief it's not the SBS!). Now the antenna is mounted on the side of the house, perhaps 10ft or so below where it would have been if it had stayed on the chimney, but to me it's worth doing that than having the pre-amp in line, and it won't be going back to the chimney (but that's another story).

    Personally I'm going to stay away from mast-head preamps in future, as it's another thing to go wrong and it's a pain to sort out unless you're able (and confident enough) to get to the chimney stack or want to pay someone to do the work lol!

    Thanks for reading.

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