DRO LNB for testing RX signal levels?

  • Hi there,

    Looking for potential projects while being stuck at home, I started investigating if there is a way to get QRV on QO100 from my home QTH, since antenna options are quite limited here. However, I do not want to start with larger investmsnts only to find out that it doesn't work.

    As a first step, I tried to point towards QO100 with a compass. I figured out that from my balcony, I should just about "see" it between the edge of the building and the roof of a neighouring house.

    Next week, I'l probably get a hold of a 72 cm dish as a start. In my cellar, I found 2 old LNBs which most probably have a DRO. I also have a RTL-SDR.

    The next step would be to check if I can receive any signals from QO100 preferrably with what I got at home, and start investing into more equipment once the Proof of Concept is done.

    Is this possible with a DRO LNB at all? I don't expect to be able to monitor QSOs with that setup, but at least see something that confirms that I don't waste my time and money when I get a proper LNB and other stuff to set up a proper RX path as a next step. Any hints on how to do this test and what kind of RX signal I could see or hear with my RTL-SDR?

    73 Jens, HB9EKO/DL9SBM

    • Official Post

    As a first step, I tried to point towards QO100 with a compass. I figured out that from my balcony, I should just about "see" it between the edge of the building and the roof of a neighouring house.

    Hallo Jens

    This is better than a compass: https://www.dishpointer.com/ . Choose "25.9E ES" and then your coordinates.

    Good luck, stay save & healthy

  • I suspect the noisyness and instability of the DRO would not help your efforts as I'd expect the signals to be "smeared out". I'd suggest to get a PLL LNB still. If you webshop, order two or three, so you can have an "accident" with one should you decide to GPS-lock your LNB in the future.

  • DB2OS

    Changed the title of the thread from “What kind of signal could I expect with a DRO LNB for testing RX signal levels?” to “DRO LNB for testing RX signal levels?”.
  • Hi guys,

    thank you very much for all the good hints. In the meantime, I downloaded a sat finder app on my phone and figured out that I can actually "see" the satellite. (Fingers crossed that reflections/multipath from the building don't mess up the RX path)

    I'll be getting a dish this week, so during the Easter weekend I'll use my DRO LNBs and try to figure out a landlord/XYL compatible position for the dish on the balcony. Once I can hear something other than noise, I'll give a feedback about my results in the forum and start online shopping.

    pe1hzg that was my first thought, too. However,after a web search for LNB models which have been successfully modified, I didn't find any in HB9 for less than the price of a modified LNB in the AMSAT-DL store. So I decided to first see what happens with what I've got, and then decide what hardware I need to order for the next steps.

    73 de Jens, HB9EKO/DL9SBM

  • Hallo Jens,

    the azimuth angle is sometimes critical due to magnetic influences in the immediate vicinity with a cellphone.

    At this time the weather is fine, try a check with the sun, also the shadow.

    You can calculate the correct time with https://www.sonnenverlauf.de when the sun has the same azimuth as AO-100.

    Observe the lluminated area where the dish is to be mounted.

    But only azimuth is this time correct, because the sun is meanwhile higher than QO-100, but your picture shows, there is no problem in elevation.

    73´s de Robert

  • Hi Guys,

    as promised, here is the result of my experiments: One of the 2 unknown LNBs received something. The best S/N I could get with the possible positioning of the dish was about 20dB. So as a proof of concept the DRO LNB was usable, although for following SSB QSO's, I had to be quick following the drift.....

    --> Goal achieved, Proof of Concept done without major investment.

    Thanks for all your support, now I have to get my equipment together step by step...

    73 Jens, HB9EKO