Posts by pe1chl

    Why all the others need dishes ?

    I did not try this yet (will try later today) but I was kind of expecting it because of the very strong signal via the dish.

    However, I guess for optimal receive performance you need a small dish, maybe 30cm, at least.

    Also remember that the usage is now quite low. When the entire transponder is populated like a HF band the power available to a single QSO decreases.

    (even worse when the transponder goes into AGC due to that)

    Easiest would be to set AZ and EL to optimally receive Astra2, then tune to the amateur transponder frequency and turn the dish slowly towards the west until you see the stations on the transponder (or at least the beacons) and optimize on those. The EL probably doesn't have to change for this small dish.

    It is easy to find if your dish is optimally aligned once the bolts have been tightened by gently forcing the edges east-west and up-down and see if the signal improves when moved from the neutral position. If so, loosen the bolts and re-align.

    When you have no access to the receive signal strength when you are handling the dish it is all a lot more difficult, so at least try to arrange that. 2nd best would be to have someone watching the receiver and issuing directions by shouting or using some handheld radios/phones, but this is a lot trickier than watching the signal strength while adjusting it yourself.

    naturally every situation must be analyzed in the specific conditions. In any case, these two economic instruments allow you to make a very accurate aim in a few minutes. The analog instrument is very sensitive while the Sat Finder tells me if I'm aiming for the right satellite. The best solution compared to professional tools.

    Yes the analog indications are the best. In the old days when SAT TV was still analogue FM it was so easy to point to the satellite, now with those digital receivers that show a meaningless "quality" and "AGC" value that always lags by a few seconds it is much more difficult.

    However, the point is that you in Italy are lucky because you can receive the primary missions of those satellites, but in Northern Europe that is not possible or not so easy (there are a couple of BADR transponders that cover more to the North).

    And for someone in say Brazil or Thailand even that is not possible.

    So the location of the station really is important. In worst case only pointing to the amateur signals is possible. However, that is now possible because the beacons are on. Before Feb 14, one had to use other methods.

    Ah, an FT-790R :-)

    I have one of those (and an FT-290R) in the "junkbox". Used it on OSCAR-10 and -13 (with home-made amp). There even exists a video (very bad quality) of our fieldday in 1985 where it was used :-)

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    Now I am using an FT-817ND as part of the station for QO-100.

    Update: first uplink test made with 2W from LZ5HP transverter (not verified; according to others it could be 1W as well) via 10m of cable (-2.3dB) into SHF-1340 yagi (40el) which still needs optimization of pointing.

    Result is: QSO possible but weaker than average station, should find some 5-6dB I think.

    When visiting, the parent site of the PA3FWM WebSDR receivers, the BATC WebSDR now appears at the top of the list, which is sorted to average number of listening stations.

    Every time I have looked there, PA3FWM's own WebSDR (which uses different software and covers the entire HF bands) has always appeared at position #1. Now it is #2...

    So it looks like P4A is quite popular :-)

    For reception of BADR 4 BSS Beam in northern europe a big dish (>2m) is necessary.

    Even in south east DL 120cm is recommended - with my 85cm I am at the edge - some weaker transponders are "unstable" at "bad weather".

    73 de Johannes

    It really depends on the actual location which he does not seem to want to reveal (hmmm...)

    Here in JO22MC (center of Netherlands) the transponder 15 (11996) is received with about 7.5 dB S/N on a 80cm dish.

    But of course in Scandinavia it will be much weaker.

    Depending on the actual location there are different satellites that could be used as guidelines for first pointing efforts, e.g. Astra2 at 28.2 or Astra3 at 23.5 but without any more detailed location info it is difficult to recommend anything.

    CW is fine for an old cw-enthusiast.

    But a steady CW-Carrier for around 5 - 10 seconds for measuring between the rounds would be fine.

    Well, I meant morsecode sent as FSK so still easily receivable for a CW enthousiast (with proper filtering and tuning) but within a somewhat larger passband (SSB) it would have constant amplitude.

    But indeed, a ling tone between the text in the loop would be fine as well!

    Yes, according to the recommendation given before.

    Now that there are only a couple of stations active (or none at all) of course the power budget calculation that assumes 50 parallel QSOs is not really valid and required power could be lower.

    You should take back tx power especially for CW.

    I think the lower beacon would better transmit FSK instead of CW so it is easier to compare to the amplitude (same as terrestrial UHF/SHF beacons usually do)

    There is a picture on page 2 of this topic. Those splitters are readily available from satellite-TV equipment stores and webshops.

    But this is not at all critical. I made my own bias-tee from some junkbox parts.

    The LNB has such a high gain that anything you do to the IF signal (like lossy cable or splitters) really doesn't matter, you already need to turn down the gain of the RTL sticks by 20-30 dB to avoid overdriving them...

    Ok that is important because then you cannot use the transmitters of the primary mission of the satellite as guide when pointing the antenna.

    In the early days there were engineering beacons that you could use but they have switched over to the narrow beams that are only receivable in the arab region.

    Same for the DVB transmissions. Those cannot be received in Northern Europe with small dishes.

    So you need to tune to the amateur transponder frequency and use that for fine pointing.

    You are right, just calculating the AZ and EL and then pointing there is not going to work. It can be used as a first guess but then you need to just move around that position and optimize the signal.

    He has a 2.3m dish. Of course then you require less power than with a 60cm dish for which the 10 Watt was calculated (which most people immediately doubled due to past experience with pre-published link budgets).

    However it appears that there is less power required than estimated, at least when everyone behaves well.

    It could become worse when there are many simultaneous QSOs of course.

    It appears that the majority of stations receives with an SDR or at least has the capability to look at an SDR on the side, so I expect that once there is a good reference and understanding of the proper level the situation will be better than in the old days when everyone heard only their own signal and could not easily compare with others.

    (it also helps that the downlink signal is so strong that there is no need to make extra power to hear oneself due to local interference on receive)