Good morning, Andre!
Reading your story I set out this morning in my backyard trying to make a mode V/S QSO on AO-51 using my portable setup. I already tried receiving AO-51 mode S some time ago and that went very well but never tried uplinking.
The first pass this morning at 0805 UTC was not very good as the trajectory of the satellite was blocked several times by houses of neighbors and trees. I managed to copy myself once though. The second pass, 0945 UTC, was much better. I didn't hear many stations but managed my first V/S QSO with ON5SA :)
Congratulations! The uplink part for V/S is easy, as it is the same thing as V/U except there is no PL currently required. I had no worries I could do that, but needed to get the downlink and all those issues sorted out when I tried it for the first time.
I used a K5GNA downconverter with a homebrew hybrid quad antenna connected to a Icom IC-R20 all-mode receiver. The hybrid quad antenna with the downconverter were mounted on a tripod. Uplink was a FT817ND (5W) using VOX with a headset with mic. Uplink antenna was an hand-held Arrow.
I could use my FT-817ND in the same role, but I decided to stick with HTs as my TX and RX radios since I had already used them for more satellite work than the 817.
I think that it's better to mount the Arrow on the tripod and hold the K5GNA in my hand as it is much easier changing polarisation that way. Something for next time ;)
Or if the downconverter and its antenna were mounted on the Arrow, so it is a V/S antenna and then maybe the tripod. I saw pictures of someone who put an S-band downconverter on their Arrow antenna, and that would have been very helpful. Could I stand outside and hold the V/S Arrow for an entire pass while transmitting and keeping up with the receive Doppler? Not sure, but something to think about.
Also, my backyard is not ideal for mode V/S experiments as much of the lower elevation sky is blocked by plants/trees or buildings.
My home QTH has mountains about 2-3 miles (3-5km) to the south and southwest. Not very good for those directions, even for V/U. Outside my office near downtown Phoenix and at a park near my house, I can do better and work lower passes without many problems. My backyard is also not a great place for satellite experiments; the front yard is a little better except those mountains are still there.
I have other 2.4 GHz antennas, including some for WiFi stuff, that I might try. I've probably run out of time for much S-band experimentation for this week, but now that I've made some QSOs I will try for more the next time V/S returns to the AO-51 schedule. Or try to improve my L-band setup so I can make some L/S and L/U QSOs from a portable/temporary setup.
73!
Patrick WD9EWK/VA7EWK http://www.wd9ewk.net/