CT3 <> ON Tropo path on 144 MHz


On August 19th, 2021, I had the surprise to see “CT3KN” (IM12MT) on my screen in FT8 on 144 MHz at 10:56 UTC. Unfortunately, we couldn’t make a 2 ways QSO over that 2614 km path, 2-3 dB were missing to achieve it ! In 2011 and 2019, I already worked the Azores Islands (CU8) on 144 MHz in Tropo. Nevertheless, I never thought the path to CT3 (Madeira Island) would ever been possible. Indeed, if the sea propagation seems sometimes without “limits” (see the QSO’s on 144 MHz between D4 and EA8 and the Caribbean Islands), when there is land in between, that is another story. If on the path to the Azores the amount of land is very limited, on the path to Madeira, there is about 750 km of land to cross, with as many opportunities to have the tropo sea duct being interrupted.

Nevertheless, knowing that G stations as close to me as JO01/02 made their way to the Ricardo (CT3KN)’s log on August 18th evening, I called “CQ” from time to time with the antennas heading to the Azores on the 19th. And it paid ! Below a screenshot taken at my station :

CT3KN 144MHz Tropo SS WSJT 19082021

And here is the screen at Ricardo’ side at the same time :

ON4KHG at CT3KN side 19082021 reworked

Ricardo is using 80W and 2×9 elements antennas. I’m using 1,2 kW and 2×9 elements too. It makes a difference of more than 10 dB, which is somehow reflected in the reports seen. I saw Ricardo -19 dB at best and he saw me -11 at best. At -11 dB, my signal was barely audible in a reduced bandwidth. Hence, even in CW, a QSO would have been hard to achieve (at same RF power level both sides).

In the morning of August 19th, 2 EA1 stations lying on the path (both in IN73DM) have been worked too. EB1B has been worked at 07:27 UTC and EB1FNS at 09:42 UTC.

After analysis of the PSK Reporter data and my log, one can see :

  • 06:22 UTC : CT2HXM (IN60CR) sees my signal -12 dB. Thierry sees also G0MBL in JO01 at 07:23 UTC, nobody else around or in between. This can be MS or Tropo but I assume it was more MS than Tropo. See the map below.
  • 07:27 UTC : I make QSO with EB1B in IN73DM (-08 dB / -08 dB)
  • 09:42 UTC : I make QSO with EB1FNS in IN73DM (-08 dB / -01 dB)
  • 10:56 UTC : uncomplete QSO with CT3KN in IN12MT (2614 km)
  • 11:40 UTC EB1FNS sees my signal +15 dB. So, the duct seems to be stronger now, provided the antenna at the EB1FNS’ side was heading the same QTF (to me ?) at 09:42 too.

This is the complete path :

CT3KN Google Maps
CT2HXM, Thierry sees “local” stations and my signal at 06:22 UTC. G0MBL (JO01) is seen at 07:23 UTC. Surprisingly, no stations in between or around G0MBL and I. However, I checked PSK Reporter and there were not many F stations QRV on the path between 06:10 and 06:40 UTC (F0FWC and F0GFI, both in JO10. F4KKV in IN98. F4ELJ in IN78). At 07:27 UTC, about when CT2HXM sees G0MBL, I have worked EB1B but CT2HXM doesn’t see me then. So, the spot of 06:22 is probably MS, unless CT2HXM has turned his antenna between  07:23 and 07:27. Or, since I was in QSO with EB1B, not CQing, PSK reporter didn’t report my signal around 07:23-27 UTC at CT2HXM’ side ?

ON4KHG - CT2HXM 19082021

Looking at Hepbrun’s Tropo maps, the duct was clearly visible. It seems it peaked (for my location) between 09:00 and 12:00 UTC. The map below shows the Tropo forecast at 09:00 UTC on August 19th :

Hepburn Maps

This was a very thrilling experience, even though we couldn’t complete a 2 ways QSO !

In such nice tropo conditions, working Ricardo (CT3KN) should be easy in Meteor-Scatter (actually “Tropo-enhanced MS”). Hopefully, as from IM12MT, Ricardo is located on the North side of Madeira, while Funchal (the capital city), is located on the South side, obstructed to Europe by mountains. I’m looking forward to try in MS with Ricardo, if not trying again and succeeding in Tropo !


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