Eastern Passes of AO-91 Also Work, But…

There is an impression among our local LEO satellite operators that Eastern passes of AO-91 do not work well because the already weak batteries are used by intense LEO satellite activity in regions through which the satellite passes before reaching us on the Eastern side. On the contrary, during Western passes, the batteries are in better condition as the satellite reaches us from Indian Ocean region with hardly any LEO satellite operators. Even then I tried listening in on an Eastern pass of AO-91 at 8.52 am. As it was a daylight pass, I was sure that the solar panels would be active and better as the pass was a bit nearer VU land than other land masses to the East. Just as I expected, I could hear VU2MZT calling CQ for quite a long time and later VU2AAP joined and they had a successful contact. I could hear VU2MZT even when the satellite was to the North, almost perpendicular to the direction of fixed Moxon Yagi pointed to the East.

But, I could not reach him in spite of multiple calls, nor could I hear myself on the downlink of the satellite. My Moxon Yagi has only a VHF Moxon driven element. UHF elements are passively coupled to the VHF driven element without any physical connection. So uplink on UHF would not have been strong enough to reach AO-91. Both VU2MZT and VU2AAP had much better antenna setup than me and that is probably why I could not reach them even though I could hear both of them well on VHF, the downlink of AO-91.

Went back and checked SWR for my Moxon Yagi once again using my cross needle SWR meter. It was nearly 1.7:1 on the nominal uplink frequency of AO-91 of 435.250 MHz, another potential reason why my signals could not reach the satellite.

On 145.960 MHz, the nominal downlink frequency of AO-91, the SWR was better at 1.5:1, one more reason why RX was presumably better than TX for U/V satellites with my setup. I have always found working U/V satellites quite challenging compared to V/U satellites.

Here is the audio recording of the pass after editing out most of the hissing noise of the open squelch when the satellite signals were not being received.

So finally, I have to improve my TX setup for working U/V satellites, though I have been able to have occasional contacts on U/V satellites in the past.