Low signal?

    • New


    Hi all,


    I am trying to get my first QO100 station working.


    I attach above pictures. I can hear the CW beacon just, but almost no SSB activity.

    I can point the dish using the very faint signal, I am happy it is in the right direction.

    I can also do the same for skew.

    I replaced the 75 ohm coax with some M&P coax which helped a little.

    I replaced the coax link from the Pluto plus to the power injector and also the output one also.

    SDR software will beacon track ok, the two lines are quite faint however.

    I appreciate the dish is quite small - I did try the slightly larger one, but the improvement was marginal at best.

    Any help gratefully received.

    • New

    Thankyou - yes I used the batc one. I am happy the direction is ok. I can move the dish angle and lnb skew to optimise, but still have very low signal....


    It is the very low signal that I would like some help with, Unfortunately I having nothing to compare with.

    • New

    Is it easy to remove the POTY and move the LNB to the focal point of the dish and try that? I am not very trusting of those plastic cones on offset dishes. In fact I think prime focus are a better bet for the satellite myself, you don't get rain down the POTY and you don't need to mess with the cone things :) The dish is probably marginal in size too...1.2 meter is a nice compromise.

    • New

    Thankyou for the replies.


    Yes I can remove the POTY - I will give that a try over the weekend.


    It is fed with 12v. I turned the LNB to calculated -19 degrees and that is where the signal is strongest.

    I didn't look for the DATV transponder, but can do that at the weekend.


    1.2m would be nice- not sure I have space for it.....

    • New

    Hallo M0MDS (name?),

    there is something basicly wrong with your receiver.
    What is the current consumption of the LNB? There must be much more signal even if the polarisation is false. If you switch on LNBs supply, the noise floor in the SDR Console gets up. Don't care about the skew angle, this is a further step. All the settings for the Console are correct?
    Did you ever try to receive terrestic signales with the Pluto, VHF-, UHF Relays for example.

    73

    Andreas

    • New

    It's hard to see, but the tube of your POTY does not look central in the circumferential mount. Is it? If not you could carefully try wiggling it into a different position and see if the signal improves. These things are pretty critical to get a decent signal.


    I am sure it does, but have to ask just in case ... :) The POTY tube does go through the red cover on the LNB and butt up against the alloy of the LNB's body itself, doesn't it?


    Can you test everything bar the dish and LNB on someone else's known working set up, locally?

    Chris, 2E0ILY in North Shropshire, England.

    Edited once, last by 2E0ILY ().

    • New

    Thanks Everyone,


    To answer the questions.

    1. Yes the POTY tube is pushed all the way into the LNB. I have another Bullseye LNB arrived this morning, So can test this weekend without POTY.

    1b. I made a slight offset mount for the POTY as it needed to clear the arm. Does a few mm make a big difference?

    2. Noise floor definately changes if you power off the 12v to LNB, so it looks like it is working.

    3. I can pick up FM Radio and local 70cm repeater loudly with a small piece of wire in the antenna port.

    4. It would be great if I could try someone elses setup but I don't know anyone local with a QO100 station.

    5. I read you can change the jumper settings on the Pluto Plus to use different firmware from the Adalm Pluto. Will try that also.

    6. It may be possible to borrow a Adalm Pluto for comparative test also.


    I hope to have a 1,2m dish on loan over the weekend, so will be able to try that also.


    Mike M0MDS

    • New

    Saturday 30th Nov.

    Thankyou for all the great comments.


    So this morning I removed the POTY and used a new Bullseye LNB on the smaller (sky) dish.


    I was able to just hear GB3RS (538) in a qso giving a IO91PX grid ref.

    Also heard F6?BH on ssb and IK2GRA on CW (579).


    Although very faint - this is a good step forward.

    The s/n ratio is still very poor, but at least it sort of works.


    The SG pre-amp and amplifier arrived this morning also, so might give that a try later.



    Mike M0MDS

    • New

    It'll be interesting to see what a different dish brings to the table. I put a friend's brand new "high quality" 1.2 meter dish on the surface table and it was so far away from being flat around its circumference as to being a joke.


    If you have access to something of sufficient area that you know is flat it's worth checking prime focus dishes as apparently not many are very flat, (even before they've been through the courier system's free of charge crash testing schemes).